224 Description of E. M. Clarke’s Electrepeter. 
the experiment, as it is only one spark that shows the fact. Should 
the director rest on the ball so as that two or more sparks are ob- 
tained from the armature you fail. Bring the ball of the Leyden 
jar in contact with a delicate gold leaf electroscope and the leaves 
will be diverged. Very little practice will make you perfect in de- 
veloping their effect. The jar is charged to a very low intensity 
indeed ; but I found that after diverging the gold leaves, if I put my 
hand on the electroscope so as to discharge it and the gold leaves 
collapse ; on touching the electroscope with the ball of the jar, again 
the leaves diverged with as much energy as before. I again dis- 
charged the electroscope, and again produced a divergence : this I 
repeated thirteen times, with the same effect each time, from the 
one charge. I had not time to pursue the experiment further, but 
would be glad to know to what extent it could be carried. The Jar 
I used was eight inches deep, five and a half inches diameter, open 
at the top; the tinfoil coatings were six and a half inches deep. 
Arr. II -Discripitb of E. M. Crarke’s rte from the 
Annals of Electricity, No. 1. Vol. I. 
To W. Srurcron, Esq.—Dear Sir—Understanding from you 
that descriptions of new philosophical instruments will find a ready 
insertion in your valuable work, I therefore send you a description 
of an instrument of my construction for changing the direction of 
electric currents, named by my worthy classical friend, Dr. Murphy, 
an Electrepeter. This instrument, you, sir, as a public lecturer, 
can fully appreciate ; knowing the facility it affords of showing the 
changes that are produced when the directions of current are Te- 
versed. 
The most interesting appli- 
cation of this instrument is that 
when applied to an apparatus 
of your invention for showing 
the attraction and repulsion of 
voltaic currents when induced — 
in a mobile wire frame, timing a 7 UMN a 
MS en 
* Tt willh es pre of Dr. 
at p. fi Vol. “xxii. of this Journal, and called the Dynamic 
Page, described 
Multiplier.—Ep, 
