231- British Association fo}' the Advancemeiit of Science. 



dual, similar to those which have recently been carried on in Scot- 

 land by Mr. Dunlop. 



Should the Committee succeed in finding some individual ready 

 to undertake the task, they propose that an application should be 

 made to the Royal Society of Edinburgh, for permission to make 

 use of the Standard Needle belonging to them, and constructed 

 under the direction of Professor Hansteen of Christiania. 



It appears to the Committee of considerable importance that a 

 certain number of observations should be made throughout Britain 

 with the Dipping Needle, in order to reduce the Horizontal to the 

 true Magnetic Intensity. 



Note. — The time of three hundred vibrations should be observed, 

 and the methods of observation and reduction should be the same 

 as have been employed and described by Humboldt, Hansteen, and 

 others. 



Electro-Magnetism. — The Committee recommend as an important 

 subject for further prosecution, the examination of the Electro- 

 Magnetic condition of Metalliferous Veins. The Committee would 

 refer for the details of what has been already done upon this sub- 

 ject, to the paper of Mr. Fox in the Philosophical Transactions for 

 1830, and would propose that the experiments should be extended 

 to veins which traverse, as in some of our mines, horizontal and dis- 

 similar strata. 



Optics. — That Dr. Brewster be requested to prepare for the next 

 meeting a report on the progress of Optical Science. 



Acoustics. — That the Rev. Robert Willis be requested to prepare 

 for the next meeting a report on the state of our knowledge con- 

 cerning the Phccnomena of Sound, and the additions which have 

 been recently made to it. 



Heat. — That Professor Powell be requested to prepare for the 

 next meeting a similar report respecting Heat. 



Electricity. — That Professor Gumming be requested to prepare 

 for the next meeting a similar report on Thermo-Electricity, and 

 the allied subjects in which recent discoveries have been made. 



Chemical Committee. 



It appears to the Committee of supreme importance that chemists 

 should be enabled, by the most accurate experiments, to agree in 

 the relative weights of the several elements, hydrogen, oxygen, and 

 azote, or, which amounts to the same thing, that the specific gravity 

 of the three gases should be ascertained in such a way as would 

 insure the reasonable assent of all competent and unprejudiced 

 judges. 



They think it highly desirable that the doubts which remain 

 respecting the proportions of azote, oxygen, &c. in the atmosphere 

 should be removed ; that the proportions of azote and oxygen in 

 nitrous gas and nitrous oxide should be strictly determined j and 

 that the specific gravities of the compound gases in general should 

 be more accurately investigated. 



They recommend that the members of this Committee, and British 



chemists 



