344 



SCIENCE. 



[N. S. Vol. II. No. 37. 



BOLOMETEIC INVESTIGATIONS ; A CORRECTION. 



Prof. Joseph Le Contb has kindly called 

 my attention to an error in the above article. 

 On page 175, 7 lines from the bottom of first 

 column, it should read million instead of thou- 

 sand, and after line 5 insert million, that is, the 

 limits are four hundred million million and 

 seven hundred million million times per second. 

 The error was made in transcribing the original 

 manuscript and was not caught in my proof 

 reading. William Hallock. 



SCIENTIFIC LITERATURE. 

 The Orowth of U. S. Naval Cadets. By Henry 



G. Beyer. (Proceedings of the United States 



Naval Institute, Vol. XXI., No. 2. Whole 



No. 74). 



In this paper Dr. Henry G. Beyer discusses 

 measurements of U. S. Naval Cadets. These 

 measurements form an exceedingly valuable 

 material for the study of gro%vth. The charac- 

 ter of the material may be judged from the fol- 

 lowing remarks of the author : 



' 'It has been the custom at the Naval Academy 

 for the last thirty years or more to make an an- 

 nual physical examination of every cadet in 

 training at that school, and, at the same time, 

 to keep a record of certain anthropometric meas- 

 urements of every cadet undergoing such ex- 

 amination. * * * Up to a few years ago the 

 height standing, perineal height, circumference 

 of chest, waist measure and the lung capacity 

 were the only items recorded. Within recent 

 years the height sitting, span of arms, strength 

 of squeeze, acuteness of vision and hearing have 

 been added to these records ; the number of ob- 

 servations under the first-named items is, conse- 

 quently, much larger than that under the last 

 named. ^ 4,. ^ .x. The cadet who stays the full 

 term of four years at this school leaves on the 

 books the records of five successive examina- 

 tions taken one year apart ; after graduation 

 two years are spent at sea, after which time the 

 cadet returns to the Academy for his final ex- 

 amination, leaving the records of another phys- 

 ical examination. This makes six in all. Since 

 the age for entrance into the Academy is limited 

 to from 15 to 18 years, and taking six years as 

 the time necessary to elapse between the first 

 and last examinations, the period of growth 



covered by these records ranges all the way 

 from 15 to 24 years of age."* 



The most important part of the investigation 

 is the discussion of individual growth which 

 proves beyond a doubt that the assumption 

 which was made by Bowditch and Porter, 

 namely, that on the average individuals of a 

 certain percentile rank retain this I'ank through 

 life does not hold good. Dr. Beyer considers 

 boys of 15 years of age and representing the 

 25th and 75th percentile grades. It appears 

 from the tables given by the author that the av- 

 erage statures of both classes approach more and 

 more the 50th percentile grade. I have comput- 

 ed the rank of these boys from year to year from 

 the statements given by Dr. Beyer, and obtained 

 the result that boys who ranked at 15 years 

 26 fct and 73 fc ranked in the following years : 

 Years 15 16 17 18 19 20 21 



Grade 26 28 26 34 27 38 38 



Grade 73 74 69 69 68 65 — 



It appears that the approach of the lower 

 grade towards the middle is greater than that 

 of the higher grade. In the consideration of 

 weight the approach of the lower grade toward 

 the middle grade appears even stronger, while 

 the higher grade even exceeds the correspond- 

 ing normal grade. It is difficult to understand 

 the reason of this phenomenon. It would seem 

 likely that when we select a certain grade at a 

 certain age, and follow the development of the 

 individuals composing the grade, that the condi- 

 tions of life during the following years are favor- 

 able in some cases, unfavorable in others, but, 

 on the whole, correspond to the average condi- 

 tions. When, therefore, the initial age is re- 

 mote from the adult stage, we should expect a 

 gradual approach to the average. This phe- 

 nomenon is observed in the case of stature, but 

 does not appear clearly in the case of weight. 

 As Dr. Beyer does not give his original observa- 

 tions, it is impossible to judge what may be the 

 cause of this curious fact. 



The same subject is treated in a small but 

 useful table (XVII.), which proves that when a 

 small group of individuals whose statures at 



* In addition to these data -we should like to know 

 the restrictions governing the selection of cadets 

 which are of great importance in interpreting the ob- 

 served distribution of nieiisuremeuts. 



