THE HUMAN STRUCTURE 113 



P being expressed in grammes and S in square centimetres. This 

 is " Meeh's relation. "( l ) Thus the body of an adult weighing 65 

 kilogrammes has a surface ; 



S = 12-312 sy^OOO 2 == 19,896 square centimetres or 

 T99 square metres, practically 2 square metres. 



If two individuals of different weights are considered (an adult 

 and a child), their surfaces will be to each other a? the cube root 

 of the square of their weights ; thus the surface diminishes less 

 rapidly than the weight. We have : 



S' 12-312 P 71 P 7 ' 2 3 IP 7 * 



S 12- 



For instance, make P' = i P, then - J. Thus if the weights 



vary from 8 to 1, the surfaces will only vary from 4 to 1. There- 

 fore children have a larger surface than adults in proportion to 

 their weight. Accurate methods of estimating the surface of 

 bodies are available, but they are generally complex. ( 2 ) That 

 of Jules Lefevre ( 3 ) appears to be the simplest : the subject is 

 in a pliable garment moulding itself perfectly to the body. Let 

 P be the weight of the garment, p the weight of a square deci- 



p 

 metre of the same stuff ; the relation gives the surface of the 



P 



body. This procedure is very exact if an accurate balance is 

 employed. 



It must be remarked that the surface, volume and density of 

 the human body undergo variations when there is obesity or 

 extreme thinness ; these being causes of which it is difficult to 

 take exact account. 



81. (iv) Weight of the Human Body, The average weight of 

 the human body, with regard to age, for the two sexes has been 

 determined by different authors. The measurements of Quetelet, 

 between the limits of 6 and 60 years (vide the following table 

 and fig. 118) are as follows: 



. (!) Meeh (Zeitsch. f. Biol. vol. xv., p. 440, 1879). The co-efficient K in 

 the formula varies slightly with the state, (thin or fat), of the subject. 



( 2 ) We quote, from memory, a geometrical method due to Bouchard 

 (Comptes Rendus Acad. Sc., 1897, vol. Ixxiv, p. 844) and another, also geo- 

 metrical, but more correct, by B. Roussy (ibid., 17th July, 1911, p. 205, 

 and 14th April, 1913, p. 1171). Roussy even takes into account the surface 

 of the ears and the genital parts. 



( 3 ) Jules Lefevre, BiotnergStique, p. 501 (Masson, Paris, 1911). 



