362 
NATURE 
[Marcu 17, 1923 

Ir is true that progress was made in certain direc- 
tions during the ‘‘ millenary period of stagnation,” 
for example, the improvements in mathematics due 
to the Arabs. Yet the main fact in the re-birth of 
science in the sixteenth century is the discovery of 
the work of the Greeks, especially in geometry, 
astronomy, and geography. Descartes goes back to 
Pappus, Copernicus to Aristarchus, Toscanelli to 
Ptolemy. There is no question that in the general 
spirit with which the medieval mind regarded Nature 
there was retrogression, and that the Greek mind did 
come to life again at the Renascence, partly in its 
broader quality of rational inquiry, partly in the 
actual works of Greek thinkers. 
F. S. Marvin. 
German Book Prices. 
In reference to Prof. Browning’s letter in NATURE 
of December 23 (vol. 110, p. 845), I should like to 
point out an added difficulty in India and Burma. 
Not only are exorbitant prices charged for German 
books, but to the majority of our students such books 
are useless owing to their ignorance of the language. 
The Indian or Burmese student already has to learn 
English in order to study chemistry, and to ask him to 
learn German as well is too great a handicap and 
should be unnecessary. 
The appearance of certain recent works on inorganic 
chemistry shows that British chemists are capable of 
compiling exhaustive treatises, and a dictionary of 
organic chemistry in English would be invaluable. 
The Society of Dyers and Colourists is preparing a 
colour index, and the combined strength of the 
Chemical Society and Institute of Chemistry should 
be able to produce a work on organic chemistry which 
would enable Indian or Burmese students to carry 
out research in organic chemistry without constant 
reference to German works. 
D. H. PEacock. 
University College, Rangoon, 
February 2. 

Single Crystals of Aluminium and other Metals. 
Tue brilliant account given by Mr. G. I. Taylor 
at the Royal Society (February 22) of the deforma- 
tion of single crystals of aluminium leads me to 
direct attention to work done in this laboratory ten 
years ago by Mr. B. B. Baker and Dr. E. N. da C. 
Andrade. Mr. Baker showed that sodium and also 
potassium cylinders when stretched contracted later- 
ally so as to lead to an approximately elliptical section, 
and when they broke they did so at a chisel edge. 
The surfaces are marked with a double set of slip 
lines. A photograph of the appearance is shown in 
the Proceedings of the Physical Society of London 
for 1913. 
Dr. Andrade, who was experimenting at the same 
time on the traction of metals, showed that similar 
results were obtainable with tin and lead, and also 
with frozen mercury (Phil. Mag. 1914). He con- 
cludes that they are due to large uniform crystals of 
a size comparable with the diameter of the rod. 
From the regularity of behaviour over a length of 
several centimetres it may be concluded that both 
were dealing with single crystals several centimetres 
long in the case of each of these materials—at any 
rate in the same sense as that in which the crystals 
of aluminium are spoken of as being single. 
The crystals of sodium are still in my possession, 
having been carefully preserved in anhydrous paraffin. 
They show the characteristics, even the fine surface 
NO. 2785, VOL. 111] 

markings, practically as well as when they were 
drawn. ALFRED W. PorTER. 
Physical Laboratory, University College, 
London, February 26. 

Paradoxical Rainfall’ Data. 
Ar Blue Hill careful measurements of rainfall have 
been made for thirty-seven years. There is no break 
in the record and the amounts are checked by more 
than one gauge. Data for the entire period 1886— 
1922 are given in Blue Hill Meteorological Observa- 
tions. The average monthly values are : 
January tor'imm. | July 1o4'I mm, 
February TOL” 5, August too:8 ,, 
March . IT69'2 5) September . 103:1 ,, 
April . F ro Yh dane October 9674 ,, 
May . ‘ O4°0) hy; November . OFT Ie 
June . .- VSOrsiees December . 97°9 ,, 
Wear iar 1185-7 mm. : 
Month 98-8 mm. 
The driest month is June and the wettest is March. 
Yet the driest month in the whole period was March 
1915, when the total rainfall was only 1mm. What is 
equally remarkable, the wettest month was June 1922, 
when 274 mm. fell. It is difficult to explain these 
rainfalls on any theory of probability. The June rain- 
fall was not due to abnormally heavy showers. , 
ALEXANDER M‘ADIE. 
Harvard University, 
Blue Hill Observatory, 
Readville, Mass., February 19. 

Atmospherics. 
Many who have “ listened in’’ must have been 
much interested by the peculiar sounds the telephone 
generally emits, in addition to those produced by 
the waves from the broadcasting station. Although 
atmospherics are produced by the electric discharges 
during thunderstorms, many would appear to have 
a very different origin. ; 
In the discussion of a paper on “‘ The Study of Radio- 
telegraphic Atmospherics in Relation to Meteorology,” 
by C. J. P. Cave and R. A. Watson Watt (Journal of 
Meteorological Society, January 1923, pp. 35-42), Mr. - 
L. F. Richardson asked Mr. Watson Watt “ if he could 
explain the origin of the peculiar atmospherics which 
were experienced at Eskdalemuir on the telephone, 
which was connected with an overhead wire in a 
lonely valley. In addition to the ordinary clicks 
there was a ‘ swishing’ sound. The frequency of the 
vibration diminished as the swish went on. This 
property was characteristic of the sound of a shell 
passing high overhead. Mr. Richardson had the idea, 
perhaps a mad one, that the swish might be pro- 
duced by a meteorite.” 
Many of the atmospherics I have heard have had 
this character, and it may be suggested that the idea 
that they are produced by very small meteorites is 
not quite such a mad view as would at first appear. 
In the higher atmosphere, there may be a very 
considerable electric potential gradient, and if a 
meteorite, entering it, ionised a path in it, an electric 
discharge might occur along this ionised path suffi- 
ciently strong to give off electric waves. There is 
indeed reason to suppose that the direction from which 
the waves come is influenced by variations in the 
sun’s position (R. A. Watson Watt, Proc. Roy. Soc., 
vol. 102, 1923, p. 460). R. M. DEELEY. 
Tintagil, Kew Gardens Road, 
Kew, Surrey, February 17. 
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