46 Mr. Harvey on the Effects of Magnetism 



through the centre of the time-keeper. The detached rate of the 

 machine was + 2".0, but which was immediately converted into 

 + 3".4, by its application to the ferruginous mass, in the position 

 denoted by F, Fig. 7, the balance being in this situation at its least 

 distance from the ball. By turning the time-keeper, however, a 

 quadrant, to bring it into the position of F, Fig. 8, this rate 

 declined to + 2".5 ; and, by again moving it through a quadrant, 

 to cause it to assume the position of F, Fig. 9, the daily variation 

 remained nearly constant ; but, on turning it through another 

 quadrantal arc, the rate increased to + 3": 3; and on finally 

 removing the machine from the influence of the iron mass, the daily 

 change was found to be + 3".0. This chronometer, therefore, gained 

 in consequence of the magnetic action of the Iron Shell, and lost 

 when that power ivas removed from it ; and in the diferent situations 

 assumed by its balance with respect to the magnetic meridian, it 

 sometimes gained, and at other times lost. 



From the preceding experiments it may be therefore inferred, 

 that the rates of chronometers are affected by the induced magne- 

 tism of iron, and that its effects are of a variable and uncertain cha- 

 racter ; in some cases developing its energies with considerable 

 force, and in others, producing but feeble and unimportant effects; 

 imparting an acceleration in some positions, and a retardation in 

 others ; — influencing different chronometers in different degrees, 

 and according to opposite laws ; in some producing augmenta- 

 tions of rate, and in others, with the attracting force operating 

 under the same conditions, as to direction and power, disclosing 

 results precisely the reverse. Of these variable effects, as in the 

 case of what is commonly denominated permanent magnetism, 



