325 
Biographical Notice of Baron Hermelm. 
at each vibration of the pendulum, until their tensions would ar- 
rive at such a point as to cause a spark to pass between them. 
<c But P is a Leyden jar, furnished with a Lane’s discharging 
electrometer q; a connection is established by means of a small 
chain between it and A, and the distance between the two balls, 
r and s , is considerably less than that between A and C ; there- 
fore the spark will be given to the jar : and a spark will be con- 
tinued to be given at the completion of almost every second vi- 
bration, until it is charged almost as highly as A is capable of 
being charged, or the sparks will continually supply the loss of 
electricity by any defect of insulation, either of the jar, or of any 
conducting body, in connection with its interior coating within 
certain limits. My plates and bob are four inches in diameter 
It has been proposed to adopt large doublers instead of the 
common machines, for exciting electricity in large quantities, 
with a view to the saving of labour ; and Mr Bead has hinted at 
his knowledge of a method to cause the centre plates of revol- 
ving doublers to recede from the others, in proportion as the 
charges advance (a necessary condition, if large quantities of 
electricity are to be obtained) ; but he died without having made 
it public, 
64 Could not a jins screw be cut upon the axis which carries the 
centre plate, passing through the common support of the other 
two, which should partially produce the effect desired ? Or, 
could not such a screw be made to act upon levers, &c., which 
should proportion its recession exactly to the advance of the 
charges ? The affair would not be very difficult to a clever me- 
chanist, perhaps.” 
Art. 'KlsJL.—~Biographical Notice of Baron Samuel Gustavus 
Hermelin. 
m . 
X HE memory of this philosopher should be equally dear to 
geographers and those who cultivate the mining art. 
* The contacts of the wires do not impede the velocity of the vibrations, be- 
cause they are made small enough to act as springs of a required force ; but the 
electric attractions of the plates and bob do tend to do so. The pendulum is sus- 
pended by two springs, placed one at each extremity of a cross piece, to which the 
rod is attached, for the purpose of preventing the bob from being drawn, by these 
attractions, out of its assigned plane of vibration, as much as possible. 
