69 



Therm. Corrected. 



MaX'Brunnen (Medicinal.) 



1850. July 2, Noon. 49*4 Troughton. 48*9 



Booklet (Four miles from Kissingen, Chalybeate.) 



July 1, 4 P.M. 50-7 Troughton. 50-2 



Kapelle (Chapel at Kissingen, fine fresh- water spring in front of, 

 accompanied by much gas.) 



June 28, 6 p.m. 51-5 A 3. 



The above agree usually within a few tenths of a degree with the 

 observations made fully a month later in 1838. 



5. On a Method of Discovering Experimentally the Relation 

 between the Mechanical Work spent and the Heat 

 produced by the Compression of a Gaseous Fluid. By 

 Professor. William Thomson. 



The important researches of Joule on the thermal circumstances 

 connected with the expansion and compression of air, and the ad- 

 mirable reasoning upon them expressed in his paper,* " On the 

 Changes of Temperature produced by the Rarefaction and Conden- 

 sation of Air ;" especially the way in which he takes into account 

 any mechanical effect that may be externally produced, or inter- 

 nally lost in fluid friction, have introduced an entirely new method 

 of treating questions regarding the physical properties of fluids. 

 The object of the present paper is to show how, by the use of this 

 new method, in connection with the principles explained in the 

 author's preceding paper on the Dynamical Theory of Heat, a 

 complete theoretical view may be obtained of the phenomena ex- 

 perimented on by Joule, and to point out some of the objects to 

 be attained by a continuation and extension of his experimental 

 researches. 



The formulse investigated in this paper are divided into three 

 classes : — 



1. Those which are certainly true for all substances, or for all 

 fluids. 



2. Those which are necessarily true for any fluid subject to 

 Boyle's and Daltoa's laws of density. 



■^ Phil. Magazine, 1845. Vol. xxvi., p. 3G9. 



