208 Proceedings of the British Association for [Sept. 



2. Mr. S. Harris explained and exhibited to the Section, 

 a new species of instrument of extreme delicacy for mea- 

 suring electrical forces. It is of the same kind as the torsion 

 balance of Coulomb, and similar to it in general appearance, 

 but the peculiarity is this : instead of a needle suspended 

 by a single wire or fibre, which fibre undergoes the torsion 

 against which the antagonist force of the electrical repul- 

 sion is to act, the needle is here suspended by two parallel 

 fibres run together, one on each side of its centre ; and the 

 effect may be most shortly described, by saying, that nei- 

 ther of the fibres undergoes torsion, but the plane (in which 

 they both lie when at rest) undergoes torsion, or is twisted 

 into a surface of double curvature. The degree to which 

 this is carried, is here counterbalanced by a weight; or 

 gravity thus constitutes the antagonist force, instead of the 

 resistance of the fibre to torsion, in Coulomb's construction. 

 It is difficult to give the contrivance a good descriptive 

 name, since that of torsion-balance cannot be applied, but 

 of its extreme sensibility and accuracy, no doubt can be 

 entertained. There are also several very ingenious improve- 

 ments in the mode of arranging the indices and reading 

 off from the scale, but these are independent of the peculiar 

 and beautiful principle above described, and could not be 

 rendered intelligible but in detail. It is to be hoped the 

 author will give such details to the public. 



3. Professor Powell read an abstract on certain points 

 connected with the recent discoveries relative to radiant 

 heat. 



The object of his communication was to state, that the 

 author felt particular satisfaction in observing, that M. 

 Melloni, (in his second Memoir) describes a repetition of 

 the experiment originally made by him, and recorded in the 

 Phil. Trans, for 1825 with perfect success, by means of his 

 extremely delicate apparatus. The confirmation is the more 

 complete, as M. Melloni appears to take up the inquiry 

 with a different object. 



It is thus now established beyond question, that lumi- 

 nous hot bodies are sending out two distinct sorts of heat, 

 or two distinct heating agents, at the same time, differing 

 in their properties and mode of operation. 



Hence, the whole series of results of M. Melloni must 



