1072 



THORAX. 



TABLE U Progression of the Vital Capacity 



Volume, with the Stature from the above. 



The first column contains the heights be- 

 tween five and six feet, increasing arithmeti- 

 cally two inches at a time, as 1. 3. 5., &c. ; 

 the next two columns are the result of ex- 

 periment ; the first upon 1012 cases at an 

 earlier period of the investigation ; the next 

 at a later period, when the whole cases con- 

 joined amounted to 1923 cases. We found 

 that the men from 5 feet to 5 feet 2 in. gave a 

 mean vital capacity of 176 cub. in.; the men 

 two inches taller a mean of 191 cub. inches ; 

 the next, 207 cub. in., and so on ; thus the 

 volume increases as we descend the column. 

 Finding the progression so regular, we arranged 

 a fourth column, containing a series of numbers 

 in perfect arithmetical progression, commencing 

 with 174, and increasing sixteen at every subse- 

 quent step, corresponding to the two inches of 

 height successively added. We found, upon 

 comparing the two columns of observations 

 with the column of calculation, that there was 

 a close resemblance. The increase of sixteen 

 for every two inches is of course the same 

 as eight for every single inch ; hence the 

 rule deduced upon nearly 2000 cases (and 

 subsequently confirmed by double that number) 

 viz. That for every inch of stature, from 5 

 feet to 6 feet, eight additional cubic inches of air , 

 at 60, are given out by a forced expiration. 

 This brings the detailed matter of a series of 

 tables and calculations into a point, and easy 

 of remembrance, the more so as extended ob- 

 servations upon nearly 5000 men have brought 

 the column of observation so close to the 

 column of regular progression, that it is only 

 necessary now to take the column of regular 

 progression as a standard for examining the 

 condition of the lungs as to their perme- 

 ability for air, and the mobility of the tho- 

 racic boundaries. 



If we recollect that at the height of 5 feet, 



TABLE V Vital Capacity Volume (temp. 60 



F.) necessary to Health at the Middle Period 

 of Life. 



Vital 

 capacity. 



174 

 182 

 190 

 198 

 206 

 214 

 222 

 230 

 238 

 246 

 254 

 262 



8 in. the vital capacity is 230, we can recollect 

 the rest by adding or subtracting eight to or 

 from this number, for every inch of stature 

 above or below 5 feet 8 in., between 5 and 6 feet. 

 These numbers may be taken as expressions of 

 certain conditions of the thorax, an expression 

 of mobility relative to breathing, and conse- 

 quently an expression of the permeability of 

 the lung. It therefore follows that whatever 

 affects the mobility of the thoracic bound- 

 aries, or the permeability of the lungs, the 

 amount of that cause is expressed by the 

 volume of the vital capacity. Incipient disease 

 is quick in affecting the vital capacity; the 

 amount of the injury therefore is readily 

 measured. We are at a loss to assign any 

 just reason why the vital capacity is rela- 

 tive to the height, which is regulated by the 

 length of the limbs, and not by the length of 

 the trunk of the body. We have found by 

 experiment, that whatever be the standing 

 height, the sitting height is nearly the same 

 in all persons of between 5ft. and 6ft., and 

 if not actually the same, yet it is not a rule 

 that the tallest men sit the highest ; for in- 

 stance, one man standing 6ft. O^in. measured 

 from his seat 2ft. 1 If in., whlie another who 

 stood 5ft. 6in., sat 3ft. high ; therefore the 

 length of the trunk bears no constant propor- 

 tion to the length of the legs. And we found 

 that men who stood low, breathed less than 

 men who stood higher, but who sat the same 

 height. Thus jig. 706. represents two men ; 

 A. stood 4ft. 4|in., B. 5ft. 9in. ; they were 

 of the same age and circumference of the 

 chest. The weight of the short man was 7st. 

 2|lb., that of the taller man lOst. 3lb. Yet 

 their sitting height was precisely the same, as 

 is shown in Jig. 707. Nevertheless, the vital 

 capacity volume of the shorter man was 152, 

 and that of the taller man 236 cubic inches ; 

 so that the man who stood the shorter, but 

 who sat as tall, if not taller, breathed eighty- 

 four cubic inches less than the man who stood 

 seventeen inches higher. The mobility of the 

 chest of the taller man was early four inches, , 

 that of the shorter man three inches. We ex- 

 amined several such cases with similar results. 

 The average vital capacity volume at all heights 

 is about 230 cubic inches. The greatest 



