April 22, 1920] 



NATURE 



2S7 



optimum temperature for the breeding of Calandra 

 is about 82° F., but somewhat higher for Rhizo- 

 pertha. C oryzae may increase 700-fold in 

 sixteen weeks, which makes it a more dangerous 

 pest than granaria, which has a slower rate of 

 multiplication. On the other hand, adults of the 

 latter species were found to survive the winter in 

 this country at ordinary room temperature, 

 whereas nearly all those of oryzae were killed off. 

 Rhizopertha succumbs after three minutes' 

 exposure at about 146° F., while i20°-i30°F. 

 is the lethal temperature for both species of 

 Calandra. 



As the consequence of information accumulated 

 in the laboratory, tests along commercial lines 

 need to be carried out in order to ascertain the 



practicability or otherwise of the knowledge thus 

 obtained. We strongly urge that large-scale 

 tests should be inaugurated with as little delay 

 as possible. If such tests confirm the conclusion 

 that the most satisfactory method for the storage 

 of grain in bulk, over lengthy periods, is in air- 

 tight silos or granaries, the Grain Pests Com- 

 mittee is to be congratulated upon a notable 

 achievement. The construction of such receptacles 

 would involve a high initial cost, but probably 

 not excessive when the annual loss from weeviling 

 is recounted. As the authors point out, by such 

 ■a method of storage we should be provided with 

 a means of maintaining a reserve of cereals in 

 the event of war or crop failure, and, we may 

 add. of economic or financial difficulties. 



Some Applications of Physics to War Problems. 



T X an address to the Physics Section of the 

 -■- American Association for the Advancement of 

 Science, delivered at the St. Louis meeting in 

 December last and published in Science for 

 March 5, Prof. Gordon F. Hull describes the work 

 done by a number of American mathematicians and 

 physicists in elucidating the various problems that 

 arose during the war in connection with long- 

 range and anti-aircraft gunnery. It may be of 

 interest, therefore, to record the efforts of a 

 number of British men of science, made at a much 

 earlier date during the war, on which (and on 

 the work of the French) the developments of 

 American scientific gunnery as described by Prof. 

 Hull were largely based. 



Up to the spring of 191 6 the developments oif 

 British ballistic science had come largely through 

 the Ordnance Committee at Woolwich, which dur- 

 ing the war was fortunate in having an officer of 

 considerable mathematical attainments as head of 

 the ballistic office. The mass of work, however, 

 and the extraordinary variety and difficulty of the 

 problems that arose, especially in connection with 

 the new science of anti-aircraft gunnery, made it 

 necessary for the Ordnance Committee to seek help 

 from outside ; and from 1916 onwards the investi- 

 gation of problems in " external ballistics " de- 

 volved largely on the Anti-aircraft Experimental 

 Section of the Munitions Inventions Department. 

 The A..A.E.S., as it was called, consisted of a 

 number of mathematicians and other men of 

 science, mainly fellows and scholars of Cambridge 

 colleges, some from the Patent Office, one from 

 Oxford, and three fellows of the Royal Society^ — 

 some in military, some in naval, and some in 

 civilian clothes. 



The work of this group was undertaken at 

 H.M.S. Excellent, Portsmouth, at Rochford Aero- 

 drome, at the National Physical Laboratory, at 

 University College, London, and at a variety of 

 other plflces. It consisted largely of trials with 

 anti-aircraft guns, shells, and fuses, recording the 

 NO. 2634, VOL. 105] 



positions of shell-bursts at heights up to 33,000 ft., 

 observing and calculating the effects of winds and 

 of pressure and temperature abnormalities, develop- 

 i ing the mathematical theory of ballistic calcula- 

 tions, and investigating the behaviour or the causes 

 of failure and irregularity of fuses. In addition to 

 this, work of considerable mathematical and physi- 

 ! cal interest was done, some of which will be pub- 

 lished, on the general dynamics of shell flight 

 (such problems as the stability of shells, the effects 

 I of rotation of the earth, "drift," the "twisted 

 I trajectory of the shot," etc.), and on the 

 t pressure distribution on the head of a shell 

 ! in flight. The solution of some of these 

 ! problems, undertaken originally in connection 

 with anti-aircraft gunnery, had, in the end, 

 i a considerable bearing upon the theory of gunnery 

 j in general. 



The A.A.E.S., in addition to its main work in 

 investigating the problems of gunnery, did a large 

 amount of routine computing of range tables in 

 conjunction with the staff of the Galton Labora- 

 i tory, and performed a number of interesting and 

 important trials on time-fuses in co-operation with 

 the Engineering Department of University College, 

 London. It carried out far-reaching experiments 

 ' on the use of sound-locators for the detection of air- 

 craft, and in conjunction with the R.E. and the 

 Air Force on the co-operation between such sound- 

 locators and searchlights ; the military equipment 

 and methods finally adopted weie based directly 

 on these experiments. It tested both the theory 

 and the use of a number of instruments required 

 for anti-aircraft work, such, for example, as range- 

 finders, height-finders, and "predictors " (instru- 

 ments for predicting the "future position " of the 

 target at the moment the shell bursts) ; and finally 

 it had what was known familiarly as a " travelling 

 circus," which moved about in Great Britain and 

 France recording the results of practice anti-air- 

 craft shoots, and investigating the performance of 

 guns and instruments. 



