THORAX. 



1075 



from this as a starting point the weight at 

 any height may (so far as our limited ob- 

 servations warrant) be readily calculated. For 

 instance, the weight is, at the height of 5 feet 



155"2 



8 inches, - = 2-282 Ibs. for every inch of 

 bo 



stature, or 27'38 Ibs. for every foot of 

 stature. The bulk or weight of bodies 

 having the same relative proportions, is as 

 the third power (cubes) of either of their 

 diameters : thus, if a person 67 inches high 

 weighs 148'44 Ibs., a person 69 inches high 



,. . ,/69\3 69X69 X 69 



should weigh (-) x 148-44= 



Taking the height from 67 to 71 inches, 

 we have as follows : 



TABLE Z. The calculated Weight compared with 

 the observed Weight, according to the above 

 Form. 



X l48-44= 



67 x u? x 6? 

 x 148-44= 162-14 Ibs. The 



3 3 



weight at that height, from observation, was 

 162-08 Ibs., a similarity too close to be acci- 

 dental. 



The weights vary as the 2'75th power of the 

 height, and not as the 3rd power. The rela- 

 tion between the two is quite close enough 

 to show, that there is a very intimate connec- 

 tion between the height and the weight. The 

 observation is made upon 1276 men at the 

 middle period of life. 



We have found that the vital capacity in- 

 creases 42 cubic inches with the weight from 

 100 Ibs. to 155lbs., and from 155 Ibs. to 200 Ibs. 

 the effect is balanced by minus 5 and plus 5 

 cubic inches. In the first division there is an 

 increase of 42 cubic inches ; the weight then 

 comes into power, and disturbs the regular 

 progression for the next division ; therefore we 

 may say there is in the second division a de- 

 crease of 42 cubic inches in the vital capacity 

 volume from the effect of weight. We repre- 



Fig. 708. 



no 

 120 



120 

 130 



130 

 140 



170 



170 



180 



180 

 190 



190 



200 



Vital capacity. 



Circumference of 

 the chests. 



The Effect of Weight on the Vital Capacity. 



sent this by a curve, fig. 708. The continuous 

 curve is the line of vital capacity crossing the 

 perpendicular lines of progressive weights. 

 The curve of volume ascends, and attains its 

 highest at 160 Ibs., and from thence it is 

 nearly horizontal to 200 Ibs. According to 

 this, the vital capacity increases nearly in the 

 ratio of 1 cubic inch per Ib. from 105 to 155 Ibs., 

 and from 155 to 200 Ibs. there is no increase. 

 This illustration of the effect of weight is cal- 

 culated at one height, viz. 5 feet 6 inches ; 

 therefore to this height only these points of 

 weight (from Hi to 14 stone) refer. We 

 have noticed that the weight increases in a 

 certain ratio with the height, and that the 

 weight at 5 feet 6 inches affects the vital 

 capacity in the relation just mentioned, com- 

 mencing when the weight exceeds 7 per cent 

 upon the average weight. We may, perhaps, 

 connect this same relation with the other 

 heights through the arithmetical progression 

 of inch by inch. For example : the weight 

 of men of 5 feet 1 inch is 199'9 Ibs. ; to this 

 add 7 per cent (8'395 Ibs.), making 128'2 Ibs. ; 



again, the tallest men, 5 feet 11 inches, weigh 

 174-2 Ibs. ; to this add 7 per cent'(12'2 Ibs.), 

 making 186-4 Ibs. : therefore, at the height 

 of 5 feet 1 inch a man must exceed 128 Ibs., 

 or 9 stone 2 Ibs., and the 5 feet 1 1 inches' 

 man 186 Ibs., or 13 stone 4 Ibs., before weight 

 may be expected to diminish the vital capa- 

 city volume in the relation of 1 cubic inch 

 per Ib. for the next 25 Ibs., 2| stone being 

 the limit of our calculation. When the man 

 exceeds the mean weight (at each height) 

 by 7 per cent, the vital capacity decreases 1 

 cubic inch per Ib. for the next 35 Ibs. above 

 this weight. Beyond this it is not improbable 

 but that the decrease of the vital capacity is in 

 some geometrical progression. Below the mean 

 weight we have never found by experiment, 

 that the vital capacity is affected by weight. 



The cause of the difference of weight 

 between men is involved in much obscu- 

 rity.* We may in fact consider the usual 

 weight of a man as his mean weight and 



* See Chambers, Gulstonian Lect. 1850. 



*3z 2 



