IS 14.] emitted from the Lungs in Resphatlo'n. 333 



From the first two of these tables and the annexed diagram, 

 [Plate XXIV.] (in which the dark curved line represents the 

 commencement, of twilight, the dotted line the time of the sun's 

 rising, and the asterisms the day and hour when the experiments, 

 &c. took place,) it will be seen, that the increase has always 

 uniformly occurred soon after the commencement of twilight, and 

 before sun-rise. It is also deserving of notice, that the increase was 

 greatest and most remarkable when the nights were longest, and 

 that it gradually became less as they grew shorter;* a circumstance 

 which, however, appears to have been chiefly owing to a diminution 

 having taken place in the usual minimum quantity towards the 

 morning, either probably from the fatigue of watching or from 

 drowsiness. 



With respect to the increase towards noon formerly noticed, when 

 the quantity was found at its maximum, I have only the instances 

 constituting Table III. to offer in addition to what was then ad- 

 vanced. No exception to this part of the law has occurred to me. 



The time of the evening diminution appears to be about the tcr- 

 inination of twilight. I have not, however, had opportunities of 

 verifying ibis in the manner I could wish, owing chiefly to the late 

 lioui* of dining, ike. which might be supposed to interfere with 

 tli<> results. V et in Tables I. and III. some facts in favour of this 

 mption may be observed : thus on Jan. 5, the minimum seems 

 to have occurred between live and six, p. m.; on May 12, about 

 eleven, p. m. ; and in Aug. 1813. during twelve days, at a mean 

 about s 1, 3a', p. in. ; periods not far distant from the terminations 

 of twilight at these different times. In further corroboration, also, 

 It may be mentioned that no negative instance has occurred to me. 

 Hence Law I. in my former paper requires to be somewhat altered, 

 ind inttead of the periods there mentioned as the commencement 



* l regret much dial Circnm tan •- did not permit me to make the experiment! 



•l-iirc, uhen (he twilight in liiii latitude continues the whole 



improbable that the quantity gradually dimloltaei to 



'[lit, aiiu - .In increat* iu a timilar manner. 



