124 MR HARVEY on a Remarkable Case of Magnetic Intensity 



By placing the oscillating bar three quarters of an inch above 

 the centre of the glass-crystal, the magnetic intensity was found 

 to be 94.36 ; and at the same distance above the centre of the 

 bottom of the brass-case, it amounted to 100.63. When the 

 Chronometer was turned so as to bring its side below the bar, 

 in being upwards, the intensity was 98.51 ; and on determining 

 it on the opposite side, or when ix was uppermost, it amounted 

 to 94.02. When the cover of the Chronometer box was closed, 

 and the intensity determined at the before-mentioned distance 

 above its middle, the measure of the attraction became 99.13. 

 The intensity therefore was the greatest near the bottom of the 

 brass-case. 



This chronometer appeared to have been constructed with 

 every possible care, to avoid the introduction of magnetism. The 

 handles of the box, the hinges and screws, the lock, staples and 

 key, were all of brass; still, from the anomalous results above pre- 

 sented, the variations of intensity were more considerable than 

 could have been anticipated, considering the very small quantity 

 of steel that appeared in it. These variations are indeed incon- 

 siderable when compared with the changes of intensity exhibited 

 in the former instance ; but are sufficient to prove that magne- 

 tism exists in Chronometers, when, from the precautions em- 

 ployed in their construction, we should have imagined it alto- 

 gether removed. 



That the application of magnets to Chronometers does not 

 in all cases communicate magnetic qualities of a very powerful 

 kind, may be inferred from the example of another Chronometer, 

 which had been frequently employed in inquiries connected with 

 magnetism, for many months, and which was subsequently exa- 

 mined by the apparatus of COULOMB. The oscillating cylinder 

 was placed one inch above the crystal, and the intensity deter- 

 mined in four positions of the time-keeper, namely, when its xn 

 o'clock mark was directed successively to the four cardinal points 



