ELECTUICJTV. 35'/ 



tube, i. e. by holding the extremity C or B in the 

 hand, and presenting the other extremity to the 

 prime conductor, when the machine is in motion. 

 They may also be fixed in any other position, by 

 having connecting wires. 



To show that the Electric Fluid prefers a short pas- 

 sage through the Air, to a long one through good 

 Conductors. 



Bend a wire about ten feet long, at the ends of 

 which fix a piece of glass G, to keep the knob A B 

 at a proper distance, so that they may slide within 

 half an inch of one another, if required; then con- 

 nect the chains belonging to the sliding wires with 

 the hook of the battery and the discharging rod, 

 and send the charge of a battery through it. On 

 making the explosion, a spark will be seen between 

 A and B, which shows that the electric fluid 

 chooses rather a short passage through the air, 

 than a long one through the wire. The charge, 

 however, does not pass entirely through A and B, 

 but part of it also goes through the wire, which 

 may be proved by putting a slender wire between 

 A and B; for on making the discharge, with only 

 this addition in the apparatus, the small wire will 

 hardly be made red hot: whereas, if the large 

 wire A D B be cut in D, so as to discontinue the 

 circuit A D B, the small wire will be melted, and 

 even exploded, by the same shock that before 

 made it scarcely red-hot. In this manner the con- 

 ducting power of different metals may be tried, 

 using metallic circuits of the same length and 

 thickness, and observing the difference of the pas- 

 sage through the air in each. 



a a 3 



