IS 13.] emitted from the Lungs during Respiration. 337 



that it is low, perhaps somewhat lower than the usual minimum. 

 An argument in favour of this opinion is, that immediately after 

 waking, and during the aet, as it were, of expergiscence, I have 

 always found the quantity very considerable, even _ in some 

 instances as high as the maximum. This, however, is only of 

 short duration ; in half an hour the quantity, as before observed, 

 is' rather below the standard. 



The depressing passions of every kind, and in short whatever 

 produces that peculiar sensation which induces yawning, sighing, 

 or any other deep inspiration,* have evidently the effect of dimi- 

 nishing the quantity, these appearing in fact but to be so many 

 involuntary acts by Which, as before observed, the system gets 

 rid of its retained carbon. Anxiety and solicitude have a similar 

 effect. One day the quantity was rapidly approach 1 ng to its 

 maximum when a friend came in, whom 1 was particularly 

 anxious to show the fact : but the extraordinary solicitude I felt 

 on the occasion entirely defeated my purpose, and the quantity 

 was less than I had almost ever seen it. Had this occurred but 

 once, I should not have noticed it ; but something of the kind 

 has happened to me frequently. 1 mention it also to convince 

 those who may be inclined to repeat my experiments, of the 

 absolute necessity there is of keeping the body and mind in a 

 state of the greatest possible uniformity. If this be not attended 

 to the results will be discordant and unsatisfactory, as they were 

 for the first day or two with me ; so much so, indeed, that 1 was 

 almost ready to give up the matter in despair, and to imagine 

 that there was nothing like uniformity in it. By degrees, how- 

 ever, the laws which I have attempted to establish began to 

 develope themselves ; and having discovered these, and more- 

 over acquired the habit of respiring and conducting the experi- 

 ments with uniformity, I obtained the results which are now laid 

 before the public. 



Such, then, are the chief observations which have occurred 

 to me in this investigation. The application of them to the 

 establishment of the laws I have laid down are, 1 flatter myself, 

 rendered so easy by the accompanying tables and experiments, 

 that 1 deem it unnecessary to trouble my readers with it.f 



• Thus we yawn when we arc sleepy to counteract the effects of (hat 



approaching slate of the system which favours the retention of carbon and 



induces sleep, \Ve yawn and stretch purselves in the morning after waking 



to dispose of ill carbon which bad beeu retained during; that act. So also 



yawning «hcn we are hungry, and sighing when »<■ are in di tres«, may be 



considered as extraordinary acts, bj which that carbon is expelle.l which the 



diminished energy of the iyi tem inthes : states ia unable to throw oil l» > common 



iu( which, ;.i the same time, its welfare demand*. 



• [I may be proper te observe, that " the inspii id expirn I ns 



were omewhat deeper than natural, though no( a greal deal. The for er 



ade through the no<-e, and the latter into i\«- bladder, till the 



d number m i. The results obtained are evidently (o be uu- 



Vol. II. N V. Y 



