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Researches on Heat. Second Series. By James D. Forbes, Esq. 

 F. R. SS. L. & E., Professor of Natural Philosophy in the 

 University of Edinburgh. 



{Read 2d May 1836.) 



§ 1. On the Use of' the Thermo-Multiplie?'. § 2. On the Polariza- 

 tion of Heat by Tourmaline. § 3. On the Laws of the Po- 

 larization of Heat by Refraction. § 4. On the Laws of the 

 Polarization of Heat by Reflection. § 5. On the Circular 

 Polarization of Heat. 



1. The first series of these researches, in the exact form in 

 which they are printed, were laid before the Royal Society on the 

 19th January 1835. The whole of the experiments there de- 

 scribed were made, and the paper written and printed, within a 

 space of time little exceeding two months. This haste, unfa- 

 vourable to composition, I considered as a less evil than postpon- 

 ing for a period of time, which must have been considerable, the 

 publication of a class of facts which might be said almost to em- 

 brace a new science. The professional duties which pressed upon 

 me during the whole continuance of those experiments, then call- 

 ed imperatively on my attention, and during the remainder of 

 the Session my time was devoted to them. The summer I de- 

 voted to a foreign excursion, some of the results of which I after- 

 wards digested ; and it was not till the commencement of the 

 winter session which has just closed, that I prepared, with a fresh 

 stock of health and spirits, to reinvestigate the whole subject of 

 the Polarization of Heat, and to assign numerical values to the 

 effects, whose existence I had before been contented to prove. 



