1888.] 



on Personal Identification and Descripti 



349 



A curve drawn tlirougli their tops gives the upper boundary of the 

 scheme ; the lines themselves are then wiped out, having served their 

 purpose. If the base A B be divided into three equal parts and 

 perpendiculars, C, D ; E, F, be erected at the divisions between them, 

 reaching from the base up to the curve, then the lengths of those 



Fig. 4. 



perpendiculars will be proportionate to the limiting values between 

 the small and the medium group, and between those of the medium 

 and the large group, respectively. The difference between these 

 perpendiculars in the case of stature is about 2 • 3 inches. In other 

 words, the shortest and tallest men in the medium class differ only 

 by that amount. We have next to consider how much ought 

 reasonably to be allowed for error of measurement. Considering 

 that a man differs in height by a full third of an inch between the 

 time of getting up in the morning and lying down at night ; con- 

 sidering also that measures are recorded to the neai'est tenth of an 

 inch at the closest, also the many uncertainties connected with the 

 measurement of stature, it would be rash not to allow for a possible 

 (I do not say " probable ") error of at least ± half an inch. Prolong 

 C D, and note the points upon it at the distance of half an inch above 

 and below D ; draw horizontal lines from those points to meet the 

 curve at d.l, d.2, and from the points of intersection drop perpen- 

 diculars reaching the base at c.l, c.2. A similar figure is drawn at F. 



