IMPROVED MEANS OF ISOLATING AND TESTING THE ISOLATION OF THE WIRES OF ELECTRIC TELEGRAPHS
Year: 1854

page_text: LETTERS PATENT to Felix Marie Baudouin, of Paris, in the Empire of
France, and of 16, Castle Street, Holborn (City), London, for the
Invention of "IMPROVED MEANS OF ISOLATING AND TESTING THE ISOLATION OF
THE WIRES OF ELECTRIC TELEGRAPHS."
Sealed the 19th June 1855, and dated the 22nd December 1854.
PROVISIONAL SPECIFICATION left by the said Felix Marie Baudouin
at the Office of the Commissioners of Patents, with his Petition, on
the 22nd December 1854.
I, FELIX MARIE BAUDOUIN, of Paris, in the Empire of France, and of
16, Castle Street, Holborn (City), London, do hereby declare the nature
of the said Invention for "IMPROVED MEANS OF ISOLATING AND TESTING THE
ISOLATION OF THE WIRES OF ELECTRIC TELEGRAPHS " to be as follows, viz. :-
This Invention consists, first, of new or improved means for producing and
rendering durable the isolation of electric telegraph wires by the use of
asphaltum aud bituminous and fatty bodies in general; said substances being
not only used for merely painting or coating the wires, but most expecially
mixed with other matters, so as to form a mastic for cementing with or
burying in them the wires.
With this mastic I either form blocks or pieces resembling kennel stones
with multiple compartments, or tubular ducts, which may be soldered together
or not, and in which the wires are completely seperated from each other i
[Price 8d.]

page_text: or else the wires are imbedded in solid blocks or continuous pieces of this
bituminous mastic, which are run or cast on said wires, so as to fix and
shelter them from any obnoxious influence.
Second, of an apparatus for straightening the wires for being laid down.
This apparatus consists mainly of a couple of rollers over which the wire is
passed, a third roller which is placed above and between said pair bending the
wire whilst it passes.
Third, of an apparatus for keeping the wires stretched whilst they are being
laid down and isolated. This apparatus consists mainly of a frame in which the
wires ends may be temporarily secured by wedges.
Fourth, of a comb between whose interstices the wires are made to pass so
as to keep them at an invariable distance; on this comb are fixed or hinged
bars or strips of metal, at right angles to the direction of the comb teeth,
and the wires being made to pass in the spaces left by the comb teeth, and
said bars are kept at an invariable distance both ways. I use these combs
and bars for casting or running the above-mentioned blocks or peices of
bituminous mastic in a continuous box or channel in intermittent lengths.
After the intermittent lengths have been cast between two combs, as described,
the bars on the combs are turned past the wires, and the comb may then be
withdrawn from between the wires and used further on. The box or casing
in which the running is performed on the spot may either be taken out or left
in the ground, and the vacant spaces between the different lengths run are
filled up with mastic, so as to form one continuous length of isolating bar.
Fifth, another means of holding the wire apart at the proper distances whilst
they are being cast upon; which means consist in diaphragms of various
shapes, which are made of isolating matters, or of the bituminous masticused
for the whole duct.
Sixth, of several new or improved means of testing the proper state of the
wires at suitable distances on the line of wires. I establish boxes made of
isolating matter, these boxes being sealed or shut in such manner that they
may be easily opened when it is desired to test the line of wires, which is
done by the usual means: the line of wires is made to pass bare through these
boxes over a testle or bridge of isolating matter, and for facilitating, peicing,
and connecting, I give each wire the form of a helical or coiled spring for a
short length. To preserve the wires from external influences, I sometimes also
partly fill the boxes with tallow, or other isolating matter that may easily be
taken out in the cold or solid state.
Another means consists in fixing stationery galvanometers at suitable
distances on the line of wires in the bituminous bar. These galvanometers

page_text: thus located are always ready for action, which may be taken up by placing a
magnet or magnetic needle in the cavity of the galvanometer. The galvano-
meters are placed either horizontally in the direction of the magnetic meridian,
or vertically, at right angles to said meridian, the latter arrangement allowing
the intensity of the galvanic current to be measured,
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Félix Marie Baudouin in the Great Seal Patent Office on
the 22nd June 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FÉLIX
MARIE BAUDOUIN, of Paris, in the Empire of France, and of 16, Castle
Street, Holborn (City), London, send greeting.
WHEREAS Her most Excellent. Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-second day of December, in the year of our
Lord One thousand eight hundred and fifty-four, in the eighteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Félix Marie Baudouin, Her special licence that I, the said Félix Marie
Baudouin, my executors, administrators, and assigns, or such others as I,
the said Félix Marie Baudouin, my executors, administrators, and assigns,
should at any time agree with, and no others, from time to time and at all
times thereafter during the term therein expressed, should and lawfully might
make, use, exercise, and vend, within the United Kingdom of Great Britain
and Ireland, the Channel Islands, and Isle of Man, an Invention for "Iм-
PROVED MEANS OF ISOLATING AND TESTING THE ISOLATION OF THE WIRES OF ELECTRIC
TELEGRAPHS," upon the condition (amongst others) that I, the said Félix Marie
Baudouin, by an instrument in writing under my hand and seal, should par-
ticularly describe and ascertain the nature of the said Invention, and in what
manuer the same was to be performed, and cause the same to be filed in
the Great Seal Patent Office within six calendar mouths next and imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Félix Marie Baudouin, do hereby declare
the nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:
This Invention relates to new or improved means for operating and make
lasting the insulation of the metallic wires of electric telegraphs, and to test
that insulation, which I will now fully and particularly describe.

page_text: First, I produce and make lasting the insulation of electric wires by using
asphaltum, bituminous and fatty substances ingeneral, not only using them as
a painting or coating merely, but still more especially by combining them with
other substances, in order to make insulating mastich for cementing with, and
puddings in which the wires are imbedded.
I am going first to describe the improved means by which I ensure the
insulation of electric wires, by using the substances mentioned above as a
coating or painting. I shall then proceed to set forth insulation with the help
of the same substances in the form of cements and puddings; and, lastly,
I shall explain the manner in which, under certain circumstances, those two
modes of insulation may be combined.
As to the insulation of the metallic wires by means of fatty substances in
the form of coating, the manner in which I operate varies, according to the
nature of the fatty substances used. For instance, some of those substances,
such as siccative oils and vanishes, are liable to form on the surface of the
wires a film, which having once acquired by dessication a proper consistency,
will preserve it, or not soften any more by heat. Hence these substances may
be used as a mere coating, and for that purpose the metallic wires that are
to be insulated, having been dried and cleaned properly, I cause them to pass
through a warm bath of fat varnish, similar, for instance, to the flexible
varnishes used in the manufacture of enamelled leathers, or oil skius or silk;
after the bath, each of those wires is made to pass through a draw plate, that
takes off the excess of the coating, and only leaves a thin regular layer. The
wires are thence made to pass through a long stove-like tube, in which a
current of hot air circulates, and this motion takes place in such manner that
the wires may remain in the stove a sufficient time to be dried, and the wires
upon leaving the tube may be coiled upon drums. This mode of coating
may be advantageously applied to thin wires for coils of electro-magnets, as
the insulating film is both very thin and pliable, and consequently the wire
may be coiled a great many times without producing a coil of too great
a thickness.
As to bitumens and other like fatty substances which are not liable to be
converted into a solid elastic body with a firm consistency, but according to
the temperature to which they are exposed, will pass from the solid to the
liquid state, and vice versa, it is obvious that a simple coating of said materials
laid on the surface of the metallic wires could not be a sufficient protection, on
account of this coating getting soft at comparatively low temperatures, and
being broughtout of shape and displaced under the slightest pressure. Instead
then of employing those materials alone, I use them conjointly with wrapping

page_text: materials that already act as insulators when dry, such as cotton, flax, hemp,
wool, or paper. For this purpose, I pass the metallic wire through a bath of
melted bituinen, having a temperature of 240 degrees Fahrenheit, about; on
leaving the bath, the wire is made to pass through a kind of draw-plate, in
order to take off the superfluous bitumen. A little farther on the wire is
wrapped in thread of cotton, or any other textile isolating substance, or in a
ribbon of some isolating fabric, or of paper. This wrapping is laid spirally on
the surface of the metallic wire by means of an apparatus similar to that used
by lace-makers, for covering with silk or cotton thread the thin metallic wires
for coils of electro-magnets, and for covering the cotton core of cord with silk.
Said apparatus, as is well known, consists of a disc secured on a hollow axis,
through which passes the core to be spun,over which, in this case, is a metallic
wire previously coated with a layer of bitumen. Said disc carries bobbins
with the cotton or other threads that are to form the wrapping, and turns upon
its axis, whilst the cord thread is receiving a rectilinear forward movement of
suitable speed; and as the thread is wound off the bobbins, it is made to form
on the metallic wire coated with bitumen a series of windings so close as to
cement with each other and with the surface of the metallic wire by the
viscosity of the bitumen. The metallic wire being thus wrapped, passes into
a second bath of bitumen, so as to receive there a second coating, that ought
to be smoothed well and sprinkled with powdered asphaltum, well dried and
finely sifted, in order to make the bitumen less pitchy. Moreover, I can, by
arranging several apparatus of this kind in succession, repeat the same opera-
tion several times, and thus cover the metallic wire by one process with
alternate layers of bitumen and cotton or other wrapping matter. Instead of
finishing with a layer of bitumen, the last layer may as well be of cotton or
even of paper, so as to prevent the wires thus prepared from sticking to each
other when they are coiled. By this mode of operating, the wrapping of
cotton or other textile matter which is placed round the metallic wires is com-
pletely sheltered from the influence of dampness by the bitumen that penetrates
it, takes away its hygrometrical character, and ensures a continuous coating,
which cannot be brought out of shape to any sensible degree, the textile
envelope resisting to any pressure the wires may be subjected to. Several
wires having been prepared in that manner, they may easily be united in a
bundle, and make by any of the known processes a sort of cordage with
lengthened spires, each strand of which is composed of a metallic wire covered
with one or several layers of bituminous coating or textile wrappings. I then
immerse this small cable into a bituminous bath, which may be thickened, if
required, with a mixture of asphalt powder, and I subject it to the operations

page_text: that have just been described forcoveringevery insulated wire separately, thus
covering said cable with alternate layers of bitumen and textile materials; and
in order to give it the more solidity, the operation may in certain cases be con-
cluded with a last covering of strong hemp thread, ribbon, or narrow banding of
sufficient thickness,and after that covering the whole, if necessary, with wire,
as is practised now for cables enclosing the submarine telegraph wires, in order
to preserve the system from all injury. The cable having been thus prepared,
& the last covering of hemp thread not having been coated with bitumen in
order to facilitate the handling of it, is rolled up on a barrel of a large
diameter, and thus is easily carried to the place where it is to be laid down.
By a process precisely similar to that described above, the cable may be dipped
into a last bituminous bath in order to cement the outer surface and to com-
plete the impermeability of the whole. The heat of this bath may also be
applied to soften the cable at the moment when it is laid on the ground, or
in the trench which is to receive it, and thus make it more pliable to suit
the sinuosities of the ground.
Instead of uniting the electric wires insulated by the ways I have just
described in round cables, I may form flat cables by placing the wires paralel
at a distance of one-half inch, about, from each other between two bands of
some fabric of suitable thickness, these fabrics being well impregnated with
bitumen, and binding the whole by longitudinal seams stitched between the
wires to be insulated, the sewing being done, for instance, with a well bitu-
minated hemp thread. The threads of these seams, whose stitches may be
rather wide, will insure the perfect insulation of the electric wires; also the
whole may subsequently be dipped into a bitumen bath, and covered with a
last coating of hemp thread, which is bituminated, if required. Again, in cer"
tain cases, instead of covering the electric wires or the cables formed by their
union with coils of bituminated thread or ribbon spires, I attain the same
object by placing them in a sort of sheaths, made of cotton or hemp bands,
or even of paper properly bituminated, and joining and soldering the edge
of these bands together, so that this wrapping will form a continuous tube of
bitumen and textile material, which firmly adhere to the surface of the wire,
and give a sound longitudinal joint; and to carry this principle into execution,
various mechanical means may be devised, like those used in different manu-
factures for covering with copper, iron or wood cylinders, as, for instance,
curtain poles.
The processes above set forth can be applied to wires already cemented with
gutta percha; they may be coated, for instance, either with a band of oil silk,
or an impervious cotton fabric, or paper with bituminated thread spires, or

page_text: merely with a layer of fatty varnish applied to the gutta percha, interposing,
when required, a very thin sizing, so that the varnish shall not dissolve the
gutta percha when applied on its surface, and then drying it by air or at a very
moderate heat; by these means the durability of isolated wires may be con-
siderably increased at a small expense. Also, instead of covering the gutta
percha with the above coating, I might commence coating the metallic wires
with varnish or bitumen that is capable bearing the temperature at which
gutta percha is worked; and thus, if gutta percha happen to slit or crack, as
is often the case, the wire is still preserved and insulated by the inside cement,
which prevents any possible communication through thesmall chinks between
the wire and conducting substances. Of all the fatty substances that may be
used to produce the results above stated, I prefer bitumens, and principally
natural Bastennes bitumens, or other such like, being both more consistent
and elastic, and less alterable. However, if required, other bitumens, or
combinations of tallow and bitumen may be applied over, or with resins and
resinous matters; and, finally, any combination of fatty substances, which,
whilst rendering the textile wrappings impervious, leave them their flexibility,
and, above all, are not decomposed by the influence of electric currents.
Second, I also obtain insulation of the telegraphic wires by means of fatty
bodies, and particularly bitumens mixed with other materials, in the form of
mastich or pudding stones. The composition of bituminous mastich and
pudding stones used for coping and flagging, &, is well known, therefore,
I will only say that among these different mastiches or puddings I prefer
those made of natural asphaltic calcareous powder and natural Bastennes
bitumen, as being both more solid and supple than any other kind. With
these cements I form either blocks or pieces, similar to kennel stones, with
multiple compartments or tubular ducts, which may be soldered together or
not, and in which the wires are completely separated from each other; or I
run those cements on the spot, between the wires kept at the proper distance,
into longitudinal troughs, so as to form, after cooling, solid blocks or continuous
pieces, in which the wires are buried or imbedded, so as to fix and shelter thein
from any obnoxious influence.
The first way of forming kennel stone blocks with multiple compartments
is shewn at Fig. 1, which represents a fiat kennel-stone block, divided by
longitudinal partitions into a certain number of grooves or small kennels, six,
for instance.
Those kennels may be made beforehand in lengths of 4 feet 6 inches, about,
and then placed end to end in the trench, joining them with hot bitumen ;
they may also be made in the trench itself without any solution of continuity,

page_text: by running between rulers 14 inches high a bar of bitumen about one inch
wide, and forming in it, whilst the substance is yet hot, grooves of about of
an inch deep, by means of an iron or wooden grate, the longitudinal bars of
which by sinking into the bitumen will hollow out the grooves wanted. For
this purpose, a to and fro motion is given to said grate, till the
grooves have
assumed their form and hardened enough to keep it. The wires, being thus
placed in the grooves of this long kennel, are covered with bitumen plates,
soldered to each other and also to the kennel with very hot bituminous cement,
taking care also to avoid or make good any splitting or rupture, so as to pre-
veut any communication being established between the inside part and the
ground. In this manner, if it is desired to lay the wires bare at any part of
the line, this can be done by cutting with a hot iron the cement of the joints
of the lid, and replacing that lid carefully in the manner above described.
Various modes mayalso be employed forproducing these long grooved kennels;
for instance, the operation may be inverted by running in the trench a bar of
bitumen of 20 inches wide, about, letting it cool, and running on each edge a
small ledge of hot bitumen, and then apply upon it in a reverse position the
kennels described above, & made beforehand; these kennels thus forming a
grooved lid, the partitions of which will rest upon the bitumen ground, and
virtually separate the metallic wires. By this arrangement, the lids will offer
a greater solidity on account of their longitudinal partitions, which will form
as many ribs.
Figure 2 shews a transverse section of a duct made according to my system,
for 12 wires. It consists, as may be seen, of a long block, perforated with 12
cylindrical and parallel holes, separated by thin partitions, and which present
greatsolidity under a small bulk. These ducts are made in the following new
or improved way :-
Suppose Figs. 3 and 4 to represent a mould of cast iron, or of any other
material of sufficient resistance, having the same form (but inverted) as the
hollow block to be produced: the cheeks of the mould are perforated with
as many circular holes as there are wires to be put in; twelve, for instance.
The holes of the two cheeks are quite opposite each other, so as to have the
same axis. Through those holes I pass iron tubes whose bore is a little larger
than the gauge of the wire, and the external surface of which is well turned and
smooth, beginning with the tubes that form the lower row. Into this mould
I cast a bituminous cement, which is very thick without being brittle, taking
care to have it run beneath the tubes and through the interstices that sepa-
rate them. The first row of tubes having thus been flushed, the second row of
tubes are put in and embedded in a second layer of the same hot cement, then

page_text: the third rank of tubes is introduced, and the mould is filled up; care must be
taken to compress the bitumen well without bending the tubes. In order to
hasten the cooling, and allow soon to take the casting from the mould, the
mould thus filled with bituminous cement may be plunged into a trough filled
with water, or rather in which is poured a stream of cold water. When the
bitumen is cooled, the iron tubes are withdrawn in the following manner :-
The bitumen by cooling having shrunk round the iron tubes, to which it
remains strongly adherent, to loosen them again I introduce into each of them
a red-hot iron rod which fits easily into the tubes; by this contact the
bitumen close to the tube will soon be melted. The tube is then turned &
moved to and fro, in order to detach it from the bitumen, and after having
withdrawn the iron rod, 1 introduce in its stead a streamlet of cold water,
which makes the bitumen solid again; and still going on moving and turning
the tubes, the bitumen is smoothed as it gets hard, and thus a perfectly
level, straight, and smooth tube is obtained. The same operation is performed
with every hollow iron tube, and when all are taken out of the block, it will
form a parallel set of tubular ducts. The work just described may be done by
hand, or else by machinery moved by steam, if required. The tubular ducts
being made all alike, and of any suitable length, are laid down in the trench
end to end, at a distance of 2 inches, about, ou a layer of mortar, or even of
sand. In order to join them, we introduce in the holes of two consecutive
ducts small hollow tubes, of any insulating substance, such as porcelain, glass,
terra cotta, sandstone, wood, bone, or even bitumen, or bituminated paper, &".
In order that the said small tubes, which are to have internally the same dia-
meter as the tubes of the bars of asphaltum, which they are to continue and to
join, may easily be introduced, I widen the tubes out, as shown in Fig. 5. The
ferrels or connecting tubes having been inserted, I cast between the different
prisms a mass of very hot bitumen, that is supported by lateral bands of the
saine form as the prisms themselves that are thus perfectly soldered together.
When a sufficient length of duct has thus been obtained, I pass through every
one of the holes of the prisms a metallic wire, which is either bare or already
wrapped in an insulating substance, such as cotton, flax, hemp, rope, &c., as
has been described herein-before. The wire may also be inserted before
imbedding in bitumen the small joining tubes, so that by displacing the latter,
if required, the introduction of the wires may be facilitated, for which purpose
the ends of the wires may also carry either a little ball or a small pully, which
diminishes the rubbing, and prevents the sharp end of the wire from injuring
the bitumen or scraping it. A second part of duct is laid down in the same
manner after the first, leaving between them space enough for soldering the

page_text: wires together. I then join these parts of duct together by means of bitumen,
thus going on till the whole duct is finished.
The third way of insulating the electric wires consists in imbedding them
hot into blocks of asphaltum, which, completely covering them on all sides,
forms one body with them, and ensures their perfect insulation. Nothing
seems plainer at first than casting thus bituminous cement round a certain
number of wires, contained, for instance, in a small wood case, and the modus
operandi that first occurred to me was as follows:-The wires were held by
one end, and placing them in a proper order, Istretched them and maintained
them thus stretched at a suitable distance from each other by means of a rack,
or any other apparatus, that was drawn forward as the bitumen was cast; but
this mode, which would be very good if the wires were to be imbedded in a
plastic substance, assuming directly consistency enough not to allow the wires
to be displaced or bent, does not suit bituminous cement, which, especially
when used in a large bulk, is liable to preserve its heat and fluidity a long
time. By the effect of this great heat of bitumen, metallic wires will expand,
bend, and be displaced so that even when the wires are separated by 2inches,
about, which is a considerable distance, and makes the ducts very bulky, the
wires are likely to touch one another, and sometimes to come out of the bitu-
men, without any possibility of ascertaining the position of the wires inside the
bitumen. Ihave, therefore, devised the following arrangements and apparatus
for keeping the wires straight, and maintain them in their respective places, not
only during the time the bitumen is cast, but also until it acquires by cooling
solidity enough to be safe from any displacement whatever. First, for strong
wire, which is hard to stretch and straighten, I use an apparatus shewn on the
annexed Sheet of Drawings at Figs. 6 and 7. This apparatus consists in
a couple of grooved rollers, over which passes the wire to be made straight, a
third roller that is placed over and between the two others bears upon the wire
as it passes, and straightens it by taking the small bends out. In order to
hold the wires at the beginning and at fixed distances, and maintain them
stretched, I use the apparatus shown at Figs. 8 and 9. This apparatus con-
sists of a kind of frame with vertical grooves, resembling inverteed steps; these
grooves being intended to receive two rows of metallic wires, which are held fast
in said grooves by tightening wedges, in the manner described herein-after.
The wires being stretched in the ditch between the boards or ribs that are
laterally to limit the block of bitumen between and round them, I use, in order
to maintain their distance, cast-iron combs or racks, as shown at Figs. 10 and
11. On those racks are fixed hinged bars, or strips of metal having the form
of shutters, placed at right angles to the direction of the teeth of the combs,

page_text: and intended to be placed beneath every row of the wires they are to separate,
thus maintaining them in a fixed position.
The way I use those different apparatus is as follows:- In order to establish,
for instance, a telegraphic line of eight wires in two rows, one above the other,
every one of the four wires is placed one inch distance from the next, both
above or under and by the side of it; after making the trench in which the
telegraphic line is to be laid, I tie up the eight wires on a solid fixed point;
I unroll and stretch them on a certain length, twenty yards, for instance ; I
then stretch them, one by one, by means of a jaw with a set screw, this jaw
being secured to a pulley block that should not be fixed at more than one
hundred yards from the above said starting place. In case some wires cannot
easily be straightened, I stretch them by means of the little apparatus shown
at Figs. 6 and 7. The wire being stretched, I maintain its tightness by means
of the apparatus shown at Figures 8 and 9. Thus, the first wire being
stretched, I insert it into the first groove of my apparatus, and bring it to the
bottom of the small groove C. I then drive in the wedge K, keeping the same
in a fixed position, and their the same is done for the three other wires of
the first row, which are thus fixed at C₁,C", C. It will be observed that the
upper parts of the wedges K, K1, K", K, have little grooves Civ, Cv, Cvi, Cvii,
in which the 5th, 6th, 7th, and 8th wires, forming the upper row, are laid; they
are kept in that position by other fastening wedges Kiv, K, K, Kii, that are
driven into the corresponding empty spaces. This operation is renewed at
each of the extreme ends of the wires, and even at one or two intermediate
points, by means of as many small apparatus, similar to the first. This being
done, I pass or glide under the wires a paper casing, prepared beforehand, the
bottom of which touches the ground, that has previously been prepared and
covered with a layer of dry sand; the edges of the said paper casing are then
turned up and fixed with little nails on wood ribs, about 3 inches across, and
placed at a distance of about 6 inches, so as to form between the said rulers
laid on the ground a channel lined with paper 6 inches wide and 3 inches
deep. The purpose of this paper lining is, first, to prevent the bitumen from
sticking to the wooden rulers; and, second, to prevent the sand from entering
the bitumen when it is run and pressed between the ribs, and thus causing
ruptures in the bituminous duct. Instead of using paper for lining, I some-
times employ coarse linen that has first been rendered impervious, and which
uniting with the bitumen adds to the perfect insulation of the wires and the
solidity of the duct. This arrangement is shewn at Figs. 10, 11, and 12.
This channel being thus prepared, I place at about 10 inches distance from
one another the cast-iron combs, described above, and represented at Figs. 10

page_text: and 11, and also at Figs. 12, 13, and 14, which show the arrangement of the
rulers, the wires, and combs, and also the successive castings of bitumen. The
wires being inserted in the comb, the two hinged bars, above described, are put
to, so as to separate the two rows of wires, and sustain and hold them at the
proper height, each wire being supported both vertically and horizontally in
its proper position. The combs are placed in pairs, in such a manner as to
have their hinged bars facing each other, and so that they are turned towards
the interval they are forming; thus the bars are contained in the odd intervals
1, 3, 5, &, and the even (2, 4, 6, &*.) intervals are limited by combs, the
interior frontof which has no bars, and is altogether even. The combs being
thus placed, I run into the even intervals very hot bituminous cement mixed
with a sufficient quantity of dry sand. It is evident that all the wires being
thus supported from comb to comb cannot be sensibly displaced in such short
lengths. The whole length of wires being thus imbedded, the bitumen is left
to cool, and as the cast-iron combs or diaphragms have a certain bulk, the
bitumen in contact with them is cooled by the metal of said combs, and thus
solidifies, adhering but little to them. When the cooling is far advanced
enough that there be no more danger for the bitumen to be brought out of
shape, the combs are detached from it by knocking, and the hinged bars are
turned into the perpendicular position to the surface of the combs, allowing
them to be lifted out. Thus we have in the even intervals a series of small
bituminous blocks 10 inches wide, in which the wires are regularly and firmly
imbedded at about one inch distance from one another. The odd intervals, on
the contrary, form empty spaces, in which eight wires are left bare for a length
of only 10 inches, but these wires, having their extremities firmly fixed into
the small contiguous blocks, are sufficiently stiff for imbedding them in bitumen
without causing any sensible displacement of the wires. The single blocks are
thus joined into one continuous length of great rigidity, and the wires being
pieced or soldered, as many of these lengths may be successively laid down as
will suffice for the line of telegraph between the two stations which it is
desired to connect.
Instead of using cast-iron combs, like those above described, the wires may
be kept at regular distances by means of bitumen guides or supports that are
grooved and ready made, or else by means of diaphragms of the same, or any
other insulating substance, pierced through with holes, in which the wires are
made to pass. In case these guides, supports, or diaphragms are made of
bitumen, it will be found necessary to give them a sufficient bulk, so that they
shall not soften too much under the influence of the heat of bitumen run into
the channel, nor give way to the twisting tendency of the wires. Figures 15

page_text: to 22 represent different arrangements of guides, supports, or diaphragms
of bitumen. In all cases, and even when those guides or diaphragms should
be of an insulating substance, that is, not liable to be softened by hot bitumen,
as, for instance, porcelain, sandstone, terra cotta, &c., it will still be necessary
to place from distance to distance, whilst the mass of bitumen is cast, heavy
stops or impediments, that may resist the expansion, and prevent the displace-
ment of the wires, such as strong bars of cast or wrought iron; these bars
being sufficiently thick to project above the superior level of the duct, in order
to prevent the guides being displaced; these bars being taken away when the
bitumen is cold, and the interstices filled up with very hot bitumen. The
hinged bars on the combs above described may also be dispensed with by using
only plain combs to maintain the wires in their positions vertically. To main-
tain them horizontally, I should use small iron or cast-iron bars, acting as
supports, and being carried along by a rod, which facilitates the handling of
them, as shown at Figures 23, 24, and 25. These wood or cast-iron supports
may also be substituted by bitumen bars or blocks, to be introduced under the
first row of wires, and between the two rows. The said bitumen bars or
supports might be left in and embodied with the mass of the bitumen cast
afterwards, for the purpose of blocking the wires. From the preceding
description, it will be obvious that the modes of maintaining the wires in
the bitumen till the same has cooled may be varied in many ways without
departing from the principle of this improvement, which consists in imbedding
any number of electric wires in a bar or block of bitumen, said wires being
keptasunder at the proper distances by means of blocks, bars, guides, supports,
or diaphragms of any kind to prevent the displacement of the wires in hot
bitumen, and consequently ensure their perfect insulation from each other
and the ground itself. These guides, supports,&c. may be made of any suitable
substance, provided that substance beinsulating, if they are to remain imbedded
in the bitumen; or in case they are of cast iron or other conducting substance,
they are so contrived as to be easily lifted out or removed, the empty spaces
left between them being afterwards filled up with bitumen, that perfectlyunites
with that already cast.
I shall conclude these remarks by stating that the first way of insulation
of the electric wires, viz., by wrapping in textile envelopes and alternately
applying a bituminous coating, and also the mode of coating with gutta percha
only, may be usefully combined with that we have just described, by wrapping
and bituminating the wire before stretching and imbedding them in the
trench; also, by uniting into a small cable several wires covered with cotton
and bituinenated cotton. The insulation of that cable may still better be pre-

page_text: served by imbedding it in bituminous cement, that may be run either in a
long sheath of wood, bituminated paper, or any fabric, which this sheath
when passing through railway tunnels, being fastened to the side walls of
the tunnel, or in a channel made in the masonry, or else laid down in a
trench on the ground. Instead of the bituminous cement above mentioned,
asphaltum may also be employed in the powdered state, by heating the same
and pouring it over the wires, when it will unite and form an impervious
insulating mass.
As to the improved means of testing the proper state of the wires for the
purpose of finding out the point of wire where insulation may have become
impaired, I effect this by leaving at suitable distances openings for enabling
the operator to cut the wires, either for the purpose of making experiments, or
for coupling the wires in various ways. These openings consist either of cast-
iron boxes, the inside of which is lined with bitumen, or else of pits walled up
with masonry or bricks, covered with a continuous coating of bitumen in the
inside. The bitumen block or course, in which the wires are imbedded, joins
the box or pit, and all the wires cross the same, it being filled with melted
tallow, or any other anti-hygrometric insulating substance, which can easily be
taken out when cold. The pit or opening is then covered again with a lid of
bitumen, or lined with the same, and this lid is luted on the pit by means
of hot bitumen, so as to keep out any dampness, and completely insulate the
wires. Also, in order to insulate them from one another, they are kept
asunder, by means of small partitions or trestles of bitumen, or any other
insulating substance, the same as those represented at Fig. 26. In order to
facilitate also the coupling up of the different wires in said testing boxes
or pits, each wire is coiled, so as to form spires of a suitable length at
their entering and leaving the box, as shewn in section of one of the pits,
Fig. 26. For facilitating the operations, the wires may be soldered with any
of the known fusible alloys. I also cover the wire whilst it passes through
the opening with a wrapping of bituminated fabric, which also extends overthe
soldered part. The main boxes or pits just described are placed at pretty
great distances, and at such points where the line is likely to be cut; but
smaller ones of a less expensive construction may be placed at intermediate
distances, thus affording the means of easily determining between what points
the contact between wires, communications with the earth, and any breakage
exists. For this purpose, each wire is cut at fixed distances, and the two ends
are connected by means of a galvanometer, which is made as follows:-A
metallic non-magnetic blade, or a wire of the same kind and covered with an
insulating substance, is coiled up a suitable number of times round a frame of a

page_text: galvanometer, and the whole is buried in the bitumen, so as to form a mass
of the shape shown at Figs. 27 and 28. The shaded part represents the
small bitumen block that contains the frame of the galvanometer, and into
which the coiled wire is imbedded. The unshaded part represents the opening
of the frame of the galvanometer, which is empty. This frame is fixed to the
block of bitumen, that contains the wires of the line by a bituminous cement,
so as not to have any communication with the ground or external influence.
There are as many galvanometers required as there are wires in the line.
The frame of the galvanometer can besides be laid in two different ways,
according to which the apparatus is differently arranged; viz.,it may either be
laid in such manner that the plane A, B, C, D, of the frame be vertical, as at
Fig. 27, or that said plane be horizontal, as at Fig. 30.
In the first case, care must be taken before soldering the galvanometer to
the bitumen of the line to set it in such manner that the plane A, B, C, D,
coincides with that of the magnetic meridian. The frame being thus set, if it
is desired to measure the current coming from a wire of the line and passing
through the corresponding wire of the galvanometer, a copper plate E, F, is
introduced into the opening of the latter, this plate being laid horizontally by
means of four stops R, R, RU, RI, which fit on the vertical inner sides of
the galvanometer. At the centre of said plate there is a magnetic needle
N, S, moving on a pivot connected at right angles to a non-magnetic needle
L, the deviations of which as the current passes, and consequently those of
the magnetic needle, can be read by means of divisions engraved on the plate
(see Fig. 29).
In the second case, in which the plane A, B, C, D, of the frame of the
galvanometer is laid horizontally (Fig. 30), the open part of the said frame
must not be set in the plane of the magnetic meridian, but perpendicularly
to it, and then, instead of a magnetic needle carried by a vertical pivot, I get
a similar needle N, S, laid horizontally, but supported by a horizontal knife
L, T, the edge of which will bear on two portions of a cylinder of agate, or
any other hard substance, which is fixed on the two sides of a strap E, placed in
the open part of the galvanometer, see Figs. 30, 31, 32, and 33. This needle
is secured at right angles to an index hand H, P, bearing at its extremity a
small counterweight P, intended to bring the magnetic needle back to its
horizontal position, and to counterbalance the effort of the electric current,
which tends to deviate it, and hence to measure the power of that current.
The index hand H, P, Fig. 33, is also secured, but not fixedly, to the magnetic
one N, S, by means of a small axis 0, on which the indicator needle may be
turned with stiff friction. By this arrrangement the needle is made to give an

page_text: exact measure of the electric current; in fact, the apparatus being set in
such manner, that the magnetic needle N, S, be in the horizontal position, and
the index hand H, P, placed vertically, if there be no current the apparatus
will keep in the same position; but if a current be made to pass through the
wire coiled round the frame of the galvanometer, the magnetic needle N, S, is
deviated towards N¹, S¹, and raised on one side, (north, for instance.) In
consequence of this movement, the needle indicator H, P, will also be deviated
from the vertical line into the position H1, P1, and that deviation will cease
the moment the action of the small counterpoise P1,it bears at its lower end,
will have become equal in force to the electric current. This action is
measured by multiplying the small weight P by the distance P, O, between its
centre of gravity and the centre of rotation, and by the sine of the angle a,
through which the needle H, P, has deviated from the perpendicular. This
action is also an unknown function of the intensity of the current ; but, if by
trying at random, the index hand is turned in the direction of its deviation, it
is evident that the small weight P will act more powerfully to bring back the
magnetic needle to the horizontal position, and a position will be arrived at in
which the index hand cannot be brought back to the vertical position when
the action of the small weight equals that of the electric current on the
magnetic needle. But the action of the little weight in that new position
will still be represented by multiplying the weight P by the distance P, O,
and by the sine of the angle a, made by the directing needle with the per-
pendicular; but, as in this product P and P, O, are constants, and there is no
variable quantity but the sine of the angle of deviation, it follows that the
action of the small weight P, or the action of the electric current, which it is
equivalent to, is proportional to the sine of the angle of deviation. The angle
may easily be read off by applying a common protractor to the system of two
needles. The following is the way in which this apparatus may be used for
finding out the points where there may be communications with the carth,
contact between the wires, or ruptures. Supposing it is desired to ascertain
where one of the wires communicates with the earth this wire is connected
at the starting station with the battery, and at the other station is insulated.
If the wire is in communication with the earth at one or several points, the
current from the pile will be lost at those points. Hence all the small appa-
ratus just described will indicate a current when they are between the battery
and said points, and those placed on the other side will remain inactive, or
only indicate a weaker current. Hence, if, after an apparatus indicating the
current, the next after that remains inactive, or nearly so, this shews that
there is a rupture between the two apparatus. Should the wire tested be in

page_text: communication with the earth at many places, this will be shewn by the
current, as indicated by said apparatus, diminishing after every point of contact.
For discovering the contact between the wires, the same manner may be
adopted, only the two poles of the battery will have to be put in communica-
tion each with one of the two wires that are supposed to be in contact, whilst
said two wires are accurately insulated at the other end; also, if it is supposed
that the wires are broken, the place is found out by successively looking
through all the apparatus connecting one of the poles of the battery to the
wire and the other to the earth, and taking care to uncover the wire a little
after the galvanometric apparatus, so as to bring this point into contact with
the ground. When, after testing the insulation of a portion of line-situated
between two apparatus, the current is found to stop between the apparatus
last tried and the next, it may be depended upon that the rupture is between
the two points last mentioned. The laying bare of the wire is very easily
effected, since, in order to be connected with its galvanometer, this wire must
have passed over all the other. Having thus laid the wire bare, the thin
layer of bitumen that covers it is taken off, and insulation is re-established by
applying some bitumen on this point with a hot iron. It will be observed
that the small galvanometric apparatus above described are fixtures ou the
ground, there being no moveable part but the plate or the strap carrying
the needles, which plate or strap is laid in the open space of every galvano
meter when an experiment is to be made to be taken out afterwards. This
open space is preserved in the ground by a stopper or filling piece, or even
bitumen, that is put in again after the testing experiment is concluded, in order
to prevent the earth from filling the cavity. I wish it to be understood that
this method of testing the metallic wire by means of smail fixed galvanometers
may also be advantageously applied to line wires supported in the air or to
ordinary telegraphic lines.
Independently of the principal openings, boxes, or pits, and the smaller
openings or pits with galvanometers that are merely laid in the ground, the
line may also be tested by operating as follows:-The line of wires is laid bare
at any point of the trench, the wire to be experimented upon is uncoated and
cut, so that the wire of a galvanometer may be put in, and thus all the known
operations are performed for ascertaining as usual the place where the galvanic
circuit is out of order. The wire is most conveniently laid bare by pouring
hot bitumen upon the prism or bar in which they are imbedded, thus softening
it, when it may be cut, and the testing experiment made; the gap thus made
made be filled up again by running hot bitumen between proper wood ribs, as
above described.
:

page_text: The following is a description of the Figs. on the two annexed Sheets of
Drawings partly alluded to in the above statement :-
Fig. 1, section of kennel block, with multiple compartments; c, under
block; c, lid; r, ridges; e, grooves.
Fig 2. transverse section of a block with tubular ducts t.
Fig. 3, perspective view of mould for running the blocks.
Fig. 4, longitudinal section of the cast-iron mould, with its three rows of
iron tubes 'T, T.
Fig. 5, section of two adjoining blocks, with unions C, C.
Fig. 6&7, longitudinal and cross section of the apparatus for straightening
the wire. A, A, axis of rollers; B, cross stay; C, C, handles for carrying;
G, G¹, G, grooved rollers or pulleys, between which the wire is made to pass;
J, J, bars in which the lower rollers turn; J1, J1, bars for the upper roller G
to turn in; K, K¹, wedges for forcing the upper bar J, J', down; M, M',
mortices; T, T, uprights for the upper bar to slide upon, this bar being guided
by rebates t, t'.
Figs. 8 and 9, elevation and cross section of the wire-holding apparatus.
R, R¹, R, R, groves or slots, widening out stepwise; C, round notches for
receiving the wires; K, K, K, under row of wedges for tightening the wires
against the frame; C, grooves on the top of these wedges for pressing the
wires against the upperwedges K1;0, hooks or holdfast for fixing the apparatus
to the ground.
Fig. 10, elevation of an 8-wire comb; Fig. 11, end view of the same.
Fig. 12 (Sheet 2) plan of an 8-wire duct turning a sharp angle; Figs. 13
and 14, side and end view of the same. A, point where the wires are attached;
ffff, metallic wires; B, wood ribs wrapped in paper; P, combs with
hinged bars C, C; P, P, large combs for turus; D, D1, teeth of the combs;
R, R, spaces; K, holding apparatus (see Fig. 6); P. P, paper. No. 1, open
interval; No. 2, interval into which bitumen has been cast.
Figs. 15 to 22 (Sheet 1) shew various single and double guides, supports,
or diaphragms of bitumen for 5 and 9 wires respectively.
Figs. 23 and 24 (Sheet 2) shew a stay for holding the wires apart when the
combs used are without hinged bars C, C¹; and Fig. 25 shews a line in course
of being laid down in this manner.
Fig. 26, Sheet 2, section of a testing box or pit; N, level of ground; T,
ground under the bituminous duct B; f, f, wires, coiled spires; M, side walls
of bricks; e, coating of bitumen; D, bottom of bitumen; F, concrete founda-
tion; R, wire supports or bridges of bitumen; C, cast-iron lid imbedded in
the bitumen; S, bituminous luting or cementing.

page_text: rigs. 27 and 20, vertical galvanometer frame. A, D, G, D, porcelain frame
upon which the wire is coiled a great number of times; only one-half of the
wire is shewn in the Figures.
Fig. 29, needle plate E, F. R, R¹, R1, R, studs for fixing the plate
upon the galvanometer; N, S, magnetic needle; H, L, index hand; d, d, d,
divided arc.
Fig. 30, horizontal galvanometer, placed perpendicular to the magnetic
meridian.
Fig. 31 shews the position of the needle-carrying strap, Fig. 30.
Fig. 32 is a detached view of this strap. 1, 2', cylindrical supports; o, axis ;
L, T, knife edge.
Fig. 33 shews the magnetic needle so fixed upon the axis as to be in a
horizontal position. H, P, non-magnetic needle movable upon the axis o; P,
weight at the end of the needle H, P; H¹, P, and N1, S1, positions of the
needles when deviation takes place by a current; H", P, position to begiven
to the needle H, P, so that the counterweight shall bring the magnetic needle
back to the horizontal position by counterbalancing the deviating current.
I claim, first, the method of insulating telegraphic wires by means of fatty
varnishes and bitumens to be used as coating, especially by applying alternate
layers of said coating and of a fibrous matter, substantially as above described.
Second, the method of insulating said wires by means of bitumen, used
either as cements or puddings, which are solidified by cooling, or by working it
into multi-tubular blocks or kennel-like pieces, in which the wires are inserted,
but not fixed, or else by running it in blocks or courses in which the wires are
buried or imbedded, substantially as described.
Third, the method of combining the first method of insulation with any other
means, or with the second method.
Fourth, the apparatus for straightening and stretching thewires,substantially
as described and shewn on the annexed Drawings.
Fifth, the use of stops, guides, or combs with cross hinged or other pieces,
or their equivalents, for holding the wires apart till the bitumen has solidified,
said combs being then withdrawn ; also of guides, diaphragms, or supports
made of bitumen or other insulating substance, these guides, &c. being left
in the course or block of bitumen run over and between them,substantially as
described.
Sixth, the mode of testing the wires by means of openings, boxes, or pits
constructed in such manner as to insulate the wire passing through them, and
of galvanometers which are connected to the line wires, and placed at regular
distances in said boxes or on the telegraphic line, a magnetic needle being

page_text: so placed in the opening of the galvanometer as to indicate not only the
existence or cessation of the current, but also to measure its intensity.
In witness whereof, I, the said Felix Marie Baudouin, have hereunto
set my hand and seal, this 18th day of June, One thousand eight
hundred and fifty-five.
F. M. BAUDOUIN. (L.S.)