Second Series. — Thermo- Multiplier. 351 



employ a table of reduction, indicating the relation subsisting 

 between the dynamical effect or first arc of impulsion, and the 

 statical effect or that of final deviation. My experiments have 

 given the following results, and the last column indicates the ac- 

 tual intensities taken from the preceding table, corresponding to 

 the statical deviation in second column. 



Dynamical effect, or first Statical effect, or 



arc passed over. Permanent Deviation. Intensity. 



1.0 



1.2 



1.2 



2.0 



2.8 



2.35 



4.0 



4.5 



4.65 



6.0 



6.7 



71 



8.0 



8.9 



9.6 



10.0 



11.1 



12.05 



12.0 



13.2 



14.4 



14.0 



15.3 



16.9 



16.0 



17.4 



19.35 



18.0 19.45 21.75 



20.0 21.5 24.3 



9. The mode of observation by the first impulsive arc I have 

 invariably adopted for obtaining numerical results, and chiefly 

 for these reasons : 1. It saves time, and thus renders consecutive 

 observations comparable. 2. It prevents a long exposure of the 

 pile to heat, which alters the zero point and injures its action. 

 3. It almost annihilates the effect of conduction where substances, 

 capable of retaining heat, are placed between the source of heat 

 and the pile. 



10. It is a remarkable circumstance, that when both the cor- 

 rections obtained from these tables are applied, we obtain (as 

 far as 20° at least) a measure of intensity increasing, almost 

 uniformly, with the arc first run through. This is found to de- 

 pend on the circumstance that the curve, expressive of forces, in 

 terms of the stationary deviation, is convex towards the axis, or 

 the forces increase more rapidly than the arcs ; whilst the curve, 

 expressing the stationary in terms of the momentary deviations, 



3 M 



