ANTHROPOMETRY 149 



photographs and measurements, the head can be modelled almost to 

 perfection. 



Casts of the body should never be undertaken except by one well 

 practised in the art, for the operation is not without danger to the 

 subject. Casts of the lower part of the trunk and the limbs need 

 experienced hands. The skin must in all instances be well oiled and 

 the part to be cast must not be deformed by wrong position or pressure. 

 A provision for the removal of the cast in sections is a necessity and 

 is usually done by including in the first layer of plaster, along the line 

 of intended separation, a linen thread and by cutting the cast with 

 this as it begins to harden. The preparation" of the plaster and other 

 details are practically the same as in facial casting. 



In packing casts, pad well and tightly with very dry hay or other 

 suitable substance, and use only smaller boxes or barrels. In especially 

 important cases, and where the casts are to be transported a great 

 distance, individual little boxes for each cast, a number of which is 

 then packed in a larger case, are of great advantage. 



ANTHROPOMETRIC INDICES. 



Under the term ' index ' in anthropometry is understood the percental 

 relation of two measurements. It is habitual to use the smaller 

 measurement as the dividend and the larger as the divisor, so that 

 the index is usually less than 100. 



The index is the simplest expression of the geometric relation of two 

 dimensions and as such is of much utility for the prompt conveyance 

 of a notion as to the shape or relative size of parts. The index in 

 general is also more permanent than the absolute dimensions of the 

 parts, and therefore more valuable for group comparisons. 



Due to their usefulness and stability, the indices in anthropometry 

 have almost from the beginning assumed a great favor as well as 

 importance. For the same reasons also they have become greatly 

 multiplied, and their value particularly that of the cephalic index 

 has been sometimes overrated. No index, it is plain, can have more 

 stability than the physiological and mechanical conditions that control 

 the relation of the parts concerned; and as these conditions are not 

 immutable, so the indices are subject to change. 



As in a large majority of cases the correlation of measurements is 

 self-evident, there is a general agreement among workers as to the 

 constituents of the indices; but in the course of time there have 

 developed considerable differences of opinion as to the grouping of the 

 indices and in the nomenclature of the resulting divisions. 



