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fixed magnets. This fine light had before then sent its piercing 
rays for a considerable period across the English Channel, and 
its bright beams, projected from the lighthouse of Dungeness, 
had been the admiration of so many gazers on the shores of 
France. Mr. Holmes’ revolving wheel was a somewhat cum- 
brous way of getting the electric power, and some important 
modifications of this means have been made in France. 
After some years Mr. Wilde struck out a plan more powerful 
and less liable to derangement, and which, though ponderous as 
a machine, is far more compact than its predecessors. His 
principle is in one sense the reverse of Mr. Holmes’. Instead of 
an army of small keepers revolving against a circle of batteries 
of small magnets, he causes one gigantic keeper to revolve inside 
a huge electro-magnet — a revolving canal draining a saturated 
mountain — kept at the point of saturation by a separate charging 
battery of permanent magnets. 
The action and power of Mr. Wilde’s machine will be best 
understood by a general description of its parts and their separate 
and combined actions. The main and most prominent portion, 
that which not only does the most work but most attracts the 
eye by its massive dimensions, is the electro-magnet ( u , x , u). 
This consists of two vertical plates (u, u) of rolled iron, 4 feet 
in length and 3 feet 3 inches wide; in thickness 1^ inches. 
Each of these is coiled with 4,800 feet of insulated cable of 13 
strands of copper wire 0T25 inch in diameter ( t , t), the total 
weight of the coils being over 1 \ tons. Instead of the soft iron 
core being turned over in an arch, as in the common smaller horse- 
shoe magnets, these two flat sides are connected together at the 
top by an iron slab or hollow bridge ( x , x), 1 foot 4 inches 
across. At the base of the electro-magnet and upon which its 
massive sides are secured, is the magnet-cylinder ( b ' b', c' c'), con- 
sisting of two large cast-iron segments ( b ' b' and c' c ') magneti- 
cally separated in their entire length by intermediate mechanical 
connections of brass ( d ' d'), which form with them one cylindrical 
case in the bore of which the enormous Siemens’ armature 
(s' s s' s'), 10 inches in diameter, is made to revolve. Upon the 
top of this powerful electro-magnet is stationed a battery (a) of 
20 permanent magnets, each of which is capable of sustaining a 
weight of 20 lbs. The magnet-cylinder for this adjunct is formed 
in the like manner of two segments of cast-iron (6) mechanically 
joined by blocks of brass ( d , d), which metal not being a magnetic 
conductor effectually insulates the two iron segments, whilst it 
combines those two separate parts into one entire piece of 
machinery. The armature (g) which revolves within this 
magnet- cylinder is 3-| inches in diameter, and is wound round 
longitudinally about an iron core by 80 feet of covered copper 
wire. Such is the machine. Now the object of its action is to 
