Measuring the Atlantic Slave Trade: A Rejoinder
Author(s): J. E. Inikori
Source: The Journal of African History, Vol. 17, No. 4 (1976), pp. 607-627
Published by: Cambridge University Press
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MEASURING
THE ATLANTIC
SLAVE TRADE
607
makes a further error in ignoring the additional restriction on slave cargoes
imposed from the end of 1799. The ratio thereafterworked out at a mere Io03
slaves per ton. Again, we reject Inikori'spossible rejoinderthat serious violation
of the 1799 Act was widespread, and would point out that his evidence about
the ship Vanguard (p. 220) really points more to the effectiveness of cargo
limitation.
Finally it may be of interest to suggest approximatefigures of slaves exported
in the period 175I-I807 on the basis of acceptanceof Inikori'sship and tonnage
totals but of Anstey's slaves-per-ship or per-ton ratios in the three disputed
decades 178I-1807. The result is a 57 year total of I,913,380 which is 18-4 per
cent higher than Curtin and 7-3 per cent higher than Anstey's original figure.
Pending any more detailed work of my own, using the invaluable Customs 17,
this is the approximationI am now inclined to accept.
MEASURING THE ATLANTIC SLAVE TRADE:
A REJOINDER BY J. E. INIKORI
This rejoinderdeals first, briefly, with ProfessorAnstey's comments, and then,
at greaterlength, with those of ProfessorCurtin.
I
I very much welcome the constructive comments on my article by Professor
Anstey, which have gone a long way to ease the task of reconcilingthe differences
between his estimateand mine. In the first place, we are now in agreementabout
the 5 per cent allowancefor non-slave carryingvessels or tonnage when dealing
with aggregatefiguresof vessels or tonnage annuallyclearedfrom Englandto the
Africancoast. On the basis of this agreementAnstey has acceptedthe numberor
tonnage of slave ships I compiled from Customs 17 for the period, I781-1807,
'pending any more detailed work' of his own, using Customs 17 (p. 607). This
has now narrowedthe differencesbetween our estimates to: (a) the number of
slave vessels and the averagenumber of slaves loaded per vessel for the period
175 -80; (b) the average number of slaves-per-vessel and/or slaves-per-ton
ratiosfor the period I78I-1807. These areasof disagreementnow accountfor the
differencebetween my original estimate and the new estimate which Anstey is
preparedto accept.
Since Anstey simply applied his estimatefor 1761-1807 to the decade I75 -60
without any fresh data, the discussion on the first part of our disagreementhas
to be restrictedto the period I76I-80. For this period, Anstey computed 2,415
slave vessels measuring 270,796 tons, which loaded a total of 559,543 slaves.1
The number of slave vessels is 8.I per cent less than the total of 2,627 vessels
cleared from England to the African coast in this period,2while the.tonnage is
7.8 per cent less. Both are therefore about 3 per cent more than our 5 per
cent rule for non-slave carrying vessels, meaning that Anstey's number of
1 Roger Anstey, 'The Volume and Profitability of the British Slave Trade, I76I-1807',
in S. L. Engerman and E. D. Genovese (eds.), Race and Slavery in the Western Hemisphere:
Quantitative Studies (Princeton, I975), 3-31.
2
BT.6/3 and Customs 17.
39
AH XVII
608
J. E. INIKORI
slave vessels or tonnage for this period is about 3 per cent too low. This
percentage may be regarded as small enough to be ignored. But, while
Anstey's total number of slave vessels or tonnage is only slightly low for
this period, his average number of slaves loaded per vessel is far too low
to be accepted. A total of 559,543 slaves loaded by 2,4I5 vessels gives 232
slaves per vessel. This is 15 per cent lower than the figure of 273 slaves per
vessel which I calculated from recorded export data relating to I67 vessels
which loaded slaves on the Gold Coastbetween I755 and I775.3 As noted in my
original paper, there is a substantialamount of evidence suggesting that if anything averagecargosize for the English slave tradein this period based on Gold
Coast data would rather understatethan overstate the true average cargo size
for all English vessels loading slaves from all parts of Africa. The evidence,
some of which I stated in my original paper,4 shows unmistakablythat the
larger vessels, loading very great numbers of slaves each, traded to the areas
beyond the Gold Coast-the Bight of Benin, the Bight of Biafra, Angolawhich formed the key centres of the English slave trade in the second half of the
eighteenth century. I therefore maintain that my estimates for this period,
and hence for the whole period 1750-80, are more accuratethan those of Anstey.
The remainingpart of our disagreementmay be discussedunder three periods
-I781-90;
I791-99; I800-7. In fact, my own corresponding periods, which
took into account the prevailingconditions at differenttimes, are I777-88 and
I789-i807. For the period, 1777-88, Anstey feels that my average cargo size
of 430 slaves is too high, preferringhis cargo size of 324 computedfrom British
West Indian import data. My reasons for suspecting the British West Indian
import data were stated in my originalpaper. In note 80 (pp. 213-14) of that
paper I gave some reasonswhy the averagecargo size for this period was high.
Those reasonshave to do with the generalconditionsfor the English slave trade
which prevailed during and shortly after the AmericanWar of Independence.
This was the period when some of the vessels belonging to John Dawson of
Liverpool were loading over 8oo slaves each. It was the notoriousovercrowding
of this period that partly led to the legislationof 1788 which imposed an upper
limit to the numberof slaves per ton. One of the main weaknessesof estimates
based on the BritishWest Indian import data is that they take no accountof the
much larger cargoes that went to non-British islands, particularlythe Spanish.
The largestvessels in the English slave tradein the late eighteenthcenturywere
owned by people like John Dawson of Liverpool holding special contracts to
supply the Spanish islands with slaves. A prominent Bristol slave merchant,
James Jones, pointed to this fact in I788,5 and further stated that English slave
traders with such contracts bought nearly four-fifths of all the slaves sold at
Bonny and New Calabar.6This is why I am convinced that ProfessorAnstey's
averagecargosize of 324 is on the low side.
However, since my sample covers only 5 years out of the I2 year-period,
I777-88, it is possible that it may not be accurate.If the erroris on the high side,
then the true averagecargosize should lie somewhere betweenAnstey's average
and mine, since it should be clear that the former is on the low side. A compromise, therefore, may be simply to take the mean between the two figures,
3 Inikori, 'Measuringthe Atlantic Slave Trade', 2II, Table 2.
4 Ibid. 213.
Ibid.
6 Ibid. 208.
MEASURING
THE ATLANTIC
SLAVE TRADE
609
being 377. This will reduce my estimate for the period, 1777-88, to 405,652
slaves exportedin English vessels, being the lowest I can accept.
For the remainingperiod, I789-I807, divided into two by Anstey, my reason
for makingit a single period in my originalpaper is the fact that the law of I799
did not state any specificslaves-per-tonratio,althoughthe new measuresimposed
may have had the effect of reducing the earlier ratio. The assumption upon
which I used the earlier imposed legal ratio for both periods is that the unrestricted larger cargoes which went directly to non-British islands, together
with the fact of evasion in the British islands would mean that using the legal
ratio for I789-99 would lead to a substantial under-estimate for that period,
which could then offset any over-estimatethat may arise from using the same
ratio for the period I800-7, if the law of 1799 reduced the ratio so much that
the greater cargoes to non-British islands plus violations in the British islands
failed to make it up. While the evidence suggests that the direct trade to nonBritish islands was more than the 25 per cent stated by Anstey, even at that level
its weight is not as light as Anstey suggests, depending on the extent to which
slaves-per-ton ratios among slave vessels trading directly to non-British islands
exceeded the legal maximum. I do not quite understandAnstey's point that my
'evidence about the ship Vanguardreally points more to the effectiveness of
cargo limitation' (p. 607). It was simply a matter of choice between two coststhe cost of purchasing the co-operation of colonial customs officials in the
British West Indies or the cost of acquiring foreign licences, which was often
little more than the actualcost of going to the continent before sailing to Africa,
and this could be more than offset by the higher prices for slaves in the nonBritish islands early in the nineteenth century. To say that a given customs law
is largely violated does not mean that some unlucky few do not get caught up
in it and suffer the penalty. Nor does it mean that to violate such a law successfully costs nothing.
In the final analysis,however, the importantpoint to be made is that Anstey,
having failed to take account of the direct trade to the non-British territories,
and having made no allowancewhatsoever for the unrecordedtrade for which
there is a substantial amount of evidence (to which I referred in my original
paper,7and to some of which Anstey himself has had occasion to refer8),has
to acceptthe fact that his estimatesare on the low side. From the presentexercise
my estimate for the whole period, 1750-I807, based on shipping data and under
the 5 per cent rule for non-slave carryingvessels, is 2,307,986 slaves exported
from Africa by way of the English trade. This may be comparedwith the result
obtainedbelow (p. 6I5), using a differentmethod and a differentbody of data.
II
Professor Curtin's comments on my paper fall into two broad parts. One
part is devoted to the question of who has a political motive, Curtin or Inikori.
That issue determined, the specific points treated in the second part are discussed as supportingevidence for the conclusionreachedin the first part.
The key to a proper understandingof Curtin's comments is his statement
7 Ibid.
8
208, 220-I.
Roger Anstey, The Atlantic Slave Trade and British Abolition, 1760-I81o (London,
I975),
I-12,
n. 31.
6Io
J. E. INIKORI
that what I said about his estimates and the data he used 'amounts to the claim
that I deliberately falsified the estimates so as to minimize the size of the trade.
Ordinary error without a political or other bias would be more random' (p. 595-6).
With this misconception it apparently became an emotional issue for Curtin to
defend his 'honour' at all cost. This accounts for the desperate tactics which he
adopted when I first presented my criticisms of his Census at a conference in
the United States in August I975,9 and the same tactics can be discerned in his
present paper, though now in a subtle form.
The logic which runs through Curtin's paper is that only 'a political or other
bias' can skew the frequency of error in a set of estimates in one direction.
Hence, if one can prove that one has no such ulterior motive, that proof at once
establishes the fact that one's errors ought to be random and so cancel each other
out, so that one's grand estimate must be accurate. Conversely, if you can show
that a man has 'a political or other bias', that by itself proves that the man's
results are wrong. Based on this logic, Curtin pleads that he had no
political or other motive to falsify the estimates (p. 596): if this is so, then
Curtin is right and Inikori is wrong; and if Inikori is wrong it is because he has
a political or other motive.
The naivety of this logic is too obvious to warrant much comment. Suffice it
to say that the frequency of error in a set of estimates can be skewed in any
direction for several reasons that have nothing to do with 'a political or other
bias'. And, for that matter, a man can have a political motive and yet produce
an accurate estimate. Hence, whether Curtin/Inikori has a political motive or
not is immaterial to the issue in hand.
The specific points treated in the seemingly academic part of the comments
can be handled one at a time. The first point is that my 'criticism of a book that
was explicitly written to be revised' (p. 595) is unnecessary. It is true Curtin
stated that the book 'will be modified in time as new research produces new
data','1 and I stated this in my original paper." But since this declaration of
intent is followed later by the very strong conclusion that 'it is extremely unlikely
that the ultimate total [number of slaves imported] will turn out to be less than
8,ooo,ooo or more than Io,500oo,ooo',12 there is certainly no reason why Curtin's
figures should not be quoted by later writers with a high degree of certitude.
Curtin is certainly aware of the fact that those figures have been widely quoted
in that manner since the appearance of his book. Apart from Curtin's emphasis
on the accuracy of his estimates, he in fact makes it clear where he expects the
direction of error, if any, to be. 'While it is doubtful that the revised estimates
are too low', we are warned, 'it is easily possible that they will be too high'.13
And this warning that the estimates in the book are too high is constantly
repeated throughout the book. It is these misleading assertions in the book that
my original paper tried to correct. And I have no doubt whatsover in my mind
that this is a legitimate historical exercise.
Curtin complains that I misrepresented the main historical problem tackled
9 Mathematical Social Science Board Seminar on the Economics of the Atlantic Slave
Trade, 20-22 Aug. 1975, at Colby College, Waterville, Maine, U.S.A.
10 Curtin, Census, p. xviii.
1 Inikori, 'Measuring the Atlantic Slave Trade', 197.
12
Curtin, Census, 87.
13 Ibid. 86.
MEASURING
THE ATLANTIC
SLAVE TRADE
6II
in his book when I wrote in my originalpaperthat 'The main historicalproblem
which Curtin's Censusis intended to solve relates to the total number of slaves
exported from Africa by way of the Atlantic slave trade during its entire period.
Other related questions treated in the book include the proportionatecontribution of specified African regions to the estimated total numbers exported; the
distributionof the total numbers imported among the importing regions in the
Atlantic; and the distributionof the total numbers exported and imported over
time'.14But in his present paper (p. 595) Curtin himself says that 'The Atlantic
Slave Trade:A Censusappearedin I969 as an effort to bring together what was
known in the mid-Ig60s about the origins, numbers, and destinationsof people
who moved out of Africa in the greatest inter-continentalmigration that had
taken place up to that time'. Putting these two statementsside by side I do not
quite see where the misrepresentationoccurs.
Curtin amuses me when he suggests (on p. 596) that my attempt to estimate
more accurate figures of slaves exported from Africa has no use in African
history other than in defending or condemning the moralityof the slave trade.
Had this been the case few serious Africanistswould have concernedthemselves
with the question of the number of slaves exportedfrom Africa. But in fact this
is not the case. The acquisitionand export of people as slaves from Africaduring
a period of over four hundred years constituted an important factor in the
historical processeson the continent. For this reasona proper understandingof
those historical processes requires that an accurate estimate of the number of
people exported as slaves be obtained along with other historicalfacts. This was
why I thought it worth while to correct the misleading assertions in Curtin's
Census.If a desire to make a humble contributionto a proper understandingof
Africanhistory is what Curtinrefersto as the ulteriormotive behind my original
paper then he is very correct.
It is appropriateat this juncture to show one of the majorfactorswhich helped
to skew Curtin's set of estimates to the low side. This is his view of the degree
of fluctuationin the Atlantic slave trade. He holds that the one-year estimates
of total slave exports or imports made by some contemporaryobservers are
accurate for the particular years to which they apply.15'They only become
inaccurate if they are misinterpreted as long-term averages-but they are
nevertheless responsiblefor many of the high estimates of the total slave trade
found in the historicalliterature'.6Curtinarguesthat this is so because 'the trade
varied greatly from year to year' so that if the one-year estimates which are
usually for peak years are treatedas period annualaveragesthe estimates will be
inflated. He concludes that if the one-year estimates are treated as the greatest
single year figures in given periods, 'they are in close agreement' with his
estimates.17
A great deal of Curtin's argumenthere is correct, with the exception of the
last part. The volume of the slave trade, like any trade, fluctuatedover time, and
Curtin is right in drawingattentionto this fact. But he in turn is unawareof the
extent to which he exaggeratedthe degree of fluctuation in the Atlantic slave
trade. And this exaggeratedview-to my mind a genuine mistake on the part of
Curtin and nothing to do with 'a political or other motive'-considerably
14
Inikori, 'Measuring the Atlantic Slave Trade', 197.
15 In fact, many of these estimates were based on official data.
16
17 Ibid.
Curtin, Census, I49.
J. E. INIKORI
6I2
influenced his judgment throughout his book. Some examples will be given
later. For the moment, we will illustrate the point by examining Curtin's
comparison of his export estimates for the English slave trade of the eighteenth
century with the one-year contemporary estimates for the same period.18
In Table 42 of the Census, Curtin shows against the relevant years one-year
contemporary estimates of the number of slaves exported from Africa by
English merchants. He tries to show what happens when these one-year estimates
are treated as period annual averages, by using them as such for stated periods.
He then compares the result with his own estimates. The second part of the
comparison is between his own annual averages for the same periods with the
one-year estimates treated as annual averages for the stated periods. In the end,
he explains the differences in both cases in terms of the year-to-year variation
in the volume of the English slave trade, the one-year estimates applying to the
peak years. This means that if Curtin's estimated annual averages for the given
periods are expressed as percentages of the relevant one-year estimates this will
give a measure of the degree of fluctuation in the English slave trade during the
stated periods. This is shown under column (5) of Table i(a) below.
TABLE i(a)
A comparisonof the degree of fluctuationin the Atlantic slave trade computed from the
official value of commodityexports from Englandto the Africancoast, I70I-1807, with
the degree of fluctuationshown in Curtin's Census
(I)
Total
export
per
period
?
Period
170o-22
(22)
1723-36 (I4)
1737-58
(22)
1759-69 (I )
1770-3 (4)
1774-80 (7)
1781-93
1794-1807
(2)
(I3)
(14)
Period
mean
export
value
?
(3)
1,96I,130
89,142-272
1720
192,059-71
1725
I83,317
4,842,652
2,812,049
2,851,902
9,I22,344
440,24I-09
I3,183,720
(5)
130,351
284,025
68-39
39-o6
32-72
I98,439
6I2,392
92-38
Curtin'speriod
mean estimate
as a percentage
One-yearexport
of one-year
value treated
as period
(2) as figurestreated
mean
% of (3) as periodmean
?
%
%
2,688,836
4,032,974
(4)
I749
67.62
59-86
5I.22
703,012-25
I768
I77I
712,539
71-89
98-66
407,414-57
I775
786,169
51-82
701,718-76
I787
727,634
96-44
85-79
941,694-28
I798
84-40
59-27
I,I115,793
4I-53
47.8o
Sources and notes: Columns(I), (2), (3) and (4) are based on Appendix I below, where the
sources are shown. Column (5) is computed from Table 42 of Curtin, Census, 148. The
computationwas made by expressingcolumn (4) of thattable as a percentageof column (I)
of the same table.
In order to show that column (5) of Table i(a) is an exaggeration of the
degree of fluctuation in the English slave trade of this period I have calculated
a parallel index of fluctuation from the yearly official value of commodity exports
from England to the African coast, 170I-I807, adapted exactly to the method
adopted by Curtin in constructing Table 42 of the Census. Since the official
values of the commodity exports were based on constant prices established at the
beginning of the eighteenth century, they are in fact measures of volume rather
than value. I showed in my original paper that the official records understated
18
Ibid. I46-9, and Table 42, p.
I48.
MEASURING
THE ATLANTIC
SLAVE TRADE
6I3
the value and volume of goods actually carriedto the African coast by English
slave merchants.19This cannot have any effect on the use of these officialfigures
in measuring the degree of fluctuation in the trade. The year-by-year values
from which the table was constructed are shown in Appendix I below. The
periods in Table i(a) are exactly the same as those of Curtin in Table 42 of the
Census,and the one-yearexport values shown under column (3) are for the same
years for which Curtin showed his one-year estimates. Column (I) shows the
total value of commodity exports in each period; column (2) shows the annual
average for each period; and column (4) shows the period annual averages
expressedas percentagesof the relevantone-yearexport values in order to show
the degree of year-to-yearfluctuationin the volume of the trade.
If Curtin's views of the degree of fluctuationin the Atlantic slave trade are
correct the degree of fluctuationshown by his estimates should agree, at least
roughly, with the one calculated from the year-by-year real measures of the
volume of the trade as shown in column (4) of Table I(a). In fact, for every one
of the periods Curtin'sestimatedperiod annualaveragesform lower percentages
of the one-year figures than the equivalent percentages calculated from commodity exports. Apart from the two periods, 1774-80 and 1781-93, where the
percentages are fairly close to those of Curtin-51.8 and 47.8, 96-4 and 85-8,
respectively-Curtin's estimates exaggeratethe degree of fluctuationfor all the
other periodsroughlyby a factorof two.
This exaggerated view of the year-to-year variation of the volume of the
Atlanticslave tradewas a decisive factorwhich helped to push Curtin'sestimates
to the low side. This is particularlyso for the estimates relatingto the first two
and a half centuriesof the tradefor which evidenceis ratherscanty. For example,
Jan Vansina stated that by I530 slave exports from Angola were running at an
annualfigure of four to five thousandslaves and 'if there were no more, this was
due only to the lack of ships to carry them'.20 Under the influence of his
exaggeratedview of the year-to-yearfluctuationin the volume of the slave trade,
Curtin argued that 'this figure is too high to have been sustained for a full
quarter-century'and so reduced it arbitrarilyto 750 slaves per annum, the
latter figure being a mere 16-7 per cent of the one reported.21Under the same
influence, Curtin persuaded himself that at the criticaljuncture of the French
RevolutionaryWar in I794 'no ships at all sailed to Africa from England',22
when in fact 155 ships, measuring29,473tons, sailed from Englandto the African
coast in that year.23This same influence is discernible in Curtin's choice of
estimates made by different writers-he tends to suspect authors with high
estimates and to prefer authorswith fairly low estimates. For example, he states
variousestimatesof Brazilianslave importsmade by variousauthors-50 million;
15 million; 6-8 million; 5,750,000; 3,500,000; 3,600,000; 3,500,000-3,600,ooo.
19 Inikori, 'Measuring the Atlantic Slave Trade', 205-6.
20
Jan Vansina, Kingdoms of the Savanna (Madison, I966), 53. See also David Birmingham, Trade and Conflict in Angola: The Mbundu and their neighboursunder the influence of
the Portuguese, 1483-I790 (Oxford, I966), 25-6.
21
Curtin, Census, 99.
22 Ibid.
I35. Curtin does not state the source of his information. But it is probable that
he based this conclusion on a table in Gomer Williams, History of the Liverpool Privateers
and Letters of Marque (London, I897), 678, in which 1794 is left blank. This simply
means that the author had no information for that year.
23 Customs I7/i6, fo. 9.
J. E. INIKORI
614
In the end he chose the figure of 3,646,800 as the number of slaves imported
into Brazil during the entire period of the slave trade.24 Examples of how
Curtin's exaggerated view of the year-to-year fluctuation in the volume of the
Atlantic slave trade affected his estimates can be multiplied. But the examples
stated should be enough to make the point.
Returning to Curtin's estimates of English slave exports of the eighteenth
century, the real measures of fluctuation calculated from the complete time series
of commodity exports and shown under column (4) of Table I(a) above, can
in fact be used as deflators with Curtin's estimate of slave exports using one-year
contemporary estimates as period annual average, shown under column (3) of
Table 42, in the Census.25 The use of these deflators eliminates the error in
using the one-year estimates as period annual averages owing to the degree
of year-to-year variation in the volume of the English slave trade, the one-year
estimates applying to 'good' years. The result of this exercise is shown in
Table I(b) below. Column (i) of the table is taken from column (3) of Curtin's
Table 42, and column (2) is taken from column (4) of Table I(a) above. The
exercise produced a total English export of 3,699,572 slaves for the whole of the
eighteenth century, as against Curtin's preferred estimate of 2,480,000 for the
same period.26
TABLE i(b)
Period
(I)
(2)
(3)
Estimated slave
exports using
one-year figures
as period mean
Deflator
Deflated
estimate
1701-22
1723-36
792,200
607,600
1737-58
937,200
0-9238
865,781
1759-69
584,100
0-7189
419,902
1770-3
1774-80
i88,8oo
287,000
0.9866
0-5I82
186,276
148,731
1781-93
494,000
0o9644
476,406
1794-1807
770,000
o.8440
649,856
4,662,900
0o6839
o-6762
541,757
410,863
3,699,572
Sotrces: Column (i) taken from Curtin, Census, Table 42, column (3), p. 148.
Column (2) taken from Table I(a) column (4) above.
In order to obtain an equivalent component of Table i(b) that can be compared
with my estimates for the period, 1750-I807, I tried to compute the proportion
of the estimate for the period 1737-58 that can be assigned to the period I750-8.
This I have done by adding the total value of commodity exports for the two
periods from Appendix I below. For the period, I737-58, total exports add up
to ?4,032,974; for the period 1750-8, the total is ?1,806,609. Thus, commodity
exports for the latter period made up 44.8 per cent of the total export for the
period, I737-58. Using this percentage with the deflated estimate of 865,78I
for the period, I737-58, gives 387,870 slaves for the period I750-8. Adding
24
25
26
Curtin, Census, 48-9.
Ibid. 148, Table 42.
Ibid. 142, Table 41, column (5).
MEASURING
THE ATLANTIC
SLAVE TRADE
6I5
this to the deflatedestimate for the period, 1759-1807, gives a total of 2,305,04I
slaves for the period, 1750-I807. This comparesvery closely with my estimate
of 2,307,986 shown above (p. 609), which is based on an entirely differentbody
of official data and different method of computation. This is particularlyreassuring. It shows the level of accuracy to be expected from both estimates.
Above all, it shows that the one-year contemporaryestimates were based on
official records. As Curtin rightly points out, they only become inaccurate if
they are used as long-term annual averages.But the comparisonwith Curtin's
preferredestimate also shows that if one exaggeratesthe degree of fluctuationin
the volume of the slave tradethe errorshifts from one extremeto another-from
a gross over-estimateto a gross under-estimate.
Curtin claims that what I attemptedin section II of my originalpaper simply
repeatedwhat had alreadybeen done by Anstey and accepted by himself. Any
one who has read my paper and Anstey's will know that this is simply not true.
Not only are my estimatesfor comparableperiods higher than those of Ansteya point over which some agreementhas been reachedbetweenAnstey and myself
-but in fact I treated periods and discussed some very important matters in
section II of my paper which were completely untouched by Anstey.
What is rathercurious is Curtin'sargumentthat the export estimateshe made
in the Censuswere not intended to support his calculationsof the total volume
of the slave trade, so that if they are proved to be too low, no matter what the
magnitude of the error may be, that will not have 'the slightest bearing' on the
credibility of his grand estimate, since the latter 'was based entirely on import
data' (p. 596). It is obvious enough that this argumentis simply unacceptable.
But since Curtinhas put it forward,two brief commentsmay be offered. Firstly,
many readersof the Censuswere persuadedto accept Curtin'smisleadingassertions in that book because of the apparentagreementbetween his import and
export estimates, especially those for the period I761-1810. Secondly, it was
exportsthat laterbecameimports, and no equationwith unknownscan be said to
have been correctlysolved when on substitutingfor the unknownsthe two sides
of the equation fail to agree.
In various sections of my original paper I showed that Curtin's various
estimatesof import and export figuresof slaves, and in some cases Anstey's also,
were too low because the official data employed systematicallyunderstatedthe
measures used, for reasons stated at length. This argument related to slave
population and slave import figures in the Americas; slave smuggling and the
inaccuracyof officialslave export data in PortugueseAfricanterritories(Angola
and Mozambique); understatementby the customs records of the volume and
value of commoditiesemployed by English merchantsin the purchaseof slaves
on the African coast, as well as the number or tonnage of shipping employed.
I broughtforwarda large amountof historicalevidence to bear on the argument.
One or two more examplesmay be added.
In i8o6, in response to a request from the British House of Commons, the
Inspector General's Office preparedan account of British iron and iron wares
exportedto all countriesfor ten years(1796-I805), based on very thoroughwork.
The African figures produced give a fair measure of the extent to which the
Customs records (Customs 3 and 17) understatethe volume and value of commodity exports to the African coast in the eighteenth century. These figures are
shown below in Table 2(a).
616
J. E. INIKORI
TABLE 2(a)
A comparison between Customs figures and account prepared for
the House of Commons by the Inspector General's Office in I806
Year
Customs
book figures*
Account prepared for
House of Commons
Official valuet
Real value:
?
?
?
129,026
1796
22,382
73,020
1797
66,374
69,644
117,I07
1798
32,282
85,I30
147,284
1799
1800
I80o
27,630
22,383
29,049
I7,699
94,78
ioI,206
208,415
I70,884
180,676
1802
ioo00,680
I01,92I
186,057
1803
1804
1805
60,824
90,651
70,765
60,513
89,793
69,849
II0,38I
I61,91O
127,944
Sources and notes: *Cust. 17/18-27; t and $, Br. Parl. Papers, Accts. & Papers, I806,
vol. xII, nos. 439, 441 and 443. Customs Book figures are usually in official value. The
i806 accounts were made for individual products. The aggregate figures shown in the
table were made by adding them up.
The customs book figures, being in official values,27 are directly comparable
with the official values of the accounts prepared for the House of Commons in
I8o6. The difference between official values in the customs books and the
official values of the I806 account arises from the omission of certain iron products
in the customs accounts. The 'real values' in the i806 account were calculated by
the Inspector General's office by using current prices. Hence, the difference
between this column and the Customs book values is a fair example of the underrecording and under-valuation to be taken into account while using Customs 3
and 17 as sources for measuring the volume of English exports to the African
coast in the eighteenth century. In fact, Professor J. R. Harris of Birmingham
has also shown the same phenomenon in the case of British exports to the East
Indies.28
With regard to the phenomenon of slave smuggling in Portuguese African
territories, this has been strongly stressed by many studies on this area. To cite
one piece of evidence among many, in I826, the captain of a British cruiser
anchored in Mozambique wrote:
Between eight and ten thousand [slaves] are entered at the Custom house
annually as being exported from the Port of Mozambique to the Brazilshowever, I consider that about i or more may be added to that number as
being shipped off to the Brazils in these vessels. This additional fourth
is smuggled on board to cheat the Custom house.29
27 The 'official values' in Customs 3 and 17 were based on constant prices of commodities exported, which were established at the beginning of the eighteenth century.
28
J. R. Harris, The Copper King: A Biography of Thomas Williams of Llanidan (Liverpool, 1964), iI.
29 P.R.O., C.O. 415/7, A. no. 172, pp. I2-I3,
Capt. Acland's Journal no. 2, MoC.,
9 Oct. i826, quoted by Edward A. Alpers, Ivory and Slaves in East Central Africa:
Changing Patterns of International Trade to the later nineteenth century (London, 1975), 2I2.
MEASURING
THE ATLANTIC
SLAVE TRADE
6I7
The amount of historicalevidence supportingmy argumentin this aspect of
my original paper is really so substantial that only Curtin's ignorance of the
historicaldata can make him write in the way he does. Generalstatisticaltheory
of randomerrordoes not take precedenceover historicaldata. If this were so all
the efforts made by careful historiansto discover the errorsin officialstatistics,
particularlythose for the eighteenth century and earlier, would be declared
superfluous.Argumentsabout the inaccuracyof officialrecordsbased on a large
amount of historical data can only be countered with opposing historical data,
not with vague theoriesof randomerror.
In my original paper evidence from government committees, government
officials and some contemporarywriters who carried out detailed researchwas
quoted to support some arguments in different places. In his usual resort to
vague general arguments, Curtin denounces my use of this kind of evidence.
But, in fact, in other parts of his paper he acceptsthe same pieces of evidence he
condemns. For example, I quoted the evidence of James Fuller and that of the
Council and Assembly of Antigua in connexion with the unusually heavy slave
mortality of the I770s and I78os in all the Caribbeanislands. Having attacked
me for relying on this kind of evidence, Curtin, later in his paper, accepted this
evidence and used it in his argument(p. 6o0). Again, I quoted the Committee
of the JamaicanHouse of Assembly in connexion with the understatementof
Jamaicanslave population by the tax rolls. In the same manner, after raining
abuse on Inikori for accepting such evidence, he later accepts it and uses it in
his argument(p. 600). In fact, all the statementsmadeby governmentcommittees
or governmentofficialswhich I quoted in my originalpaperwere based on actual
investigations. Governor Crew's statement of I708 actually included measured
data-that it annually required an import of 3,640 slaves or about 7 per cent
to keep up the stock of slaves in Barbados.30My referenceto Governor Crew's
evidence was not intended to mean that the 7 per cent rate ought to have prevailed in the Leeward islands during the entire period, 1707-33. Its proper
meaning,which I am sure will be clearto otherreaders,is thatif the Barbadianrate
prevailed in the Leeward islands by about 1708, then an averagerate of 1-2 per
cent for the latter islands during the whole period is incredible. There was no
suggestionin my paperthat GovernorCrew intended his statementto be applied
to the Leewardislands,nor that he was stating what was to happen in the future.
It is clear in my paper that the inter-islandand inter-temporalcomparisonsare
mine, following Curtin'sown method.
With regard to the French territories, the name of the French planter in
Saint-Domingue, referred to by Curtin as 'an anonymous French planter'
(p. 597), is in fact stated in various parts of my original paper in the footnotes
to the evidence used. This is the planter, Hilliard D'Auberteuil,who published
in I776 and I777 a two-volume work on Saint-Domingue, based on thorough
investigation, as he stated himself.31In his book Hilliard d'Auberteuilactually
made some detailed calculationsbased on import data, some of which I stated
in my originalpaper.32His book was widely read in Britain.James Fuller, whose
30British Parl. Papers, Accts & Papers, 1789, vol. 84, part IV, Supplement to no. 15,
no. 3, Barbados.
"1Michel Rene Hilliard d'Aubertueil, Considerations sur l'Etat Present de la Colonie
Franfaise de Saint-Domingue (2 vols., Paris, 1776 and 1777).
32
Inikori, 'Measuring the Atlantic Slave Trade', 204 and 221.
618
J. E. INIKORI
evidence Professor Curtin used for a large part of his Jamaican estimates,
described the book as the work of a 'respectable planter', and the evidence as
'entirely disinterested', and stated that its 'veracity has never yet been impeached'.33
On French-carried slave exports, Curtin refers to Captain George Hamilton's
'miraculous breadth of knowledge and Inikori's trust in it' (p. 605). On page 206
of my original paper I described the extent of trade carried on by the slave
trading firm of which Captain George Hamilton was the resident 'general
manager'. This was the 'Floating Factory' venture by Thomas Hall & Co. of
London. Between I732 and I743 the firm carried on a very extensive slave trade,
with about eight ships permanently stationed on different parts of the African
coast, each under an officer and all under the general management of Captain
George Hamilton. Apart from the stationed ships the firm employed a large
number of small vessels in collecting slaves from large parts of the African coast.
For the whole period of the venture Captain George Hamilton resided in West
Africa. The activities of this firm are well documented by the firm's records
in the P.R.O. to which reference was made in my original paper. Some idea
about them can also be found in C. Gill's book, Merchants and mariners of the
eighteenth century (I96I). Curtin wants us to prefer his own guesses which have
been found to be seriously erroneous to evidence from a man in Captain George
Hamilton's position.
The issue, therefore, is not whether 'the opinion of any contemporaneous
observer... is to be preferred to calculations based on measured data' (p. 596).
Rather, it is whether the views of well-placed contemporaries based on thorough
investigation and personal knowledge are to be preferred to estimates based on
incomplete and inaccurate data and the use of a questionable method.
Curtin's other point relates to my criticism of the formula he employed in the
Census. I argued in my original paper that the use of only two slave population
figures (one at the beginning and the other at the end of the period) to calculate
the annual average growth rate of the slave population over a long period of
years during which the slave population figures fluctuated radically due to heavy
mortalities arising from various causes, and more or less made up with large
imports from Africa, will lead to an inaccurate result.34 Professor Curtin thinks
that this argument arises from 'an elementary misunderstanding' on the part of
Inikori (p. 598). This is rather strange, since my criticism is based on an elementary rule about the computation of the average. But since Curtin has
confessed his ignorance of this elementary rule, my argument is illustrated in
Table 2(b) below.
The annual average growth rate of this hypothetical slave population from
I76I to I780, a period of twenty years, is actually I-2 per cent. But taking the
slave population figures at the beginning and end of the period, and using
Curtin's formula, the annual average growth rate is zero. The experiment can
be varied ad infinitum to produce greater and greater magnitudes of inaccuracy,
bearing in mind the conditions described in my argument. In fact, in this
particular instance, r and T, population growth rate and total slave imports,
respectively, both become zero in Curtin's formula.
33
34
BT. 6/IO, p. 83, Evidence of James Fuller, 1788.
Inikori, 'Measuring the Atlantic Slave Trade', I98.
MEASURING
THE ATLANTIC
SLAVE TRADE
619
TABLE 2(b)
An illustration of the inaccuracy that may be produced by using the compound interest
formula in computing the annual average growth rate of a slave population over long
periods of time during which the slave population figures fluctuated radically.
(I)
(2)
Year
Slave population
Year-to-year rate of
increase positive or
negative
1761
I00,000
1762
120,000
I76I-2
1763
1764
1765
1766
1767
I768
1769
1770
I77I
I30,000
140,000
130,000
140,000
150,000
i6o,0ooo
I8o,ooo
i6o,000
I50,000
1762-3
1763-4
1764-5
1765-6
1766-7
767-8
I768-9
1769-70
I770-I
1772
i6o,ooo
I77I-2
6.7
I773
1774
I70,000
i80,000
I772-3
I773-4
6.25
1775
200,000
I774-5
1.I
I776
1777
250,000
260,000
1775-6
1776-7
25-0
4-0
1778
200,000
I777-8
I779
1780
150,000
i00,000
I778-9
1779-80
Annual average growth rate, 176I-80
%
oI0585
= -128.9525=
20
20-0
8.3
7.7
-7-I
7-7
7.I
6.7
I2.5
-II-I
-6.25
5-9
-23-1
-25-0
-33'3
-2%
In another part of his paper, Curtin refers to the Barbadian example I gave
to show the kind of inaccuracy that may be associated with the choice of terminal
dates in using his formula.35 Curtin tries to show that the magnitude of the error
is very small by expressing the error as a percentage of the total import estimate
for Barbados (p. 603). This misses the point completely. The magnitude of
error to be measured relates only to the period, I645-72, for which the accuracy
of results obtained with the use of the formula, in connexion with the choice of
terminal dates, is being tested. For this period, Curtin's estimate in the Census
gives 56,800 slaves,36 based on his choice of terminal dates. Curtin has now
accepted that if he had used different terminal dates he would have obtained an
additional figure of I4,000 slaves for the same period. The magnitude of error
in using the formula for Barbadian imports in this period is, therefore, 24.6 per
cent. What I was trying to do in this part of my original paper has really nothing
to do with the total Barbadian slave import estimates. Had Curtin read that part
of the paper carefully, this point would have been clear to him. The implication
of my argument there is that
producing this magnitude of
found in Curtin's Census.
In several parts of his paper
paper. This is particularly so
35 Ibid. I99.
no serious historian using a formula capable of
error should make the kind of assertions to be
Curtin shows a complete misunderstanding
of my
with his complaint about my use of his formula
36
Curtin, Census, 59.
J. E. INIKORI
620
which I criticized (p. 599). The argument throughout my paper, explicit and
implicit, is that this formula has an inbuilt tendency to under-estimate the
number of slaves imported, given the conditions which prevailed among the slave
populations. I demonstrated why this should be so. By using this same formula
myself in some cases the purpose is really to emphasize how low Curtin's
estimates in such cases actually are, since they can be shown to be lower than
estimates obtained through a formula that has an inbuilt tendency to underestimate.
Curtin's other comments relate to the annual rate of net natural decrease
among the slave populations in the Americas. Here Curtin completely misunderstands my argument. In no part of my paper did I say that if the computed
rates of decrease are too low this is due to population figures that are too low.
I made it abundantly clear that if the computed rates are too low this may mean
that the slave 'import estimates employed in the calculation are wrong or some
other things may have gone wrong with the computation'.37 I argued at length,
bringing facts and figures to bear on the argument, why Curtin's Jamaican rates
applied to the Leeward islands of the British Caribbean, 1-2 per cent for the
years I707-33, and to Saint-Domingue, 1.9 per cent for the years I779-90, are
too low.38 With regard to wrong slave population figures, the import of my
argument, of course, is that using such low rates of net natural decrease with
slave population figures which are again too low substantially under-estimates
the total number of slaves imported. It is therefore clear that all Curtin's
comments in this regard (pp. 60I-3 and Table i) have no bearing whatsoever on
my argument.
With regard to estimates relating to the French West Indies, Curtin distorts
my argument relating to slave population figures there in order to make his
task easy (p. 600). I reproduce below the relevant portion of that argument,
which can be compared with Curtin's distortion:
As for the French West Indies, if the French colonies were as inefficient in
their administration as the ancien regime in their mother country was at
that time, then one should expect them to provide far less accurate slave
population figures than the British colonies. In fact, the slave owners in
Saint-Domingue are said to have made the declaration of the number of
their slaves for purposes of the 'capitation des Negres' with considerable
fraud.39
The weight of the whole argument is, of course, on the last sentence, the fact
that the slave owners in the French territories, like their counterparts in the
British, Spanish, Portuguese, and the other territories, understated the number
of their slaves to the government officials in order to avoid the payment of heavy
taxes. This was a general phenomenon in all the slave-holding territories in the
Americas where slave owners paid taxes on the number of slaves held. It did
not matter whether the slave population figures were taken directly from tax
returns, or from ordinary census returns drawn up by slave owners, since the
slave owners constantly had their minds on taxes to be paid on the number of
slaves held. The point about inefficient or efficient administration is simply
that the greater the degree of inefficiency in administration, the greater the ease
37
38
Inikori, 'Measuring the Atlantic Slave Trade',
Ibid. 201-3.
202.
39
Ibid. 200.
MEASURING
THE ATLANTIC
SLAVE TRADE
62I
with which tax evasion occurred, and so the degree of error in this respect, in
relationto slave populationfiguresofficiallyreported.
This is why Curtin's explanation-that the ratio of his estimated slave
imports to slave populationin the French West Indies is lower than that of the
BritishWest Indies becausethe populationfiguresin the latterwere understated
(p. 6oo)-is unsatisfactory,since the same point appliesto the French territories.
Also, Curtin's argument that the I78os were a period of high prosperity for
Saint-Domingue, but of disasters for Jamaica,and so the Jamaicanrate of net
naturaldecreaseis applicableto Saint-Dominguein that period (p. 6oi) does not
hold water. On footnote 23 of my originalpaper I stated that the report of the
JamaicanHouse of Assembly's Committee of 1788 says that the French and
Spanish islands also lost slaves from the disastersof the late I77os and I78os.40
On the otherhand, Curtinprovidesno explanationfor his applicationof Jamaican
rates of decrease for the period I673-I729, to Saint-Domingue for the period
I68I-I738. During those respective periods, Jamaicanslave populationgrew at
an average rate of 3-7 per cent p.a., while that of Saint-Domingue was 7 per
cent.41 Again, the argument that Curtin's import estimates for the British
Caribbeansare too high rather than the estimates for the French West Indies
being too low (p. 6oi) is unacceptable.In the first place, Curtin has not given a
satisfactoryexplanationwhy his import estimatesfor the British West Indies are
12 per cent lower than those made by Stetson for the same territories.42In the
second place, the magnitude of error in Curtin's estimate of the volume of the
British-carriedslave export shows beyond any reasonable doubt that even if
only 50 per cent of the British-carriedtrade went to the British territoriesthe
total should still be largerthan Curtin'simport estimatesfor those territories.
As to Curtin's reference to the official import figures for the French West
Indies in 1787 and I788 (p. 6oi), to be found in Peytraud'sbook, either Curtin
has not read this book himself or there is an errorin his notes from it. Below is a
translationof the relevantsection of that book (see footnotebelow for the original
in French):
A list of the French trade in I785 shows an importationof 34,045 blacks
for Saint-Domingue alone from the West Coast of Africa, without taking
account of at least 3 or 4,000 importedfrom the coast of Mozambique.We
know that, for 1787, the actual import was 3I,171, and for 1788, 30,097.
In 1789, one author wrote, 'our colonies export each year from Guinea
36,5oo negroes.'43
From Peytraud'sdata, about 37,500 slaves were imported into Saint-Domingue
alonein 1785 by way of the French carriedtrade. My understandingof the 1787
and I788 figuresis that they arealso for Saint-Dominguealone, not all the French
islands. Curtin's argument (p. 6oi) is therefore out of line with the data
of the authorhe cites. The other point is that the officiallyrecordedimports for
Saint-Domingue relate only to French-carriedtrade, slaves carried to that
41 Ibid. 203.
42 Ibid. 203-4.
Ibid. 202, n. 23.
43 'Un tableau de la traite
frangaise en 1785 indique une importation de 34,045 noirs des
40
cotes occidentales d'Afrique uniquement pour Saint-Domingue, sans en compter au
moins 3 ou 4,000 expedies des c6tes de Mozambique. Nous savons que, pour 1787,
l'introduction reelle a ete de 31,171, et pour I788, de 30,097. En I789, ecrit un auteur,
"nos colonies exportent chaque annee de la Guinee 36,500 negres" ': L. Peytraud,
L'Esclavage aux Antilles Franfais avant 1789 d'apres des documents inidits des Archives
Coloniales, These Presentee a la Faculte des Lettres de Paris (Paris, i897), I39.
J. E. INIKORI
622
island by other nationals being usually smuggled into the island. The volume
of that branch of the import was estimated by Hilliard D'Auberteuil at an
annual average of 4,000 slaves during the period I767-73.44
My suspicion that Curtin has not actually read Peytraud's book is confirmed
by his suggestion that the 452,000 slave population figure I stated for SaintDomingue, c. 1780 is either my own 'fabrication' or 'that of the author' I cited
(p. 600). The author I cited, of course, is Peytraud. And the information is well
laid out on the same page (p. I39) which contains the 1787 and 1788 figures
cited by Curtin. Because of Curtin's allegation, I have arranged for the relevant
portion of Peytraud's text to be printed as Appendix III to this paper. It is also
possible that it is because Curtin did not read Peytraud's book, based on a
doctoral thesis, that he could not relate his own estimate of 1,600,200 to the
3 million slaves stated by Peytraud as a conservative estimate of total imports
into the French West Indies.45
Curtin complains about my remarks relating to imports into Spanish America
on the ground that the remarks are based on slave population figures without
evidence as to natural increase or decrease (p. 603-4). It is clear enough that during
the period in question rates among slave populations (including newly imported
Africans and others), outside the United States, were decreasing, although there
may be a problem in determining the precise figure. Hence, when the figures
I cited from Ralph Davis and those I got from archival sources46 are compared
with Curtin's estimated import figures, it is commonsensical to conclude that
Curtin's estimates are too low.
In the case of Brazil, Curtin made two important suggestions. One is that the
black population figures I cited are wrong because they come from 'authors of
a popular history of the slave trade' (p. 604). The other is that manumission was
widely practised by Brazilian slave holders (p. 604). As to the latter point,
Professor R. B. Toplin, in his recent book, has shown that the whole idea of
manumission being widely practised by Brazilian slave holders arose from
stage-managed propaganda by those slave holders. As he states, 'cases of manumission could easily be advertised for partisan purposes. ... In reality, manumissions did not effect significant diminution of the total slave population;
they only gave the institution the appearance of decline because of the publicity
that attended emancipations.'47 As to the accuracy of the figures I cited, if we
assume that they are too high this may mean that the Brazilian slave imports
of the eighteenth century and before are lower than the present numbers
indicate. But this does not help Curtin's case, because if the 1798 figures are
small, when used with the known figures of the mid-nineteenth century, the
result does not help Curtin's argument. For the period, I873-87, the following
Brazilian slave population figures are provided by Toplin48:
I873
1875
I878
I883
1,566,416
1,419,966
1,368,097
1,346,648
I884
I885
I887
44Inikori, 'Measuring the Atlantic Slave Trade', 221.
1,240,806
1,133,228
723,4I9
46Ibid.
45Ibid. 204.
47RobertB. Toplin, TheAbolitionof Slaveryin Brazil (New York, 1972), i8.
48 Ibid. 21, Table i. Toplin's source is the Relatoriosof the Minister of Agriculture,
Commerce,and Public Works.
MEASURING
THE ATLANTIC
SLAVE TRADE
623
Toplin points out that these figures understate the true slave population in
the given year:
Governmentagents had great difficultyconductinga census of slaves in the
empire because of the problems involved in obtaining accurateinformation
concerning isolated plantationsand the reluctanceof some slaveholdersto
co-operate. In all the reports, ministers indicated that the returns did not
include figures from certain communities, many situated in important
slave-holdingareas.49
However, they may still be used as a rough approximationof the true situation.
Since the trend is downward, the figures for I850 ought actually to be higher
than those for I873. But for the sake of argument, let us assume the slave
populationfigure for 1850 is the same as the one for 1873. We may reduce the
figures I cited for I798 by half (although Curtin would want them reduced
further,which will, in fact, make our estimateshigher still), so that the Brazilian
slave population for I801 comes to about 999,000. Using the 5 per cent annual
rate of net naturaldecreaseamong the Brazilianslave populationof this period,
cited by Curtin,50on the basis of Curtin's formula and the slave population
figures of I80I and 1850, above, the total number of slaves importedinto Brazil
from I801 to I850 comes to approximately3,700,000. Curtin's estimate of total
Brazilianimport for the wholeperiod of the slave trade is 3,646,800.
It is probablethat the Brazilianimports of this period were not as large as the
figure presently estimated. This will mean that the slave population figure for
I801 ought to be much higher than the one we employed. This puts much
doubt on the accuracy of the figures cited by Curtin in his paper (p. 604).
However, Dr Eltis's recentpaper,based on much wider datathan those employed
by Curtin's 'Brazilian historians', shows a large under-estimate of Brazilian
imports by Curtin for the period studied by Eltis.51Curtin himself confessed
that the estimates of his Brazilianhistorians are less securely based 'than the
calculationsbased on French or English shipping data'.52Curtin's estimates of
the British-carriedtrade have now been shown beyond any reasonabledoubt to
be a substantialunder-estimate,due mainly to the employment of incomplete
data in his computation.And this will alwaysbe the case when incomplete data
form the basis of slave import or export estimate.
Two minor points may be made briefly before we bring the paper to a conclusion. One is that Curtin still insists that the figure of 353,200 slaves he stated
in the Censusas the net slave import for Jamaicain the period, I702-75, on the
basis of JamesFuller'slist, is correct(p. 605). I have no alternativebut to publish
the whole list in Appendix II, below, so that the figures can be added up by the
readersfor themselves. My own calculationsmake the net import for the period
360,712 slaves.
49 Ibid. 20-I.
P. D. Curtin, 'Epidemiology and the Slave Trade', Political Science Quarterly,
LXXXIII(I968), 214. This rate is given by Curtin as applicable to the period I772-I873.
I cited Curtin in my original paper, and do so now, because he is my source for this
information.
51 D. Eltis, 'The Direction and Fluctuation of the Trans-Atlantic Slave Trade I821-43:
A Revision of the I845 Parliamentary Paper', paper presented at the Mathematical Social
Science Board Seminar on the Economics of the Slave Trade, at Colby College, Waterville,
52
Maine, U.S.A., 20-22 Aug. I975.
Curtin, Census, 205.
60
40
AH XVII
624
J. E. INIKORI
The other point is rather interesting. Curtin now accepts that in the Census
he employed, for the British Caribbean estimates, slave population figures taken
from tax rolls (pp. 600-602 and n. 5). Recently, however, before an academic
audience at Colby College, on 21 August 1975, Professor Curtin said he did not use
in the Census any slave population figures taken from tax rolls. I believe he made
that statement then out of genuine ignorance. But he owes an apology to those
scholars who attended the Colby College Conference.
III
In conclusion, it has to be noted that Curtin did a legitimate job in bringing
together in the Census some of the published material on the subject of the slave
trade and slavery. But that praiseworthy exercise is marred by the misleading
assertions which Curtin carelessly made in the book. Not only did he make
misleading assertions about the level of accuracy to be expected from his
estimates, but also, he repeatedly told his readers that the errors in the estimates,
if any, could only be errors of over-estimate rather than under-estimate. I found
these assertions completely unwarranted. This was the occasion for my original
paper. It is interesting to note that contrary to Curtin's assertions in the Census,
the only two works that have attempted global estimates of slave exports and
imports for particular periods since the publication of his book-Anstey,53 for
both established errors of
the period I76I-I8I0;
Eltis,54 for I82I-43-have
under-estimate rather than over-estimate. Serge Daget's discovery55 of a very
large volume of French slave trade in the nineteenth century makes even Eltis's
estimates conservative. My own estimates for the English-carried trade make
Anstey's estimates, again, conservative. My estimates of the English-carried
now stand at 2,307,986, taking no
slave export for the period I750-I807,
account of unrecorded trade, and 2,4I6,9I0, taking into account unrecorded
trade. A different method of estimating the English-carried trade puts the total
for the whole of the eighteenth century, 170o-I807, at 3,699,572.
The main factors which pushed Curtin's estimates in the Census generally
to the low side are his exaggerated view of the year-by-year fluctuation in the
volume of the Atlantic slave trade; his use, unknowingly, of official records
which were either incomplete or systematically understated the volume of the
slave trade; his acceptance of estimates made by other writers on the basis of
similar official records; and his use, again unknowingly, of a formula that has
an inbuilt tendency to under-estimate the volume of the trade, given the historical
conditions.
Curtin has completely misunderstood what I tried to do in my original paper.
Based on that fundamental misunderstanding he has taken the whole issue as a
personal attack on his integrity. Consequently he has chosen to adopt desperate
tactics, appealing to the sentiments of his readers rather than to their reason,
even to the extent of imputing political motives to his critics. This is rather
regrettable.
53 Anstey, The Atlantic
54 Eltis, 'Direction and
Slave Trade, 38.
Fluctuation of the Trans-Atlantic Slave Trade I821-43'.
55 Serge Daget, 'La Repression Britannique sur les Negriers Francais du Trafic Illegal:
Quelques conditions generales ou specifiques', paper presented at the Mathematical
Social Science Board Seminar on the Economics of the Slave Trade, at Colby College,
Waterville, 20-22 Aug. I975.
MEASURING
THE ATLANTIC
SLAVE TRADE
625
I
APPENDIX
Official value of commodity exports from England to the African Coast, 1701-1807
?
Year
1701
1702
133,954
96,052
1703
1704
1705
1706
104,180
86,666
65,105
56,686
1707
92,128
1708
1709
1710
171I
55,994
59,404
68,987
64,277
1712
1713
37,508
111,805
1714
63,417
1715
51,912
1716
1717
1718
97,886
112,450
93,314
1719
66,442
1720
130,351
1721
1722
126,056
I86,556
?
Year
I740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
I757
1758
II0,544
132,691
130,385
219,048
95,093
71,400
117,474
186,400
233,671
I98,439
160,792
214,641
236,063
275,360
235,058
173,671
I88,629
154,497
167,898
22 years: 4,032,974
?
Year
1774
1775
1776
1777
1778
846,525
786,169
470,779
239,218
154,086
1779
159,2I7
1780
195,908
7 years:
2,851,902
1781
1782
1783
1784
1785
1786
1787
1788
1789
312,823
351,735
787,564
523,806
587,197
888,739
727,634
735,340
669,713
1790
929,203
1791
22 years: 1,961,130
1792
1759
1723
138,508
1761
228,460
345,549
325,352
1724
1725
216,368
284,025
1762
273,129
1726
1727
1728
218,705
138,608
I87,404
1729
253,380
1730
260,690
1731
206,103
1763
1764
1765
1766
1767
1768
1769
463,818
464,879
469,034
496,792
558,062
612,392
605,185
1732
1733
1734
1735
1736
204,000
128,788
128,684
130,419
193,154
1760
14 years: 2,688,836
1737
1738
1739
234,I00
277,248
219,874
Sources: 1701-49:
P.R.O.,
1781-1807:
11 years: 4,842,652
1770
1771
1772
1773
571,003
712,539
866,394
662,113
4 years: 2,812,049
P.R.O.,
BT.6/241,
Customs 17/7-29.
fo.
22;
1750-80:
856,083
1,367,919
1793
13 years:
384,588
9,122,344
1794
1795
1796
1797
r798
1799
800o
I801
1802
1803
1804
I805
1806
1807
I4years:
P.R.O.,
749,823
432,852
600,170
800,215
1,115,793
1,339,391
I,024,599
1,044,940
1,145,359
819,327
1,174,669
991,451
1,243,363
701,768
13,83,720
Customs
3/50-80
626
J. E. INIKORl
APPENDIX
II
The number of slaves imported into Jamaica from Africa and the number re-exported,
yearly from 22 September 1702, to 1775
Net Jamaican import, 1702-75 = 360,712 slaves
Year
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
I713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
Slaves
imported
843
2,740
Slaves
re-exported
327
481
Year
1740
1741
221
1742
3,503
3,804
3,358
6,627
1,669
I,o86
897
I,379
1743
I744
1745
2,234
1,275
I,191
1748
1,532
1749
1,903
2,712
1750
4,120
3,662
6,724
4,128
4,378
5,789
2,372
6,361
7,551
6,253
5,120
5,064
3,715
8,469
6,824
6,852
10,297
1746
1747
I751
3,507
1,089
2,872
3,153
1753
1754
1755
2,247
1756
3,161
2,815
1,637
3,263
4,674
3,569
3,388
1757
I752
1758
I759
5,212
I760
1761
7,573
6,480
6,279
10,079
1762
1763
I764
I765
11,703
3,876
5,350
10,499
1,555
986
4,820
10,104
5,222
10,079
I3,552
7,413
4,570
4,851
3,913
8,995
7,695
6,787
5,708
5,288
5,I76
1,666
1772
2,260
1773
4,112
Slaves
imported
5,362
4,255
5,o67
8,926
8,755
3,843
4,703
10,898
10,430
6,858
3,587
4,840
6,I17
7,661
9,551
12,723
II,I66
7,935
3,405
10,213
8,951
1766
10,208
1767
1768
I769
1,647
1774
3,248
5,950
3,575
6,824
4,183
5,278
9,676
I8,448
2,240
1775
9,292
2,070
598
1770
177I
497,726
Slaves
re-exported
495
562
792
1,368
1,331
1,344
1,502
3,378
2,426
2,128
721
713
I,038
902
1,592
598
1,902
943
411
68i
2,368
642
232
1,582
2,639
2,oo6
672
375
485
420
836
671
923
8oo
2,5II
1,629
I37,014
Source: British Museum 524.K.I4, Report of The Lords of Committee of Council Appointed
for the consideration of all matters relating to Trade and Foreign Plantations (1789), part III,
appendix, Jamaica. See also P.R.O., C.O. 137/38, fo. 5.
MEASURING
SLAVE TRADE
THE ATLANTIC
APPENDIX
627
III
An extract from page I39 of L. Peytraud, L'Esclavage aux Antilles Franfais avant 1789
d'apres des documents inedits des Archives Coloniales (Paris, I897):
Voici un releve etabli par une note manuscrite de Moreau de Saint-Mery vers 17801:
Esclaves
Saint-Domingue ..............
Martinique ..................
Guadeloupe ..................
Sainte-Lucie ................
Marie-Galante ..............
Tabago ....................
Cayenne ....................
Les Saintes, Sainte-Marie et la
Desirade ..................
452,000
76,000
90,000
20,000
10,000
Affranchis
25,000
5,0ooo
3,500
,800
I00
15,000
I0,000
300
500
500
200
673,500
36,400
1Arch. Col., F, 134, p. 354. Les chiffres sont tires des journaux et des documents
officiels.