444 Annual Meeting of the 



tions to which the processes now in use must be submitted, 

 in order to improve the quality of the metal ? 



VII. — It appears to result from the experiments of M. Ja- 

 cobi. that the electro-magnetic force may be employed as a 

 new impelling power ; which, as much by the simplicity of 

 the apparatus, as by the absence of all danger, will be prefe- 

 rable to any other force of which we have hitherto availed 

 ourselves. 



In consequence of this the Society request that it be prov- 

 ed by now researches, First, how far the impelling electro- 

 magnetic force may be augmented to this end ? Secondly, 

 what is the apparatus by which a given electro-magnetic force, 

 equivalent, for example, to three or four horses, can be pro- 

 duced ? Thirdly, what are the metals and acids which may 

 be employed with most advantage ? And what form is it ne- 

 cessary to give to these metals, and how must they be ar- 

 ranged, to reduce them into powerful electro-impellers, acting 

 with the least loss of metal, and the greatest economy of acid ? 

 Vide 'Memoire sur Fapplication de TElectro-magnetisme au 

 mouvement des machines,' by M. H. Jacobi, Doctor and 

 Professor at Dorpat : Potsdam, 1835. And Messrs. Steatingh 

 et Becker, Algem-Konst, en Letterbode, No. 54 and 55, " E- 

 lectro-magnetische Wagen." 



The Society this year proposes the following ten questions 

 to be replied to before the 1st of January, 1840. 



I. — No place in the kingdom of the Netherlands being as 

 yet determined with exactness by means of astronomical ob- 

 servations, the Society desires that the latitude and longitude 

 of one or more places in the Netherlands be determined by 

 astronomical observations. The decision of the Society will 

 depend more upon the exactitude of the observations, and the 

 neglecting no precautions which the present state of astrono- 

 my requires, than upon the instrument made use of; and it 

 is anxious that the observations made, should in no respect 

 yield in accuracy to those of other countries. 



II. — The Society wishes for a clear and precise description, 

 as well as a complete theory, of the prismatic circle of reflec- 

 tion, invented by Steinheil, and perfected by Ertel ; with a 

 comparative examination of that instrument, as well as of the 

 nautical sextant, and the common circle of reflection. 



The Society desires that the uses of this instrument in as- 

 tronomy and navigation be exactly explained ; and that the 

 advantages which it possesses over the above-named instru- 

 ments be pointed out, and the changes noticed which may 

 render it less expensive, and of more general use. Vide the 



