474 THIRD REPORT 1833. 



MAGNETISM. 



1. That a series of observations upon the intensity of Ter- 

 restrial Magnetism be executed in various parts of the king- 

 dom, similar to those which have been carried on in Scotland 

 by Mr. Dunlop. (Some experiments, made in consequence of 

 this recommendation, by Dr. Traill, are given in the published 

 Reports of the Association, page 557.) 



2. That observations should be made in various places with 

 the Dipping-needle, in order to reduce the horizontal to the 

 true magnetic intensity. 



* A standing Committee, charged with promoting these 

 objects, has been appointed, consisting of Professors Christie, 

 Forbes, and Lloyd. The latter gentleman has undertaken to 

 make observations on the magnetic intensity in Ireland, before 

 the next Meeting of the Association. 



'& 



Desideratian noticed in Prof. Christie s Report. 



* A regular series of observations conducted in this country 

 on the diurnal variation of the needle. 



ELECTRO-MAGNETISM. 



The Committee recommend for further examination the Elec- 

 tro-magnetic condition of mineral veins. (Consult on this sub- 

 ject the paper of Mr. Fox, Phil. Trans. 1830.) 



RADIANT HEAT. 



Desiderata noticed in Professor PoweWs Report. 



1. Improvement of the means of obtaining accurate indica- 

 tions of small degrees of radiant heat : the thermo-multiplier 

 of MM. Nobili and Melloni to be subjected to examination', 

 (vol. i. p. 297, &c.) 



Determination of the following questions (p. 298.) : 



2. Do the ratios of the conducting powers of substances re- 

 main the same for all thicknesses ? 



3. It is alleged that in certain cases simple heat is radiated 

 freely and directly through transparent media : Is it meant that 



' Professor Forbes gave an account of the performance of this instrument 

 at the Cambridge Meeting. 



