62 Motkes respecting New Books, 



been wfU understood. It has been generally held that vertical 

 bars of iron, which have remained long in that position, acquire a 

 magnetic property, the upper end being a south pole, and the 

 lower a north one. But it now appears that this property is com- 

 municated instantaneously, and that tlie polarity may be reversed 

 by reversing the position of the bar. In southern latitudes the 

 upper end is a north pole. 



No seaman should be without this work, which satisfactorily 

 explains several of the phenomena pointed out by Captain Flin- 

 ders and Mr. Bain in their works on the same subject. The au- 

 thor mentions in an advertisement at the end of his tract, that he 

 had not heard of Mr. Barlow's work on Magnetic Attractions, 

 till his own was at press. We think his pages produce internal evi- 

 dence of the fact. These two works should accompany each other. 



Being no seamen, we may suggest nonsense; but it has occurred 

 to us that advantage might sometimes i)e found from having a 

 compass aloft, in one of the tops. Whether any system of gim- 

 bles could keep a compass steady enough for use, in such a situ- 

 ation, others must determine. 



yiddress of M. Hoeiie IVronski to the British Beard of Lojigi- 

 tude, upon the acluul State of the Miilhamatics. their Re- 

 form, and Tipon the neto Celestial Mechanics, gii'ing the dc" 

 Jinitive Solution of the Problem oj Longitude. 

 The author is a foreigner, and the work is a translation from 

 his French, This will sufficiently account for the gallicisms which 

 «ire found in it. The author came to tliis country to offer the 

 fruits of his labours and discoveries to the Board of Longitude, 

 and complains of the reception he met with. It is obvious that, 

 •allured by the premiums at the disposal of the Board, he put 

 himself to great tn)uble and expense, and involved himself in dif- 

 ficulties winch deserved commiseration, — and, inany will be in- 

 clined to thiiik, some more substantial remuneration than he 

 has vet obtained, even if bis proffered discoveries slioidd provo 

 nugatory. It is natural that a ])erson in his situation shoulrt put 

 a high value upon labours which he firndy believes offer the most 

 ■impo-rtant results ; and we cannot doubt that the Board, — should 

 it even cost son-.e trouble, with, in their estimation, little promise 

 of benefit to science, — will yet be at some pains to ascertain, by 

 fill impartial investigntion, and by affording the author ev^ry fa- 

 cility to demonstrate his problcnts, the real merits of wlvat he 

 offers. Dr. Young has publicly acknowledged that the author 

 has detected a Idunder in bis Postscript on Refractions, published 

 in the Nautical Almanack for 1822. This fact shows that, on the 

 subject of refraction at least, the author is not a mere pretender 

 to mathematical knowledge. 



Irately 



