







































Marcu 31, 1923] 
brother, Lt.-Col. M. M. Bidder, pointed out to me, 
every annual class in the local school of engineers 
would, in its turn, verify the meridian line under the 
supervision of their instructors; yet the second 
pyramid has the same orientation (5}’ west of north) 
as the core-plane of the first pyramid. 
_ There are five meridians deduced by Petrie (p. 41) 
from his measurements. Of these the lowest an 
highest values occur in the Great Pyramid, being 
—3' 43°46" for the casing sides and -5’ 49’+7” for 
the passage. The four of them representing the Great 
Pyramid core and passage, and the Second Pyramid 
casing and passage, are all covered by the value 
—5' 33°+17”. Petrie’s conclusion (p. 11) is ‘ that 
e original base was probably more accurate than 
0-65 inch in length and 12” in angle.” 
GrEorGE P. BIDDER. 
Cambridge, February 26. 

_ THE undoubted trend of the pyramids at 4600 B.c. 
vas about 5’ west of the present pole. Each of the 
Jata was probably set out afresh from polar observa- 
ion, as that would be easier than transfer by measure- 
nt. The accuracy of work there to 12” of angle is in 
eeping with the accuracy of later work, as of granite 
anes 20 square feet in area with only inch/160 
rror at 3300 B.c., or of weights in eighth century 
.D. with variations all within grain/200. The cause 
of a change of axis of about 5” per century might be 
lue to ocean currents or to earth deformation. 
qs W. M. F. PETRIE. 

Science and Armaments. 
Dr. Frencn’s reply (Nature, February 10) to 
hy letter in the issue of January 20 does not touch 
on the essential idea which I desired to express. 
did not raise the question of the dispensability or 
ndispensability of armaments at the present moment : 
. question on which a great deal might be said, but 
which, I think, is somewhat outside the province 
f Nature. The very columns of this journal are, 
pwever, a witness to a very real international 
rotherhood between men of all lands who find a 
ommon interest in the study of natural science and 
n its ceaseless warfare for the knowledge and control 
f material things for the common good of humanity. 
Taking the wider view, how can it be a consolation 
hat, under the urge of apparent national expediency, 
ven should be spending their time in devising new 
nethods of warfare by the application of that know- 
edge and training which should be a blessing to 
ankind instead of a curse ? The new weapon used 
gainst A by B is to-morrow directed by A against 
. Moreover, these methods, the scientific cleverness 
ind interest of which often provide a poor mask for 
gely against those for whom we now profess friend- 
ip. Such a condition may be difficult to avoid, 
ut the great danger is that we should treat it as 
atural and inevitable, and grow insensible to the 
a Se of these things. Have we forgotten the 
fe) 
ir All valiant dust that builds on dust ” ? 
In the time of Davy it seems clear that science was 
espected as a thing apart from war, and we are led 
fo inquire the reason for the change. Has it not 
geen the willingness of inventors to exploit their 
cnowledge, and to allow themselves to be exploited 
men who cared less than nothing for science and 
l that it really stands for? There was small 
patriotism in many transactions that might be 
ecalled, for things were sold to the highest bidder. 
NO. 2787, VOL. 111] 
heir brutality, are directed, not against barbarism, but. 
NATURE 
ES ee ee ee ee ee et ee a ee a 
429 
My first letter was, in brief, a plea that we should 
treat our science as something rare and precious, 
belonging not to ourselves only but also to all nations. 
Whatever burdensome and unpleasant tasks it may 
fall to our national lot to perform, we shall not face 
them the less effectively because we keep some of 
our most cherished possessions free from the dust 
of conflict. Hence my comment on the proposed 
action at the Science Museum. L. C. Martin. 
Royal College of Science, 
South Kensington, S.W.7. 


Hafnium and Titanium. 
REFERRING to Sir Edward Thorpe’s interesting 
letter on this subject in Nature of February 24, I 
would point out that the Cornish village of ‘‘ Manac- 
can ’’ is in the parish of Manaccan, which adjoins the 
parish of St. Keverne. There is an error also in the 
spelling. ‘‘ Menaccan ’’ should be Manaccan, and so 
with the stream at ‘“ Lenarth,”’ it should be Lanarth. 
Presumably, therefore, the Cornish mineral should 
have been called Manaccanite and not Menaccanite, 
and the “ new element ’”’ from it should have been 
termed “ manachin ”’ and not “‘ menachin.”’ 
Witson L. Fox. 
Falmouth, February 26. 

The Cause of Anticyclones. 
In a letter to Nature of December 23 (vol. 110, 
p. 845) Mr. W. H. Dines has raised certain questions 
connected with the cause of anticyclones. he chief 
observational facts to be explained are the features 
peculiar to most high pressures, namely, the warm 
troposphere, the high and cold stratosphere. But 
not all anticyclones are warm even from a height of 
3 km. up to 8 km. Some are cold to considerable 
heights. The gradual rise of the coefficient of cor- 
relation between pressure and temperature at the 
same level as one proceeds from o to 4 km., and the 
comparative uniformity of the coefficient from 4 to 
8 km., is in itself strong evidence that in our latitudes 
these first 4 km. are the theatre of changes of air 
more and more frequent as the surface is approached, 
and that in the regions above 4 km. the air is nearly 
always of one sort as regards its origin. Again, with 
regard to persistence, Hanslik pointed out that only 
the ‘‘ warm” anticyclones are steady and slow 
moving; the ‘cold’ ones move quickly. Further 
facts to be taken into account are, that the conception 
of an anticyclone as a region of great vertical stability 
and of fine bright weather appears to be correct as a 
tule only for the ‘‘ warm ” anticyclone. In the other 
type anything short of violent weather conditions 
may be experienced. 
I have recently (Q. J. Roy. Met. Soc., January 1923) 
put forward some evidence in support of the view that 
the explanation of the temperature peculiarities of 
the high- and low-pressure systems of our latitudes is, 
to a large extent, contained in the Bjerknes theory 
of their origin. In particular, when a pocket is made 
in the polar front by the southward rush of a great 
patch of polar air and when the pocket is afterwards 
closed behind this patch by the equatorial current 
from the south-west, the result is the formation of an 
anticyclone with closed isobars. From an examina- 
tion of a more or less continuous series of upper-air 
observations I endeavoured to show that in such cases 
the change in barometric pressure at a given spot in 
the British Isles was indeed brought about by the 
fact that a thickness 4 +6h of polar air had replaced 
a thickness / of the equatorial current, and that the 
