134 Professor Ty?idall [June I, 



We have every reason to suppose that the secondary current thus 

 developed is of the same nature as the primary which produced it ; 

 and hence we may infer, that if we conduct the secondary away 

 and carry it through a second spiral, it, in its turn, will act the 

 part of a primary, and evoke a tertiary current in a spiral brought 

 near it. This was illustrated by experiment. First, two spirals 

 were placed opposite to each other, through one of which the cur- 

 rent of the battery was to be sent ; the other was that in which the 

 secondary current was to be aroused. The ends of the latter were 

 connected by wires with a third spiral placed at a distance, so that 

 when the secondary current was excited it passes through the third 

 spiral. Underneath the latter, and separated from it by a sheet of 

 varnished glass, was a fourth spiral, whose two ends were connected 

 with the universal discharger, between the knobs of which a quantity 

 of gun-cotton was placed. When the battery was discharged 

 through the first spiral, a secondary current was aroused in the 

 second spiral, which completed its circuit by passing through the 

 third spiral : here the secondary acted upon the spiral underneath, 

 developed a tertiary current which was sufficiently strong to pass 

 between the knobs, and to ignite the gun-cotton in its passage. It 

 was shown that we might proceed in this way and cause the tertiary 

 to excite a current of the fourth order, the latter a current of the 

 fifth order, and so on ; these children, grandchildren, and great 

 grandchildren of the primary being capable of producing all the 

 effects of their wonderful progenitor. 



The phenomena of the extra current, which exists for an instant 

 contemporaneously with the ordinary current in a common voltaic 

 spiral, were next exhibited ; and the question whether a spiral through 

 which a Leyden battery was discharged exhibited any similar 

 phenomena was submitted to examination. It was proved, that the 

 electric discharge depended upon the shape of the circuit through 

 which it passed : when two portions of such a circuit are brought 

 near each other, so that the positive electricity passes in the same 

 direction though both of them, the effect is that the discharge is 

 weaker than if sent through a straight wire : if, on the contrary, the 

 current flow through both portions in opposite directions the 

 discharge is stronger than if it had passed through a straight wire. 

 A flat spiral was taken, containing 75 feet of copper wire ; one end 

 of the spiral was connected with a knob of the universal discharger, 

 and the other knob was connected with the earth : between the knobs 

 of the discharger about four inches of platinum wire were stretched ; 

 on connecting the other end of the spiral with the battery a discharge 

 passed through it of such a strength that it was quite unable to 

 raise the platinum wire to the faintest glow. The same length of 

 copper wire was then bent to and fro in a zigzag manner, so that on 

 every two adjacent legs of the zigzag the current from the battery 

 flowed in opposite directions. Wiien these 75 feet of wire were 

 interposed between the battery and the platinum wire, a discharge 



