253 



of the respective attractive forces or intensities ; the total force, AS 

 also demonstrable by the instrument, being as the square of the ac- 

 cumulation. Let, for example, the quantity of charge communicated 

 to the jar be 100 measures, and the attractive force, or intensity at 

 distance one inch, be 144 degrees, and suppose intensity of residual 

 force at the same distance=*08. In this case we have the simple 

 proportion 100 measures : x measures : : V/T44 : '/'W: : 12 : '283 



1 00 v *28S 

 and quantity of residual electricity == = 2'35 measures 



nearly ; so that of the original 1 00 measures of charge communicated 

 to the jar, rather more than ^th remains undischarged in this case. 



The author here offers some explanatory observations on the rela- 

 tive dimensions and extent of coating of the unit of measure and the 

 relative value of the measures quoted, and he thinks if electricians 

 would agree to recognize a standard instrument of this description, it 

 would be attended with very considerable advantage, as in the case of 

 other standard instruments. The unit of measure he employs ex- 

 poses about 9 square inches of coating ; it is about 4 inches long, '8 

 of an inch in diameter, and J^th of an inch thick ; distance of ex- 

 ploding balls '05 of an inch. Similar observations were applied to 

 the thermo-electrometer, the ball of which is 4 inches in diameter, 

 *aiid has a wire of platinum through it of '01 of an inch in diameter. 

 The dimensions of the attracting discs of the hydrostatic electrometer 

 are also noted, which in these experiments were 4 inches in diameter ; 

 the suspended disc weighs 82 grains. The discs are carefully gilded ; 

 5 degrees of the arc of measure represents a force of 1 grain, that is 

 to say, a weight of 1 grain added to either side moves the index 

 5 degrees of the scale. Having offered these preliminary remarks, the 

 author proceeds to the following experiments : 



Experiment 1. Variable charges, amounting to 50, 100, 150 

 measures, were successively accumulated on different jars, exposing 

 from two to six square feet of coating, and the residual charges due to 

 each noted ; these were found to be as the total charge. Thus the 

 residual charge for 100 measures was in every case double that for 

 50 measures. 



In a succeeding Table are noted measured charge ; exploding 

 distance ; intensity at distance 1 inch ; residual measures and thermo- 

 electric effect of discharge. It appears by this Table that residual 



VOL. XI. T 



