366 Researches in Magnetic Electricity. 
the shock was so great as to render it difficult to keep even the 
tips of the fingers upon the wires. A single thermo-electric pair, 
heated and cooled, connected with the large wire, gave a bright 
spark and a shock, which could be felt as far as the wrist. The 
use of three pairs in sequence, enhanced the results. It must here 
be observed, that the shocks and sparks, are not thermo-electric, 
but magneto-electric. The pure thermo-electric spark, I appre- 
hend, has never yet been seen. I obtained, a long time since, 
sparks and shocks from a thermo-electric pair, in connexion with 
Henry’s flat spiral. But in that case also, the results were purely 
secondary, or magneto-clectric, the copper spiral while transmit- 
ting a cwrent, in fact, representing a magnet with axial poles. I 
have always maintained the position, that a shock direct, cannot 
be obtained from a single pair of plates, or any elementary current, 
arrangement whatever. Although recently, we have 
the high authority of Faraday, that iodide of potassium, and 
some other compounds may be decomposed, by a single galvanic 
pair, yet even admitting this to be fully established, I see no rea- 
son for retracting, and may continue safely to assert, that an ele- 
mentary battery however large, cannot afford a direct appreciable 
shock. In Faraday’s experiment, the decomposition was the re- 
sult of uninterrupted action, but in all experiments hitherto, where 
shocks have been obtained by the aid of a single pair, they have 
been obtained as single impulses, immediately consequent to the 
completion of the circuit, as with the large magnet of Prof. Cal- 
lan, or as in all other cases, to the interruption of the circuit. In 
anew instrument, shortly to be described, I have a singular in- 
stance of an electro-magnet, affording shocks, not only on the com- 
pletion and breaking of the circuit, but even while the battery 
current is passing without interruption. It appears irrational to 
suppose for a moment, that the shock obtained by breaking the 
circuit with coiled conductors, can receive any augmentation from 
the conjunction of the primitive and ‘secondary currents, for the 
presumption is, and the fact itself seems sufficiently obvious, that 
the sparks and shocks indicating a new and secondary current are 
directly consequences of the dissolution of the primitive current. 
In other words, the effects produced by the breaking of a primi- 
tive elementary current, are due solely to magnetic excitation, 
and have no connexion with that primitive, except that of cause 
and effect. In fact, strictly speaking, the results thus observed 
. 
