488 HEIGHT AND WEIGHT IN RELATION TO BUILD 



Although in general fat individuals seem to have a relatively low specific 

 gravity, one very thin individual (the last on the list) also has a low specific gravity. 

 Under the limitations of the technique used the correlation between slightness of 

 build and specific gravity does not seem close. In Meeh's studies of volume (table B, 

 p. 543), the specific gravity of two new-born infant cadavers averages 1.047. Three 

 males, with a trunk volume of 43.8 to 50.3 per cent of the total volume of the 

 body, give an average specific gravity of 1.055; while five with a relative trunk 

 volume of 50.8 to 56.6 per cent give an average specific gravity of 0.969. Of two 

 young women, one, with a relative trunk volume of 50.0 per cent, gives a specific 

 gravity of 1.006; the other, with a relative trunk volume of 49.7, gives a specific 

 gravity of 1.016. The specific gravity of the body as awhole is thus greatly influenced 

 by the amount of expansion of the thorax. According to Ziegelroth (1896), the 

 difference between the volume in expiration and that in inspiration in the adult may 

 be over 3 liters. 



There is no evidence that the specific gravity of the adult body differs greatly 

 from that of the infant, although the greater relative amount of water in the infant's 

 body and the relatively small amount of bone might lead one to infer that the 

 infant's body would have a lower specific gravity. There is probably more gas 

 normally present in the adult body. Donaldson (1903) cites a table from E. Bis- 

 choff , in which it is shown that while the relative weight of the skeleton varies little 

 from infancy to maturity, that of the muscles nearly doubles, that of the thoracic 

 and abdominal viscera is decreased by one-third, that of the brain is decreased to 

 one-sixth to one-eighth of the infantile proportions, that of the skin to one-half, and 

 that of the fat is greater in the adult female than in the infant, less in the adult 

 male than in the infant. 



The volume of a pound of water is approximately 27.68 cubic inches at 4 C. 

 At 37 C. (98.5 F.) it is 27.862 cubic inches. The specific gravity of a 3-inch cube 

 (27 cubic inches) weighing a pound would therefore be 1.0252 at 4 C. or 1.032 at 

 the temperature of the body. These last figures approximate the specific gravity 

 of the body, during quiet respiration, chest unexpanded. It is therefore convenient 

 to consider a pound of the human body as equivalent to a 3-inch cube. A pound 

 occupies less space than this in regions like the hand, where the tissue has rela- 

 tively high density, and more in regions containing gas. The estimate is sufficiently 

 accurate for general purposes. If desired, allowance may be made for variations in 

 specific gravity in different parts of the body, or in individuals of different build. 



Height-weight index of build. The volumes of objects of the same shape but of 

 different sizes vary as the cube of a given diameter through these objects. The 

 volumes of the bodies of individuals of the same external form but of varying heights 

 vary as the cube of the stature multiplied by a factor which is conditioned by the 

 form of the body, as TT is conditioned by the form of a sphere. This factor, in the 

 case of the relation of volume to stature, expresses the part of a space equal to the 

 cube of the height occupied by the volume of the body. Thus, if we assume that 

 27 inches is the volume of a pound, the volume of a man weighing 150 pounds 



