IMPROVEMENTS IN IRON TELEGRAPH POLES
Year: 1874

page_text: LETTERS PATENT to John Muirhead, junior, of Stanley Villa, Thornton
Hill, Wimbledon, in the County of Surrey, for the Invention of
"IMPROVEMENTS IN IRON TELEGRAPH POLES."
Sealed the 11th December 1874, and dated the 15th June 1874.

page_text: With these objects in view I construct telegraph posts in the manner.
shewn in the annexed Drawing.
In a light socket of cast iron of the form shewn and weighing about
56 pounds I insert a compound tube of very thin wrought iron, No. 11
gauge, welded up upon a liner of steel or iron of the same thickness, and 5
extending for three feet up the tube. This portion of the tube is
parallel, whilst the remainder of its length tapers from an external
diameter of three inches down to a diameter of two inches. Into the
upper end of the tube an iron plug is welded; it has a hole in the centre
which is tapped to receive a corresponding screw on the stem of the 1
insulator.
°
If a wire guard and lightning discharger be required they are formed.
together and are secured by means of the insulator stem, which is passed
through an eye or eyes in the wire guard before it is screwed into its
socket, and when the stem is screwed home the wire guard becomes
clamped between a collar on the stem and the top of the plug which
closes the end of the post.
The total weight of the post, as shewn, is about one hundredweight,
which is much less than the weight of any post of equal strength hitherto
produced, and this advantage is obtained without any addition to the
cost of production.
When the post is required to support more than one wire I carry such
additional wires by means of malleable cast-iron brackets. Each bracket
consists of a central boss fitting on to the post, and fixed by keys driven
in grooves formed within the boss. Cast with the boss and on opposite
sides of it are two arms with sockets at their ends to receive the stems
of the insulators. The arms on the two sides are inclined, the one
upwards and the other downwards, so that when the wires swing with
the wind, they may not come into contact the one with the other.
Sometimes I flatten the tubular post into an oval form to increase its
strength in the direction in which the strain of the wire comes upon it;
a corresponding alteration is then made in the form of the upper part of
the cast-iron socket.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Muirhead in the Great Seal Patent Office on
the 15th December 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
MUIRHEAD, junior, of Stanley Villa, Thornton Hill, Wimbledon, in the
County of Surrey, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifteenth day of June, in the year of
our Lord One thousand eight hundred and seventy-four, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Muirhead, Her special license
that I, the said John Muirhead, my executors, administrators, and
assigns, or such others as I, the said John Muirhead, 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, tho
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS
IN IRON TELEGRAPH POLES," upon the condition (amongst others) that
I, the said John Muirhead, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and
scals, should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said John Muirhead, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say :-
This Invention has for its object improvements in iron telegraph
poles.
Iron telegraph poles are very often employed in places where transport
is difficult and expensive; it is consequently of very great importance to
make them as light as is consistent with sufficient strength and durability.
With these objects in view I construct telegraph posts with a foot or

page_text: base of cast iron, and with the upper part of wrought iron or steel. The
upper part is made hollow, its foot is made to enter within a socket in
the cast-iron base, and at this part (its weakest point) it is strengthened
by doubling or thickening the metal.
Having thus stated the nature of my Invention, I will proceed with
the aid of the Drawings annexed to describe more fully the manner of
performing the same.
In a light socket of cast iron of the form shewn, see Figures 1, and
weighing for a pole 18 feet high about 56 pounds, I insert a compound
tube of very thin wrought iron, No. 11 guage, welded up upon a liner of
steel or iron of the same thickness, and extending for three feet up the
tube. This portion of the tube is parallel, whilst the remainder of its
length tapers from an external diameter of three inches down to a
diameter of two inches. The way this may be done is as follows:-The
liner is first made like an ordinary tube, being welded up by drawing
through tongs, and is cut off to the lengths required. The parallel
portion of the outer tube of which the pole is formed is welded up in a
similar way, and the liner is inserted within it just before it is passed
through the welding tongs; it is not necessary that the liner should be
heated. The taper part of the pole is welded by means of a series
of tongs of different sizes. The strength may be further increased by
inserting a diaphragm or diaphragms within the liner before it is
welded up.
The diaphragms may either be of cast iron or sheet metal discs stamped
so as to raise a cylindrical flange around the edge, and in welding up the
liner tube the metal is closed down on to the flanges of the diaphragms.
The diaphragms keep the tube in form during severe strain, and prevent
the pole failing by collapse.
The pole tube itself may be strengthened by diaphragms in a similar
manner where a liner is not employed.
Where poles are made in lengths socketed together, as is done in some
cases, diaphragms may advantageously be inserted near the ends of the
sections. Into the upper end of the pole an iron plug is inserted
and secured in welding up the tube; the plug has a hole in the centre,
which is tapped to receive a corresponding screw on the stem of the
insulator.

page_text: If a wire guard and lightning discharger be required they are formed
together and are secured by means of the insulator stem, which is
passed through an eye or eyes in the wire guard before it is screwed
into its socket, and when the stem is screwed home the wire guard
becomes clamped between a collar on the stem and the top of the plug
which closes the end of the post. Figure 2 shews the arrangement of
these parts.
The total weight of the post, as shewn, is about one hundredweight,
which is much less than the weight of any post of equal strength hitherto
produced, and this advantage is obtained without any addition to the
cost of production.
I would remark that the sizes and weights herein stated may be varied
without departing from my Invention.
When the post is required to support more than one wire I carry such
additional wires by means of malleable cast-iron brackets. Each bracket
consists of a central boss fitting on to the post, and fixed by keys-driven
in grooves formed within the boss. Cast with the boss and on opposite
sides of it are two arms with sockets at their ends to receive the stems
of the insulators. The arms on the two sides are inclined, the one
upwards and the other downwards, so that when the wires swing with
the wind they may not come into contact the one with the other.
Figure 3 shews the arrangement of these parts.
Sometimes I make the tubular post of an oval form to increase its
strength in the direction in which the strain of the wire comes upon it;
a corresponding alteration is then made in the form of the upper part of
the cast-iron socket.
The oval shape may be extended from end to end of the pole, or
may be confined to the lower portion; it is produced, by preference, by
the use of tongs of corresponding form in the process of welding up the
tube.
The diameters of the oval tube may conveniently bear to each other
the ratio of three to two.
Although I usually prefer to double the thickness at the lower part
of the pole by inserting a liner, nevertheless the additional thickness
may be applied externally as a jacket, in the manner indicated in
Figures 4.

page_text: If desired, two or more liners or jacketing pieces one over the other
may be employed; they should be of different lengths, or the metal may
be rolled or otherwise formed so as to be thickest in the position required,
according as the strain is distributed throughout the pole.
I coat the poles to protect them from oxidation by heating them
and dipping them into a composition of tar and fine sand or powdered
silica. The coating of composition hardens upon the post as it cools.
.
Having thus described the nature of my said Invention, and the
manner of performing the same, I would have it understood that I
claim,―
1st. The construction of telegraph poles substantially as described.
2nd. The means of strengthening telegraph poles, consisting of tubes
of wrought iron or steel inserted into cast-iron sockets, by thickening
the metal at the lower end of the wrought iron or steel pole tube
according as the strain is distributed along the pole, substantially as 1
described.
3rd. The means of strengthening telegraph poles by diaphragms,
fixed substantially as described.
4th. The means of strengthening telegraph poles in the direction of
the strain by making them of oval section with the lower diameter in 2
the line of strain, substantially as described.
In witness whereof, I, the said John Muirhead, junior, have here-
unto set my hand and seal, this Fifteenth day of December, in
the year of our Lord One thousand eight hundred and seventy-
four.
2