August 27, 1920] 



SCIENCE 



201 



digestive juices, but that all actions of the 

 individual are affected by the particular sur- 

 rounding conditions of such actions. 



That unfortitnate effects result from the 

 failure to appreciate the fact that in dealing 

 with the human organism we are not dealing 

 with isolated elements is a common observa- 

 tion in medical practise. All too frequently 

 an individual, who is clearly in the process of 

 preventable disintegraton, is caused to break 

 down completely because the elemental theory 

 actuates the psychiatrist to pronounce that 

 there is nothing wrong with a person having 

 no apparent organic or functional lesion. The 

 writer wishes to suggest, that at least from a 

 medical standpoint, we have placed too great 

 emphasis upon the chemical factors in the 

 process of human digestion and too little 

 stress upon the psychological factors. 



J. E. EIantor 



University of Chicago 



A SIDEWALK MIRAGE 



To THE Editor of Science: It seems the 

 phenomenon here described must have been 

 noticed by many others, but it caught my 

 attention for the first time about two weeks 

 since, and nowhere have I seen it described. 



On several occasions, lately, I have observed 

 a mirage under the conditions hereafter stated 

 which are those of a tjrpical case. I was 

 walking eastward on a cement sidewalk on a 

 street running nearly east and west, and 

 moving up a moderate grade which joins a 

 nearly level stretch of walk. On reaching a 

 point which brought my eye slightly above 

 the level portion, and at which normally the 

 level stretch would have been seen in its 

 entire length, but much foreshortened, I ob- 

 served instead what appeared to be a stretch 

 of clear dark water covering the entire width 

 of the walk, and brilliantly reflecting moving 

 persons and other objects in sight beyond it. 



The sky was clear, the air cool, the sun 

 high. It was about three o'clock p.m., local 

 time. There was a moderate breeze. The 

 angle of observation was very small, probably 

 not above three degrees. A step or two 

 either east or west, and the water was gone, 



but within the proper limits, the illusion was 

 definite and continuing. The Weather Bu- 

 reau report for the day indicates that ap- 

 proximately 30 feet above the spot where the 

 mirage was observed the air temperature was 

 about 63° F. and the humidity about 63°. 



The resemblance between conditions here 

 described and those which produce the mirage 

 on the plains is obvious. 



F. W. McISTair 



Michigan College op Mines 



SCIENTIFIC BOOKS 



Helmets and Body Armor in Modem Warfare. 



By Bash FORD Dean. New Haven, Tale 



University Press. 



To most of us armor belongs to the roman- 

 tic past. We hardly think of it as a prac- 

 tical, up-to-date accessory of modern warfare. 

 But in a book which has recently appeared, it 

 is clearly demonstrated that armor has still 

 a distinct value. We are of course familiar 

 with the various steel helmets used by all the 

 nations in the Great War, but it is not gen- 

 erally known that all the countries were hard 

 at work experimenting with and developing 

 body armor of every sort for their fighting 

 men. General Pershing recognized its value 

 and in the title page of Dr. Bashford Dean's 

 "Helmets and Body Armor in Modern War- 

 fare " he is quoted as saying that " effort 

 should be continued towards a satisfactory 

 form of body armor." 



Dr. Dean is the foremost authority on 

 armor in this country and curator of arms at 

 the Metrojwlitan Museum of Art. When we 

 entered the war he was placed in charge of 

 the armor problem and his tireless energy and 

 enthusiasm, together with the generous co- 

 operation of the Metropolitan Museum, led to 

 the development of many types of armor for 

 our combat troops. It is unfortunate that 

 too little of this armor was used during the 

 final drive of 1918. 



Dr. Dean views the subject from many 

 angles. The introduction is devoted to the 

 evolution of modern armor from early times 

 and enables one to contrast the old with the 

 new. The medical viewpoint is considered 



