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~.--IM_
----JI ~-6([@~~~ :~ ...._(_·__M_ E_ T_R_I_C_S_Y_S_T_ _E_M___l
E _T_E_R
_S
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registering in order units, tens, hundreds, and
thousands of kilowatt-hours.
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The metric system is so simple that it has been
said that a man cast on a desert island with ·a
cubic centimetre measure (two-fifths of an inch
each way) graduated in millimetres could with
it reconstruct all the measures of length,
capacity and weight, and measure with scientific accuracy everything on the island, from the
length of a bee's wing to the height of the
mountains and the area of the island itself.
The fundamental metric unit of length is the
metre, which is a li~tle more than a yard (39·37
inches). Dividing the metre by 10, lOO, and
1,000 gives the smaller units, distinguished by ·
the Latin prefixes deci-, centi-, and milli- ; multiplying by the same numbers gives the larger
units, distinguished by the Greek prefixes
deka-, hekto-, and kilo-, as in th-i s table :
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Mechanism of Gas Meters
The gas meter has two gas-tight chambers,
each having a leather bellows arrangement.
The disks of the bellows are connected in such
a way that when one bellows expands the other
contracts. Gas for the burners is drawn, first
from inside one bellows, then the other. The
valves are so arranged that gas from the mains
is supplied to the chamber surrounding the
bellows which is being emptied. The pressure
in the chamber squeezes gas from the bellows
which the chamber contains into the burners
as needed.
Meanwhile the other bellows is expanding.
This draws in gas from the surrounding chamber,
which has been filled by the previous operation
of the meter. When one bellows is empty the
valves shift and reverse operations. Mechanism
is provided whereby the shifting of the valves
operates the small drive shaft to the cog-wheels
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10
10
10
10
10
10
.
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I
2
.
r
3
'
4
9~
O
~
9
"'
8
8
./
1
.7
5
100
1,0 0 0
10.000
6
0
r "'
'~
6
~
·~
5
I
9~
0
2
2
(~..,.,.
.3
3
'
4
4
~
7
s..YJ
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READING THIS MONTH
4-20
READING LAST MONTH
DIFFERENCE
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5 380 0
5 2 20 0
I 6 0 0
1
5-20
(Showi ng number of cubic feet of
sas used duri n~ current month)
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10
10
10
10
10
10
For each dial put down the lower of the two figures between
which the arrow is pointing (if between 9 and o, read 9), and
subtract from this total the reading on last month's bill.
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of the dials, so that the number of revolutions
indicates the number of times the measure of
gas in the gas-chamber has been used by the
customer, and the scale on the dial shows just
how many lOO's, l,OOO's, and lO,OOO's of cubic
feet of gas have actually passed through.
Scientific men the world
over use the decimal " metric " system for
weights and measures ; and many countries
besides France, in which it originated, have
adopted it for traq.e and commerce and all the
purposes of daily life as well. In fact, the
English-speaking countries are almost the only
progressive countries which have not yet adopted
the metric system for all purposes.
METRIC SYSTEM.
any
=
=
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millilitres (ml.)
centilitres
decilitres
litres
d ekalitres
h ektolitres
1
1
1
1
1
1
=
=
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centilitre (cl. )
decilitre (dl. )
litre (l. )
dekalitre
hektolitre (hl.)
kilolitre
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.The cubic capacity of a litre, it will be seen,
is 1,000 cubic centimetres. The litre and the
hektolitre are the units in thi~ table chiefly
employ~d. Dry and liquid measures are identical in the metric system; but where the metric
system is employed in commerce there is the
same tendency to buy and sell by weight
instead of dry measure.
One millimetre of pure water weighs 1 gram,
the basic metric u:r+it of weight. Multiplied and
divided for larger and smaller units, it gives :
10 milligrams (mg.)
1 centigram ( cg.)
1 decigram ( dg.)
10 centigrams
1 gram (g.)
10 decigrams
-1 dekagram
10 gram!?
1 h ektogram
10 dekagrams
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The word '' meter '' comes from the Greek met1·on,
" measure," from which also comes "metre," applied
to the basic unit of the metric system. (See J\1etrie
System.)
For
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.
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=
centimetre (cm.)
decimetre (dm.)
metre (m.)
dekametre
h ektometre
kilometre (km. )
A hollow cube measuring 10 centimetres on
each edge would hold 1 litre, the basic unit of
capacity in the metric system. It is just about
1! pints. It is divided and multiplied to make
the smaller and larger units, respectively, as is
the metre:
.
.
.
1
1
1
1
1
1
The Basic Unit of Capacity
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WRITE
DATE
HERE
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The units most used in actual measurements
of length are the millimetre (about :l5 inch), the
centimetre (about i- inch) , the metre, and the
kilometre (about! mile 3,280 feet, to be exact) .
In surface measure the most common unit
is the hectare (10,000 square metres), . equal to
2,471 acres.
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HOW TO READ YOUR GAS METER
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mHlimet:res .(mm .)
centimetres
d ecimetres
metres
dekametres
hektometres
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10
10
10
10
h ektograms
kilograms
myriagrams
quintals
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1
1
1
1
----
kilogram (kg.)
myriagram
qwntal (q.)
metric ton
subject not found in its alphabetical place see ii n .t ormation
2386
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