244 DESCRIPTION OF A MAGNETIMETER, BEING A NEW 



been long known that iron might be rendered magnetical bv 

 percussion ; but I am not aware that the precise effect of posi- 

 tion has ever been suggested. I remain, &c. 



William Scoresby Jun. 

 To Dr Brewster, 1 



Sec. Royal Soc. Edin. j 



From a series of observations on the anomalies in the posi- 

 tion of the Magnetic Needle on ship-board, made on the coast 

 of Spitzbergen in the years 1815 and 1817, I was led to attri- 

 bute the deviation of the compass to the combined attraction of 

 all the iron in the ship having a vertical position, as it appear- 

 ed that, in high latitudes, horizontal bars of iron had scarce- 

 ly any influence on the needle. The result of my investiga- 

 tions, with the several inferences drawn from them about the 

 time of observation, were published in the Philosophical Trans- 

 actions for 1819. In the present paper, therefore, it is my 

 intention only of communicating to the Royal Society some 

 curious facts which have arisen out of a further investigation 

 of the subject. 



For examining into the phenomena of the polarity of iron 

 arising from position, &c. I constructed, about the month of De- 

 cember 1819, an apparatus, of which, with improvements recent- 

 ly made, the following is a description. It consists of a small 

 table of brass, A, Plate XIII. Fig. 1., 4^ inches square, and 3f 

 inches high, having a plate of brass C attached to it by hinges, 

 and moveable by means of the wheel and pinion D, E, through 

 an arch of 250 degrees of a vertical circle. This plate has a 

 small straight groove running from end to end, in the line a a, 

 for the purpose of receiving bars of metal, the polarity of which 



is 



