IMPROVEMENTS IN ELECTRO-MAGNETS AND THEIR APPLICATION TO TELE- GRAPHIC AND OTHER PURPOSES
Year: 1865

page_text: PROVISIONAL SPECIFICATION left by William Clark at the Office of
the Commissioners of Patents, with his Petition, on the 4th January
1865. A communication from abroad by Charles Frédéric Carlier,
Mechanician, of 29, Boulevart St. Martin, Paris.
I, WILLIAM CLARK, of 53, Chancery Lane, in the County of Middlesex,
Engineer and Patent Agent, do hereby declare the nature of the said Inveu-
tion for "IMPROVEMENTS IN ELECTRO-MAGNETS AND THEIR APPLICATION TO TELE-
GRAPHIC AND OTHER PURPOSES," to be as follows:-
Electro-magnets are composed of an iron cylinder covered spirally with
metal wire, through which passes the electric current. It has been hitherto
cousidered indispensable to insulate the several coils of the helix, for which
purpose a covering of silk, cotton, gutta percha, or varnish, more or less
impervious, is applied. I have found by numerous experiments that this
insulation is not so useful for the development of the maguetic power as is
generally supposed, and have sought to employ a metal wire without any
insulating covering whatever, attaining results so far beyond even anticipation
as to induce me to employ this means for the economic construction of electro-
magnets, which also enables me to obtain much greater effect by its adoption.
This Invention thus comprises not only improvements in electro-magnets, but
is also applicable to the frames of galvanometers, magnetic bobbins, and in all
other instances where electro-magnetic power is to be created. This improved
system possesses no distinctive peculiarities, the same method of winding the
wire on the bobbins being adopted, and the same relative conditions retained
[Price 8d1

page_text: as regards the length and the thickness of the wire, with the exception that from
experience I have found that although the coils of the magnetising helix may
be insulated throughout a row of coils, it is different with regard to the
relation between the rows. Thus it is essential for obtaining a good result
that each row be separated from that superposed by means of a paper covering
of sufficient length to envelop the extreme coils. It is also necessary for the
first row to be insulated from the core of the bobbin if of metal, although this
may be obviated by the employment of wood for the purpose; and further the
wire connecting one bobbin with another should be prevented from touching
the iron of the electro-magnet.
From experiments made with an electro-magnet on this principle I have
found that while an ordinary electro-magnet of given dimensions can sustain
in contact a weight of but twenty ounces, one constructed according to these
improvements and as above indicated, will sustain a weight equal to two
pounds. Its attractiveness at distances apart has furnished still more decisive
results; thus when an electro-magnet with covered wire will attract at one-
thirtieth of an inch distance, a weight of but one-third of an ounce, one on
this system would attract one ounce at the same distance, the same superiority
being maintained whatever may be the resistance to be overcome.
The advantages of these improvements will be readily understood; first,
considerable economy is realised in the manufacture of electro-magnets, all
the silk covering of the wires being saved; in the second place, the effect being
much more energetic, they may be employed of the sinallest dimensions, and
so quicken the action of the electro-magnet; lastly, through the suppression
of the extra current by the absence of insulation in the coils, there will be an
absence of sparks at the cominutators, thus permitting of a more rapid motion
of the armatures; these improvements are especially applicable to electro-
magnetic induction bobbins.
The Invention thus consists,-
1st, in constructing electro-magnets, galvanometric frames, and other
electro-magnetic apparatus based on the employment of circuits of uncovered
metal wire, by which is understood a wire uncoated with any insulating
substance, such as cotton, silk, gutta percha, gum lac, or any suitable varnish.
2ndly, in the application of these improvements to all kinds of electro-
magnetic apparatus used in telegraphy and otherwise.