540 



NATURE 



[December 22, 1921 



War Work of the Bureau of Standards, U.S.A.^ 



THE value of science to the belligerent coun- 

 tries was proved over and over again during 

 the war — in the United States no less than in 

 other countries. The United States, however, 

 had the advantage over other countries in this 

 as in other matters, that, before it joined in 

 the fighting, many lessons had been learned or, 

 at least, were in course of being learned, and 

 of these by no means the least was the fact that 

 scientific workers could render enormous service 

 to the combatant forces. We find, therefore, 

 that, from the very moment of America's entry 

 into the war, the services of the Bureau of Stan- 

 dards were made use of in connection with the 

 many problems which arose. The volume before us 

 is a record of some of these activities, although, 

 as is pointed out, some of the most interesting 

 and important of the investigations carried out 

 cannot be described owing to military or other 

 reasons. Moreover, at the Bureau, as at our 

 National Physical Laboratory, a great deal oi 

 the assistance rendered took the form of oral 

 advice and consultations, the value of which can- 

 not be estimated, and most of which was not 

 of a nature to become part of the permanent 

 records. In spite of these facts, so much work 

 was carried out that the present volume is, 

 perforce, little more than a series of brief 

 abstracts of the many investigations undertaken, 

 and it is possible in a review to pick out only a 

 few of the more interesting of these and to refer 

 briefly to them. 



It is only natural that aeronautics should 

 occupy a prominent place in the activities of the 

 Bureau, and the report opens with a description 

 of the work accomplished on aeronautical instru- 

 ments. Many were designed at the Bureau, 

 where provision was made to give thorough 

 laboratory tests to 4 per cent, of the total pro- 

 duction of the country. These tests included 

 experiments carried out in temperature chambers 

 and on vibration stands, so that the instruments 

 might be subjected to the same conditions as 

 would be encountered in actual use. 



Of very great interest is the "altitude 

 laboratory." This consists of a concrete 

 chamber with walls capable of withstanding a con- 

 siderable pressure from without. Within this 

 chamber the engine under test is mounted and 

 tested under varying conditions of temperature 

 and pressure, it being possible to reduce the latter 

 to as low as one-third of an atmosphere — corre- 

 sponding to an altitude of 35,000 ft. 



Exhaustive tests on ignition systems for aero- 

 plane engines were also carried out, the majority 

 on the sparking-plugs — or ■ spark-plugs, as the 

 Americans term them. The conditions to which 

 these plugs are subjected in aero-engines are much 

 more severe than in ordinary motor-car practice. 

 The pressure inside the cylinders may amount to 



1 "War Work of the Bureau of Standards.' 

 Government Printing Office.) 70 cents. 



NO. 2721, VOL. IO8I 



Pp. 2^9. (Washington : 



600 lb. per square inch, and during operation the 

 sparking-plug is exposed alternately to a blast of 

 air which may be at a temperature well below zero, 

 and to a flame of burning petrol, the temperature 

 of which is estimated at 2500° C. As a result oi 

 research, several porcelains have been obtained, 

 which have high electrical resistance and mechan- 

 ical strength while hot, and are capable of with- 

 standing sudden temperature changes ; they have 

 been largely used in the manufacture of sparking- 

 plugs in the States. In addition to the work on 

 the insulating material of the plugs, brittleness 

 occurring in nickel electrodes has been investi- 

 gated, and cements for fixing the electrode in the 

 insulator have been studied. 



A delightfully simple form of gauge foi 

 measuring the tension of aeroplane wires was de- 

 signed at the Bureau. The wire is supported on 

 two pins at a known distance apart, and loaded, 

 by means of hand levers, at the middle of the 

 span thus formed. The load is measured b> 

 means of one Ames dial, and the deflection of the 

 wire by another. The dials are calibrated so 

 that it is possible to read off the tension directly 

 when the wire is deflected 01 in. 



Reference must also be made to the work on 

 dopes for aeroplane fabrics. These may be divided 

 into two classes, cellulose nitrate dopes and cellu- 

 lose acetate dopes. The former are highly in- 

 flammable, and therefore undesirable. Before the 

 war America obtained all her cellulose acetate 

 from the Bayer Company of Germany, and 

 it was not until after seven months of war that 

 provision was made for securing an adequate 

 supply of raw material. In the meantime, the 

 United States had been reduced to such devices as 

 obtaining cuttings and scraps of kinema films in 

 order to manufacture sufficient quantities of dope. 



Leaving the aeronautical side of the report, and 

 turning to the section headed " Gauges " (or 

 rather "Gages"), one is impressed with the small 

 amount of work done at the Bureau compared with 

 what was done at the National Physical Labora- 

 tory. It appears that the total number of gauges 

 tested at the Bureau and its branch laboratories 

 was 60,000. This is about the average number 

 tested in two months between 191 5 and 191 8 at 

 the National Physical Laboratory, and about the 

 average in six weeks during 1917-18. 



Very interesting reading is furnished by the sec- 

 tion on invisible signalling. In this connection a 

 number of experiments were made, using both 

 ultra-violet and infra-red radiations. It was found 

 that the former were liable to fail owing to a 

 fluorescence which was produced in the eye of the 

 enemy observer — particularly if he were young. 

 Infra-red rays, on the other hand, gave more 

 promising results, but, as no methods are known 

 for detecting them unless one is in the direct 

 line of " sight," it is a moot question whether the 

 method should be developed further. 



It may seem a far cry from the study of ultra- 



