330 Change of Rate produced in a Clock by Magnetic Action. 



In the above diagram the upper of the strong curved lines 

 shows the total change produced by attraction, the lower the 

 total change produced by repulsion : they are formed from the 

 sixth and seventh columns of the second Table. The dotted lines, 

 which on the ris-ht-hand side of the diagram are lost in the 

 strong lines, represent the values of P, as given in the third 

 Table. The length of ordinate between the dotted line and the 

 strong line in each case represents the effect of I as contained 

 in the same Table : this combined with P, bending P upwards in 

 both cases, produces the results indicated by the strong lines. 



It remains to be stated that the length of the clock-pendulum 

 to the effective end of the pendulum-magnet (the upper end) was 

 33*25 inches ; also that the centre of the magnet in that part 

 swung to 1*34 inch on each side of the perpendicular, correspond- 

 ing to a total arc of 4° 38'. This is the normal arc, with the pendu- 

 lum-magnet only in position. With both magnets in position 

 and magnetic action existing, the extent of swing, if required, 

 can be inferred from the numbers given in the last two columns 

 of the first Table. The total weight of the pendulum as fitted 

 with its magnet was 7 lbs. 14 oz. avoirdupois. 



The magnets were similar in size, their dimensions being, 

 length 5*6 inches, breadth 06 inch, and thickness 0*13 inch. The 

 following observations of the deflection of two light pocket com- 

 pass-needles by the magnets may give an idea of their strength. 

 The magnets were placed in an east and west direction, and in 

 reversed positions of poles, both on the east side and on the west 

 side of the compass-needles. Each of the following numbers is 

 consequently the mean of four observations. Needle A is the 

 heavier : — 



At a distance of 6 inches (measuring from the nearest end 

 of the magnet to the centre of the compass-needle) — 



A. B. 



o o 



Pendulum-magnet deflected needle . . 50^ 49 

 Fixed „ „ . . 39| 39i 



At a distance of 12 inches — 



Pendulum-magnet deflected needle . . lOf 12^ 



"Fixed 7-3- 9^ 



The pendulum-magnet appears to be stronger than the other. 



As respects the possible application of the principle now 

 treated of to the special object of changing the rate of a clock, 

 it will be understood that, in such application, means must be 

 provided for delicately moving in a vertical direction the magnet 

 corresponding to that here called the fixed magnet : then the 



