THORAX. 



1067 



100 to 60; Mcchli at 52 and 40*; Dr. 

 Herbert, of Gottingen concludes this volume 

 to be " very little." f We have found it to 

 vary from 75 to 100 cubic inches. It must 

 be relative to the absolute capacity of the 

 chest, which varies from 248 to 457 cubic 

 inches. The mean absolute capacity is 312 

 cubic inches. Allowing 100 cubic inches for 

 the heart and large blood vessels, and 100 

 cubic inches for the parenchymatic structure 

 of the lungs, will leave a little more than 100 

 cubic inches for the residual air ; therefore 

 Allen and Pepys's opinion may be relied upon 

 as very near the truth. 



(b) Reserve volume. Goodwyn omits 

 this volume altogether ; and this omission 

 was pointed out forty years ago by a phy- 

 siologist who himself omitted any notice of 

 the complemental air. Kite estimates this 

 at 87 cubic inches ; Davy, by an experiment 

 upon himself, at 77 cubic inches J ; Dr. Bos- 

 tock, from trials upon himself, at 160 or 

 170$; Mechel at 110 cubic inches. || It 

 averages about 100 cubic inches ; our obser- 

 vations range from 70 to 110 cubic inches. 

 It is regulated by the point at which the or- 

 dinary breathing movement commences. 



(c) Breathing volume. This has attracted 

 most attention ; but the discrepancies of 

 opinion are nearly commensurate with the 

 number of observations. It would require 

 years of labour to determine this volume by 

 direct experiment, in a manner to be avail- 

 able to the physician ; and it would re- 

 quire a long time to perfect the observation 

 of it upon a single patient, because these 

 movements are so delicately affected by the 

 mind, so perfectly uncontrollable, and the 

 volume is so small, that a little error would 

 seriously damage the value of the observation. 

 The volume assigned by observers, varying 

 from 3 to 100 cubic inches, is as follows : 



Cub. in. 



- 3 



- 12 

 6 to 12 



3 and 14 



- 13 

 8 or 10 



- 17 

 13 and 17 



|16-5 

 16 to 25 



- 20 

 15 to 40 

 25 to 29 



- 30 



- 35 

 Richeraud, Poland, Gordon, and Ca- 



vallo - - 30 to 40 



Hales, Jurin, Sauvages, Haller, Ellis, 

 Sommering, Thomson, Sprengel, 



* Mechli's Manual Descrip. and Pathological 

 Anat., vol. ii. p. 448. 



- f Bostock, Op. Cit., p. 316 ; and Archives Gen. 

 de Med., t. xxi. p. 412. et seq. 



J Op. Cit, pp. 47, 48. 



Op. Cit. p. 316. 



j| Manual of Descrip. Anat., vol. ii. p. 447. 



Abildgaard - 



Abernethy - 



Keutsch 



Goodwyn 



Lavoisier and Seguin 



Wurzer and Lametheria 



Kite 



Davy 



Allen and Pepys 



Herbst 



Jurin 



Borelli 



Herdolt 



Dalton 



Fontana 



Cub. in. 



Bostock, Chaptal, Bell, Monro, and 

 Blumenbach - - - 40 



Menzies - - 42 to 46 



Reil - - - 40 to 100 



upon an average, it varies from 16 to 20, 

 though we have occasionally found it vary 

 from 7 to 77 cubic inches. Though our ob- 

 servations upon this point are but scanty com- 

 pared with those we made on the vital capa- 

 city, yet from about 80 experiments we con- 

 clude that man in a perfectly quiet state, as 

 when sitting, reading, &c., breathes much less 

 than he does under the ordinary excitement of 

 moving about. We think the perfectly quiet 

 breathing, when we can scarcely perceive any 

 movement (which is by no means uncommon), 

 may be from 7 to 12 cubic inches, and when 

 under ordinary excitement and exercise, from 

 1 6 to 20 cubic inches ; we have known it in 

 one case as high as 77 cubic inches. It is 

 probable that the quantity is relative to the 

 volume of blood to be aerated. Herbert 

 found that adults of smaller stature breathed 

 less than those who were taller.* It is proba- 

 ble that phthisical patients breathe very little, 

 from 2 to 4 cubic inches ; but the number of 

 their breathing movements is greater, which 

 compensates for this small quantity. 



(rf) Complemental volume. Davy, from 

 a single experiment (upon himself), calcu- 

 lates this at 119 cubic inches f ; Kite, at 

 nearly 200 cubic inches. It is regulated 

 by the position of the ordinary breathing 

 movement, which is intermediate between 

 it and the reserve air. It averages, from 

 direct experiment, rather higher than the 

 reserve volume, about 105 or 110 cubic 

 inches. Taking the mean height at 5 ft. 

 8 in. the vital capacity is 230 cubic inches, 

 that is to say 



Reserve air - 

 Ordinary breathing 

 Complemental 



cub. in. 



100 



20 



110 



230 



(e) Vital capacity volume. Jurin and 

 Hales correspond in stating this at 220 cubic 

 inches ; Davy at 213 cubic inches || ; and 

 he remarks in a note, " this capacity is pro- 

 bably below the medium. My chest is nar- 

 row, measuring in circumference but 29 

 inches, and my neck rather long and slender." 

 It is probable the figures 29 are a misprint 

 for 2 feet 9 inches round the chest. Dr. 

 Thomson, from the mean of twelve experi- 

 ments, upon men from fourteen to thirty- 

 three years of age, states it at 186| cubic 

 inches. Dr. Thomson himself could expel 

 193 cubic inches. He mentions that this 

 volume is constant when once determined. 



* Mttller, El. Phys., 1st ed. 8vo., Lond. p. 294 

 vol. i., 1847. 



f Op. Cit. p. 410. 



J Op. Cit. p. 47. 



Hales's Sat., 1732, vol. i. p. 239. 



|j Op. Cit. p. 410. 



