On the Simultaneous Superficial Distribution of Heat, 311 



drawing of the aluminium spectrum is given, with zinc and cadmium 

 for comparison. 



The author has also described and figured the mode of absorption 

 of the invisible rays by solutions of various alkaloids and glucosides. 

 Bodies of these classes, he finds, are usually intensely opaque, acting on 

 the invisible spectrum with an intensity comparable to that with which 

 colouring matters act on the visible. This intensity of action causes 

 the effect of minute impurities to disappear, and thereby increases 

 the value of the characters observed. It very often happens that at 

 some part or other of the long spectrum a band of absorption, or 

 maximum of opacity, occurs ; and the position of this band affords 

 a highly distinctive character of the substance which produced it. 



Among natural crystals, besides the previously known yellow 

 uranite, the author found that in adullaria, and felspar generally, a 

 strong fluorescence is produced under the action of the rays of high 

 refrangibility, referable not to impurities, but to the essential con- 

 stituents of the crystal. A particular variety of fluor-spar shows 

 also an interesting feature, though in this case referable to an im- 

 purity, exhibiting a well-marked reddish fluorescence under the 

 exclusive influence of rays of the very highest refrangibility. This 

 property renders such a crystal a useful instrument of research. 



With some metals broad, slightly convex electrodes were found to 

 have a great advantage over wires, exhibiting the invisible lines far 

 more strongly, while with some metals the difference was not 

 great. 



The blue negative light formed when the jar is removed, and the 

 electrodes are close together, was found to be exceedingly rich in 

 invisible rays, especially invisible rays of moderate refrangibility. 

 These exhibited lines independent of the electrodes, and therefore 

 referable to the air. This blue light has a very appreciable duration, 

 and is formed by what the author calls an arc discharge. 



The paper concludes with some speculations as to the cause of the 

 superiority of broad electrodes, and of the heating of the negative 

 electrode. 



" On the Loess of the Valleys of the South of England and of the 

 Somme and the Seine." By Joseph Prestwich, Esq., F.R.S. 



"On the Simultaneous Distribution of Heat throughout superficial 

 parts of the Earth." By Professor II. G. Hennessy, F.R.S. 



The principal object of this memoir is to develope the laws of the 

 distribution of temperature in the portion of the atmosphere in con- 

 tact with the earth, and to point out the connexion between the phe- 

 nomena of aerial temperature and those of soil and oceanic tempera- 

 ture. The author maintains that hitherto no perfect physical repre- 

 sentation of the distribution of heat over the earth's surface has 

 been obtained. Humboldt's luminous method of representing the 

 distribution of mean temperatures necessarily presents us with the 

 temperatures of places at those hours of local time when the tempe- 

 rature happens to be equal to that of the entire day. But such hours 



