SHORT
COh~iMUNICATIONS
Finally, then, for D > 0,
~-2~-~-~-~ln ~/C+l/D
A
f70
Table 1. z for ordered Cu3Au
~(10) 1-°
gappr(l 0) 12
cm2.dyne-~
cm2.dyne-~
f
(Cx2_D~)+ oG(X)dx.
(5)
Nilsson (1957) has suggested a simple formula for
derived by t a k i n g the m e a n values of each of the terms
in the n u m e r a t o r and d e n o m i n a t o r of e q u a t i o n (2)
separately:
Ibl(Cll +C12) +C44(2Cll +C44)
Zappr. =i~blb21
2 +~bl(Cil + C12)C4~ + CllC]a .
(6)
Table 1 shows a comparison b e t w e e n the values of
~appr a n d ~ obtained by numerical integration of e q u a t i o n
(5) at intervals of 0.05 in x. The elastic constants used
were those given by Flinn, McManus & R a y n e (1960)
for well ordered Cu3Au. Of course, for other t h a n monoatomic systems, alloys (such as Cu3Au) or c o m p o u n d s
of atoms of different masses, this correction does n o t
t a k e into account t h e more complex n a t u r e of t h e
vibrational spectra. A t the present t i m e though, this is
n o t possible a n d t h e t y p e of correction discussed here
is all t h a t is presently feasible. The comparison of t h e
two calculations in Table 1 shows the t y p e of error
t h a t m i g h t occur, even w i t h a m o n o a t o m i c crystal.
I t is clear t h a t the exact formula, e q u a t i o n (5), should
be used for the case D > 0, D/C < 1. B y contrast, Nilsson
1615
T
77 oK
298
(equation (5))
3.12
3"91
(equation ( 6 ) )
4"32
4.62
Error (%)
438"4
+ 18.2
(1957) showed t h a t for KC1 a n d NaC1, for which D <0,
t h e a g r e e m e n t was w i t h i n a few percent.
The a u t h o r is i n d e b t e d to Prof. I. Stakgold who
suggested t h e m a t h e m a t i c a l t e c h n i q u e for evaluating
e q u a t i o n (4) and to Mr P. Gehlen who wrote t h e program
for the numerical integration. H e further wishes to
express his appreciation to Prof. J. B. Cohen for his
e n c o u r a g e m e n t in this work.
References
CttIPMAI~, D. n . & BATTERMAN, B. W. (1963). J. Appl.
Phys. 34, 912.
C]ZIPMA~, D. R. & PASl~IN, A. (1959). J. Appl. Phys.
30, 1992, 1998.
FLINlV, P. A., McMANuS, G. M. & I=~AYNE,J. A. (1960).
Phys. Chem. Sol. 15, 189.
NILSSON, N. (1957). Ark. Phys. 12, 247.
Notes and N e w s
Announcements and other items of crystallographic interest will be published under this heading at the discretion of the
Editorial Board. The notes (in duplicate) should be sent to the General Secretary of the International Union of Crystallography (D. W. Smits, Rekencentrum der Rijksuniversiteit, Grote Appelstraat 11, Groningen, The Netherlands).
Publication of an item in a particular issue cannot be guaranteed unless the draft is received 8 weeks before
the date of publication.
Rel~inald William James, 1891-1964
Sir Lawrence
Bragg writes: R. W. James, who died in
Cape Town on 7 July 1964, was one of the pioneers of
X-ray crystallography. James graduated with first-class
honours in Physics at Cambridge in 1912 and for two years
carried out research in the Cavendish. In 1914 he was
invited by Sir Ernest Shackleton to join his antarctic
expedition as physicist, and when the Endurance
was
crushed by the ice and the party returned to England
after its rescue, James joined the experimental Sound
:Ranging Section for locating enemy
guns which had
been established in Belgium under W. L. Bragg. Their
close association in their war work naturally led to
James joining Bragg at Manchester in 1919 when the
latter was appointed Professor of Physics there. It was
in this way that James entered the field of research in
which he was to work for the rest of his life. He collaborated with Bragg and Bosanquet
in the series of
'B.J.B.' papers from 1921 onwards which established
the quantitative
measurement
of X-ray
diffraction.
:Darwin had formulated
the theory for perfect and
imperfect crystals, and the intensive study of diffraction
of sodium chloride as a s t a n d a r d 'mosaic' crystal, in
particular the comparison of the i n t e g r a t e d reflexion
with the intensity of the incident beam, established t h e
use of absolute values of F(hkl) in X - r a y crystallography.
Two d e v e l o p m e n t s s t e m m e d from this work. On t h e one
h a n d J a m e s a n d his colleagues m a d e a profound s t u d y
of atomic scattering factors a n d the influence of t h e r m a l
m o v e m e n t s (Debye effect) and the q u a n t i t a t i v e measurem e n t s culminated in the well k n o w n paper by James,
H a r t r e e & Waller in which the zero-point energy was
directly measured. On the other hand, absolute F values
provided crystallographers with a means by which far
more complex crystals could be tackled. J a m e s a n d
W o o d were responsible for one of the earliest of these
investigations, the structure of barium sulphate, which
has eleven parameters. This m a r k e d a great step forward
at a t i m e w h e n it was widely d o u b t e d w h e t h e r crystals
with more t h a n two parameters could be analysed with
significant results. J a m e s ' s work at Manchester centred
r o u n d t h e t h e o r y of X - r a y diffraction a n d accurate
q u a n t i t a t i v e m e a s u r e m e n t . His book The Optical Principles of the Diffraction of X-Rays, published in 1948,
has a world-wide recognition as the s t a n d a r d t e x t book
on the subject.
I n 1937 J a m e s was a p p o i n t e d Professor of Physics
1616
NOTES
AND NEWS
in t h e U n i v e r s i t y of Cape Town. H e built up an active
research school; the m a i n interest of his pupils (one of
t h e m is A. Klug, well k n o w n for his work on virus) lay
in t h e field of complex organic compounds.
J a m e s was a fine lecturer and a polished writer.
Towards the end of his time at Cape Town he became
involved in a d m i n i s t r a t i v e work, a n d for a year served
as Acting Principal a n d Vice Chancellor. Although teachLug a n d research were always his m a i n interests, he h a d
a high r e p u t a t i o n amongst his colleagues for his sane
j u d g e m e n t in university affairs. He was elected a Fellow
of t h e :Royal Society in 1955.
Chromatic focusing, of X-ray diffraction lines
Cameras w i t h chromatic focusing are useful in certain
studies of X - r a y line broadening. The m e t h o d has been
developed particularly by Professor J a n ~erm~k, who
can supply descriptions of the experimental details a n d
n o m o g r a m s for finding o p t i m u m focusing conditions on
request. His address is 13stay F y z i k y Pevn:~ch Latek,
P r a h a 6, Cukrovarnick~ 10, Czechoslovakia.
International Union of Crystallography
C o m m i s s i o n on Crystallo~,raphic Apparatus
Sin~,le-crystal Intensity Project
Currently there is considerable a c t i v i t y b o t h in the
collection of extensive single-crystal X - r a y d a t a a n d in
t h e m e t h o d s of ~ttaining high accuracy in the measurem e n t of interLsities of individual reflexions. This interest
led to the Open Sessions of the Commission at the Sixth
I n t e r n a t i o n a l Congress of the U n i o n at Rome, Sept e m b e r 1963, on ' A u t o m a t i c Single-Crystal Diffractometers for X-rays a n d l~eutrons'. The Open Sessions did
not, however, t r e a t questions of accuracy in the measurem e n t of intensity, which is of considerable importance
for a v a r i e t y of reasons, such as the d e t e r m i n a t i o n of
precise atomic parameters, of the detail of atomic and
molecular vibrations and of the location of electron
redistribution arising from bonding. I t would therefore
be useful to arrive at a valid measure of the accuracy
which can be expected from counter measurements.
This cannot be achieved completely from m e a s u r e m e n t s
on a single assembly of a n y one t y p e which would yield
only a measure of internal accuracy. Assessment of
m e a s u r e m e n t s on a s t a n d a r d c o m p o u n d on a v a r i e t y of
single-crystal diffractometers preferably of different
designs will be required. I n this way, variation directly
a t t r i b u t a b l e to basic design m a y be assessed. To carry
out such a proposal effectively, it will be necessary to
gain the cooperation a n d assistance of m a n y crystallographers t h r o u g h o u t the world.
To contribute to t h e clarification of this situation,
it is proposed t h a t t h e Commission on Crystallographic
Apparatus organize such a project as part of its activities
during 1963-66. Plans h a v e been completed as to t h e
simple procedure to be followed.
I t is i n t e n d e d t h a t the participants will carry out t h e
m e a s u r e m e n t s by the m e t h o d normally followed in their
laboratory. Only the s t a n d a r d material {organic) and the
range of reflexions selected for m e a s u r e m e n t will be
specified.
Dr S. C. A b r a h a m s (Bell Telephone Laboratories Inc.,
Murray Hill, New Jersey 07971, U.S.A.) is t h e Commission m e m b e r responsible for this project w i t h t h e
assistance of Dr D. C. Phillips and Professors Y. Saito
a n d M. M. U m a n s k y . Those desirous of participating in
the project should contact Dr A b r a h a m s for a supply
of the s t a n d a r d material and copies of the questionnaire
a n d d a t a sheets.
W'e would be grateful for the cooperation of a n y
crystallographer equipped to carry out t h e m e a s u r e m e n t s
with a hand-set or a u t o m a t i c diffractometer. The greater
the number, the more significant will be the conclusions
of the project. Cooperation in the project offers t h e
o p p o r t u n i t y to gain an objective assessment of yore" own
assembly.
I t is i n t e n d e d t h a t the numerical t r e a t m e n t of the d a t a
will be h a n d l e d by Dr ~V. C. H a m i l t o n .
Book Reviews
Works intended for notice in this column should be sent direct to the Editor (A, J. C. Wilson, Department of Physics, University College, Cathays Park, Cardiff, Great Britain). As far as practicable books will be reviewed in a country different
frown that of publication.
Systematische Klassification der Massengesteine. Par F. RO~ER. Wien: Springer-Verlag,
1963.
L ' a u t e u r nous pr@sente une classification mingralogique
quantitative modale des roches ign@es. I1 n ' a pas employ6
le t e r m e ' E r u p t i v g e s t e i n e ' afin d'6viter route id@e g@n@tique, et utilise le t e r m e 'Massengesteine' afin de ne pas
laisser de c6t@ d'@ventuelles m i g m a t i t e s n o n gneissiques.
I1 essaye de concilier la classification de J o h a n n s e n ,
trop rigide, et la n o m e n c l a t u r e de Tr6ger, t o u t en se
r~clamant surtout de Rosenbusch.
Dans la premi@re part/e, nous trouvons u n expos@
critique des principes de classification, et nous aboutissons/~ la d@finition de 39 families associ@es en 7 groupes:
roches
roches
roehes
roches
roches
roches
roches
quartziques, 1 famille;
quartzo-mafiques, 1 famille;
quartzo-feldspathiques, 5 familles;
feldspathiques, 15 families;
feldspathiques et feldspathoidiques, 5 familles ;
feldspatho~diques, 4 famiIles;
mafiques, 8 families.
Chacun de ces groupes se situe g r a p h i q u e m e n t dans