TRANSACTIONS OF THE SECTIONS. 15 
On a new Electrical Machine, and upon the Electricity of the Atmosphere. 
By Joun Nott. 
This paper treated at great length of electrical currents and of the atmospheric 
electricity, by way of a preliminary to the consideration of terrestrial magnetism. The 
author insisted on the close analogy between the voltaic pile and a magnet. The dif- 
ference between voltaic and frictional electricity he conceives to be, that the former is 
in the conducting wire, the Jatter on its surface, and therefore decomposed by what- 
ever approaches it. Besides, the voltaic pile exhibits the two electricities and the cur- 
rent in which they unite; whereas the ordinary frictional machines develope and 
maintain but one electricity and no current. Among the novelties presented by the 
paper, may be mentioned the description of what the author calls the rheo-electric 
machine, in which both electricities are developed by friction. ‘ It consists of a cir- 
cular plate of glass and another of resin, both supported upon a horizontal axis, and 
set in motion by a winch handle; the rubber of the vitreous plate is connected by a 
metal rod with the rubber of the resinous one; and the conductor of the latter plate 
is also connected by a metal rod with that of the former, and thus a complete circuit 
is formed, as in the voltaic pile. The distribution of the electricity of this instrument 
is also analogous to that of the pile. For example, the electro-motive disturbance is 
produced by the plates; the rubber of the vitreous plate is rendered negative, that of 
the resinous one positive; and the conductors are also in opposite electric states, and 
their remote extremities are therefore analogous to the poles of the pile. When the 
conductors are connected by a conjunctive wire, it is natural to suppose that the ac- 
cumulated electricities flow along its surface in opposite directions, for then an elec- 
tric current is formed, which permanently deflects the magnetic needle, and the de- 
flection is according to the direction of the current. The direction of motion of this 
current may be varied at pleasure; for instance, in order to fix our ideas, let us sup- 
pose the plates of this instrument and the axis of the conductors to be lying in parallel 
planes, perpendicular to what is called the magnetic meridian, the conjunctive wire 
connecting the conductors being bent at right angles, a portion of it will then be in 
the meridian, and the metal rod connecting the rubbers will be parallel to this portion. 
If now a magnetic needle be suspended above the conjunctive wire, and the resinous 
plate, which we will suppose to be placed north of the vitreous one, be connected with 
the earth, then a current of electricity passes from the resinous plate, and consequently 
flows along the conjunctive wire from north to south; the needle is then permanently 
deflected towards the west. If the needle be placed beneath the conjunctive wire, 
the deflection is towards the east. When the vitreous plate is connected with the 
earth the current flows from the vitreous plate, and the deflections are in the opposite 
directions.” In the course of his experiments with this machine, the author found 
that all the parts of it which were made of brass became, by electrization, highly mag- 
netic, and retained their magnetism for some time. The character of the magnetism 
thus produced will be understood by conceiving an orthographical projection of this 
instrument to be drawn upon a horizontal plane: it will be a parallelogram, of which 
the conjunctive wire will form one side, and the rod connecting the rubbers another : 
then all the brass parts of one half of this parallelogram, cut off by a diagonal line, 
will attract the north pole, and all of the other half the south pole. But if, immedi- 
ately after electrization, either pole of the needle be forced into contact with any part 
of the brass conjunctive wire, it will develope an opposite magnetism to its own, 
and adhere to the wire as it would to a piece of iron. He also proved that water may 
be decomposed by the rheo-electric machine as with the galvanic current. The two 
electricities, as developed by this machine, appeared to him to be visibly different : 
the resinous electricity was subject to remarkable changes of colour, according to the 
state of the atmosphere and the nature of the exciting body. It also struck him that 
electricity is radiated in a peculiar manner from magnetized bodies. Combining this 
observation with a hypothesis respecting the electricity of the globe, viz. that the equa- 
torial parts of the earth are in the resinous (in old language, negative) state of elec- 
tricity, the poles vitreous (positive); while the atmosphere is, in its lower strata, vitreous, 
and in the upper resinous; the author proceeded to exhibit the pheenomena of the 
aurora borealis by direct experiment. ‘1 procured a globe of steel and magnetized 
it. It may not be unnecessary to state how this was effected. I suspended the globe. 
