On the Transmission of Calorific Rays. 109 
Now, the question is, will it be possible to reconcile these 
facts with the latter law ? 
I found that when the magnets referred to, adhered to 
each other at their terminal edges only, as shown in the 
annexed figure, it requized a much greater force 
to separate them than when the two surfaces, or 
ends a, e, were together. This may, perhaps, be 
attributed to a better contact in the former case 
than in the latter; and I conceive that if the con- 
tact had been still more perfect, the force would 
have been reduced one half at less than z;',, of an 
inch. The fact, moreover, proves, I think, that the 
greatest force of magnets, when in contact at their 
dissimilar poles, is not fixed in their axes, or at any 
appreciable distance from their points of junction. 
Under these circumstances the distribution of their 
united forces is, I consider, much the same as it is 
in the case of a single magnet. as 
XXI. Remarks on M. Melloni’s and Professor Powell’s Papers 
on the Transmission of Calorific Rays, inserted in Lond. and. 
Edinb. Phil. Mag. for December 1835 and January 1836. 
By H. Hupson, M.D., M.R.L.A.* 
N referring to the remarks which M. Melloni has done me 
the honour to make relative to a communication which 
I read to the Physical Section of the British Association}, I 
beg to say, that I stated in the paper that I considered my 
experiments with the thermo-muitiplier as zmperfect, and 
merely mentioned them as indicating a method of determining 
a point on which some doubts were still entertained. 
I have since adopted the method alluded to, which has fully 
confirmed the correctness of M. Melloni’s observations; and 
as it appears capable of being advantageously employed in 
some branches of the investigation, I shall briefly describe it. 
ABCD isa square, mahogany board, on which two rectan- 
gular brass plates (each 4 inches wide), E FG H and FILK, 
are fixed (as in fig. 1, p. 110,) at right angles to each other and 
divided into half inches; at C MI O a plate of brass is fixed 
perpendicular to the board, forming a complete screen to T 
(the thermo-electric pile), except through a square opening 
(at N) equal to the section of the pile. A second brass screen 
EI is fixed in like manner perpendicular to the board, and 
* Communicated by tke Author. 
+ An abstract of the communication here referred to will be found in 
Lond. and Edinb. Phil. Mag., vol, vii. p. 297.—Eprr. 
