462 Mr. Herapath's Reply to Mr. Tredgold. [Dec. 



phers will, by this unexpected fact perceive with pleasure with 

 what fidelity the results of experiment are represented by our 

 theory, even when warped with the notions of caloric. But 

 striking as the coincidence is, we labour under a disadvantage 

 by not knowing the temperature of the water and its proportion 

 to vapour. Had we these data, there is no reason for doubting 

 but our theory would have made the coincidence even more per- 

 fect than it is. 



To make this theorem also answer the views of the proposer, 



we have only to substitute 1000 for t, and 10 \f 10 E for t' in the 

 case of the detached boiler, which gives latent heat = 

 '11000 E \ 85 



( 1000 - E ) to + — 



V 3 / 36 



E 



48 

 X 



to + 1 100 



/ 10997 E \ 85 _ 



( 3 100 °J " + 36 E 48 



r— x -Tpj. taking the elasticity at 32° 



Fahr. for 1000. In the case of the attached boiler, we have 

 t = p -1 e and t' = <p~ l E which substituted in the formula give 

 latent heat = 



|— .*->E .(p-'e-^.-'O'-Cp-'E)^ .«> + |(t_,E)' 4g 



to + 1 X 100000* 



In page 270 of the present volume of the Annals, I have given 

 some calculations from a theorem similar to that I have deduced 

 in the third case ; but as I have not experimental results, but 

 only calculations from a theory which is found to agree nearly 

 with observation within a certain extent, it will be useless to 

 attempt a further comparison. 



(To he continued.) 



Article IX. 



Reply to Mr. Tredgold. By John Herapath, Esq. 



(To the Editor of the Annals of Philosophy.) 



DEAR SIR, Cranford, Hounslo-j),Nov. 12, 1821. 



It has ever appeared to me to be a more honourable course, 

 even in unprovoked attacks, to give the writer an opportunity of 

 discovering and correcting his own errors than triumphantly to 

 expose them to animadversion. In your Annals for October, T 

 took this course with your correspondent X. and Mr. Tredgold, 

 who had thought proper to attack my writings. I perceived, as 

 I stated, errors and misconceptions in the observations of both, 

 which I wished them to rectify rather than myself. X. has taken 



