Intelligence and Miscellaneous Articles. 147 



always very small, were not unfrequently negative. In September 

 the lower hemisphere appeared decidedly the hotter of the two. The 

 maximum difference rather exceeded 2° (by the galvanometer), being 

 almost identical with the result obtained in the month of March in 

 the opposite direction. Moreover, this maximum occurred from the 

 14th to the 16th September, which also corresponds with the epoch 

 of the greatest depression of the solar equator." 



Sig. Secchi remarks, that the influence of the solar spots upon 

 the temperature is very striking. Sometimes a spot which did not 

 occupy more than y^*^ of the aperture of the pile, caused the tem- 

 perature to fall 3°, or about yyth of the whole intensity. He found, 

 however, by isolating the spot with a diaphragm, that it exercises a 

 sensible influence even in the obscure part. 



XXIV. Intelligence and Miscellaneous Articles, 



ON THE TEMPERATURES OF CONDUCTORS OF ELECTRICAL 

 CURRENTS. 



To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, 



I FEEL some difliculty in writing this note, and yet I think it 

 requisite to say a closing word upon a subject which has 

 already occupied too much of your space. It is nearly ten years 

 since Mr. Adie made his experiments : would not a careful repeti- 

 tion of them at present show more wisdom upon his part than a 

 reliance upon results which have such a mass of scientific evidence 

 against them ? With regard to his theory of the metallic cross*, I 

 have one request to make of Mr. Adie ; and that is, that he would 

 kindly place his pencil on the point C, where he supposes the cur- 

 rent to be generated, follow the course of the current, and get back 

 to C, without passing through the battery. Some oversight must, I 

 imagine, have occurred in Mr. Adie's dissection of the cross ; as the 

 matter stands at present, I frankly confess my inability to under- 

 stand it. 



John Tyndall. 

 Queenwood, Jan. 1853. 



REMARKS ON CHEMICAL AFFINITY. BY PROF. BUNSEN. 



The force which produces or destroys chemical combination is 

 influenced by a great variety of circumstances. Its effects are modi- 

 fied by the action of light, heat, electricity, and likewise by the 

 relative masses of the bodies acting upon each other. It is moreover 

 influenced by the state of aggregation of the bodies, and their con- 

 tact with others of a different kind. Consequently, chemical afl&nity 

 may be regarded as a function of all these various determining con- 

 ditions ; and in order to ascertain the value of the force, it will be 

 suflScient to determine mathematically the form of that function. 



* Phil. Mag. for January 1853, p. 46. 



