M. Fourier's Law of the Radiation of Heat. 103 



and again from the 4th to the 12th of April; the remainder, 

 however, of this month was for the most part gloomy and 

 exceedingly cold, and on the 25th the summit of Cross Fell 

 was pretty thickly covered with snow. During the first three 

 weeks of May, keen cutting winds prevailed generally from 

 the East; on the 2nd, there was snow several inches in depth 

 in the vicinity of Tindal Fell, and on the 1 5th and 16th we 

 had several smart hail-showers ; in short, it was not before the 

 22nd that the weather became at all warm and seasonable. 



Vegetation, as might naturally be expected, made but little 

 progress; and upon the whole the spring of this year was per- 

 haps more backward than the very late one of 1829. 



The summer and autumn which followed, however, were fine 

 and remarkably dry, the harvest early, and the crops in this 

 district, generally speaking, were exceedingly good, more 

 particularly on cold elevated grounds, where the farming pro- 

 duce was scarcely ever recollected to have been more abun- 

 dant, or to have been secured in finer condition. 



Carlisle, November 10, 1832. 



XIX. Abstract of the principal Demonstrations qfM. Fourier, 

 relative to the Mathematical Law of the Radiation of Heat. 

 By Baron Maurice, Member of the Institute of France, and 

 Professor of Analytical Mechanics in the Academy of Geneva. 

 Translated by James D. Forbes, Esq. F.R.S. L. <iy Ed. 

 F. G.S. Sf-c. Communicated in a Letter to Sir David Brewster. 



My Dear Sir, 

 r T v HE precis of Fourier's Demonstrations, from which the 

 ■*• following translation is taken, was put into my hands in 

 manuscript, by my friend Baron Maurice of Geneva, last 

 month. It was written for the Supplement to M. Prevost's 

 work on Heat, which has since appeared. As I have not ob- 

 served any account of this part of Fourier's labours in Eng- 

 lish works (and, indeed, the writings of that distinguished 

 man are too little known in this country), I think the present 

 notice may not be unacceptable ; more especially as the ori- 

 ginal Memoir of Fourier, in the fifth volume of the Memoirs 

 of the Institute, is really obscure. In this tract M. Maurice 

 has reduced the theory to a few simple propositions, which he 

 has given with all that copiousness of reasoning which di- 

 stinguishes the writings of Fourier, when he is establishing 

 fundamental propositions upon which a complex superstruc- 

 ture is to be raised : the first demonstration in particular is 

 quite in the Newtonian style. I have adhered closely to the 



j 



