The Sun.
London, England, 1858-01-08 00:00:00

ROYAL INSTITUTION.

The interest taken in Professor Faraday's lec-
tures seems to increase as the course approaches its
termination. An hour and a half before the lecture
begins perions collect round the entrances to the
theatre to obtain good places, and on the opening
of the doors there is a crash and a scramble like
that at the pit doors of a theatre. Yesterday, when.
the fifth lecture was delivered, an elderly gentle-
man and a lady fell to the floor in ruhieg inside,
but fortunately without sustaining any sawn in.
jury, and every seat was filled sonic time before the
appointed time for the lecture. The Prince of
Wales occupied the seat in front of the lecture table
as usual.

The effects of the induction of electricity weret
further exemplified and explained by Professor
Faraday, who commenced by giving illustrationi
of the influence of differently shaped surfaces. A,
cube of wood covered with tinfoil was used in the
first illustration. The cube was charged with elec.
tricity when placed upon an insulating stand, and
a small square of metal, insulated by a handle of
shellac, was applied first to the centre of one of the
flat sides of the cube, and afterwards to its corners,
to thbw that a much larger quantity of electricity is
concentrated at the latter points than on the flat
surface. When the metal carrier, after touching
the flat surface, was applied to the electrometer,
the leaves only slightly diverged ; but when 'the
corners of the cube were touched the gold leaves ex-
panded widely. The influence of surfaces was
still further exemplified by points, from which
the electricity exerted by the large machine was
dissipated se rapidly as to prevent it from exhibit-
ing strong electrical effects. One experiment, which
illustrated the different effects of induction when
operating on metal points, and on pointed non-
conducting bodies, was very curious. A small rod
of metal was balanced so as to allo w it to turn freely,
and at each end was fixed a piece of tinfoil rounded
at one part and pointed at the other. When this
apparatus was electrified, the_balanced rod turned
rapidly round, as it would have done had a jet of
water issued from each point by the re-action of
the air. Similarly shapedpieces of thick paper were
then substituted for the tinfoil, and when the ap-
paratus was again electrified the rod tuned round
in the opposite direction—the points moving so as
to meet the air instead of being repelled by it. • The
apparatus called a condenser was then explained,
and ale() the action of the eleetrophorns—the phe-
nomena of both depending on induction—but it
must be admitted that the connection between those
phenomena and the property of induction was not
very clearly explained. Professor Faraday next
proceeded to notice the discovery of the Leyden
jar, and he exhibited the experiments which led
Muschenbrook to make the discovery of the electric
shock, which frightened that philosopher so ranch
that he would not take another for the whole king-
dom of France. A small phial was partly filled
with water, and a cork, with a nail pushed through
it, constituted the original Leyden jar. This
simple apparatus when held to the conductor of
the electrical machine collected a chargoaufficient
to make Professor Faraday start. He then proceeded
to illustrate the successive improvements in the Ley-
den jar, and to prove that the charge is contained
in the glass, and not in the metallic castings on
each side, which only serve to conduct the electricity..
Thus, for instance, a conical tumbler with a movable
outside and inside casing was charged, and the
metal carvings having been removed and applied
to the electrometer exhibited no trace of electricity,
but when restored to their places inside and out-
side the tumbler, a report was made when the dis-
charging rod was applied to the outside and to the
connecting rod. An illustration was also afforded
of the fact that the electricity of a charged Leyden
jar becomes manifest only when connection is made
between the outside and the inside. The lid with
the wire and brass knob of an ordinary Leyden jar
were removed, and on then dropping a suspended
ball inside no electricity was communicated to it,
nor was any given off by the outside of the charged
jar, but when connection was made between the
inside and outside coatings, after the lid was put
on, a smart explosion proved that the jar contained
a strong charge. To pursue the invention on to' its
more powerful effects, in the accumulation of elec-
tricity in quantities so great as to be dangerous,
the large electrical battery of the institution was
charged and exploded. Professor Faraday, at the
conclusion of his lecture, showed a simple arrange-
ment which had been made by one of the young
gentlemen attending his lectures, for accumulating
electricity, as in the Leyden jar. It consisted of a
finger glass partly filled with water, into which a
glass tumbler was introduced. When electricity
was communicated to the water in the tumbler it
became charged like a Leyden jar.