IMPROVEMENTS IN EQUATORIAL TELESCOPES
Year: 1874

page_text: LETTERS PATENT to Edward Lyon Berthon, Clerk in Holy Orders,
of Romsey, in the County of Southampton, for the Invention of
"IMPROVEMENTS IN EQUATORIAL TELESCOPES."
Scaled the 16th June 1874, and dated the 18th April 1874.
PROVISIONAL SPECIFICATION left by the said Edward Lyon Berthon
at the Office of the Commissioners of Patents, with his Petition,
on the 18th April 1874.
I, EDWARD LYON BERTHON, Clerk in Holy Orders, of Romscy, in
the County of Southampton, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN EQUATORIAL TELESCOPES," to be as
follows:-
This Invention relates to improvements in equatorial telescopes, and
consists in,-
Firstly. Constructing telescopes with two counterpoises.
Secondly. The employment of a curved screw and special shaped nut
to work thereon.
And, thirdly. Supporting and poising an equatorial telescope.

page_text: The first essential peculiarity of this instrument consists in its having
not as usual one counterpoise, and that upon the declination axis, but.
two counterpoises below that axis, the tube of the telescope itself being
placed as much above it. There are two modes of applying this new
method of balancing a telescope, so that it shall rest in any position
and move with an equatorial motion, the first being that of a disc or
stage rotating (with or without rollers) upon another disc so tilted as
to be quite parallel to the equator, the second being that of a cylinder
nicely fitting over and rotating upon another cylinder, which is placed
in a position pointing to the pole of the earth.
66
The second novelty consists in the band movement in "right
ascension," which is not effected in the usual way by means of a
tangent screw," but by a nut travelling along a screw rod bent in a
segment of a circle. The nut or female screw is tapped in a peculiar
way, as in the accompanying Drawing, in order to make it work in
a circular direction without shake or "slop" or unequal pressure. The
'driving clock" or automatic mover also works similarly upon a
curved screw. It is attached to a radius bar over the revolving disc
or stage and propels the telescope by being clamped down to the lower
disc.
"
The third peculiarity is confined to the double counterpoise equatorial,
viz., the end of the pivots attached to the lower disc, and about which
the upper one revolves, is the very centre of gravity of the whole mass;
upon this point the entire weight is actually poised, so that friction is
reduced to a minimum.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Edward Lyon Berthon in the Great Scal Patent
Office on the 17th October 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
LYON BERTHON, Clerk in Holy Orders, of Romsey, in the County of 3
Southampton, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighteenth day of April, in the year
of our Lord One thousand cight hundred and seventy-four, in the

page_text: thirty-seventh year of Her reign, did, for Herself, Her heirs and.
successors, give and grant unto me, the said Edward Lyon Berthon, Her
special licence that I, the said Edward Lyon Berthon, my executors,
administrators, and assigns, or such others as I, the said Edward Lyon
Berthon, 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
"IMPROVEMENTS IN EQUATORIAL TELESCOPES," upon the condition (amongst
others) that I, the said Edward Lyon Berthon, my executors or adminis-
trators, 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 Scal Patent Office within
six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW VE that I the said Tidword Lvon Borthen do honohy

page_text: "
The second novelty in this Invention consists in the driving move-
ment in "right ascension," which is not effected by the usual way by
means of a tangent screw," but by a nut travelling along a scrow
rod bent in a segment of a circle. The nut or female screw is tapped
in a peculiar way in order to make it work in a circular direction
without shake or "slop" or unequal pressure. The "driving clock" or
"automatic mover" also works similarly upon a curved screw. It is
attached to a radial bar over the moving disc or stage and propels the
telescope by being clamped down to the lower disc..
Also in both these forms of balancing this telescope there are two
equal counterpoises instead of one as in the German and other equa-
torials, and they are not placed, as they usually arc, on the end of the
declination axis, but on one side of it, while the body of the telescope
is on the other side. Both these forms of telescope can be moved by a
tangent screw or by means of the bent screw, hercin-after described,
and both are applicable for reflectors and refractors.
The first form above refered to is shown in Figure 1. a, a, the body
tube of the telescope rotating in its cradle b. c, c, the upper disc of
iron or other metal upon which is cast a pair of trunnions d, d, whercon
an arched arm e, e, on each side works; see also Figure 2. Attached
to the upper ends of these arched arms is the cradle 6 of the body
tube a, and to their lower ends the counterpoises f, f. A pair of rods
on each side g, g, extending from the arms near the trunnions to the
ends of the cradle complete its support and remove all tendency to
vibration.
It will be observed that the counterpoise being properly adjusted the
centre of gravity of the whole mass is situated at the central pivot h.
This pivot is attached and belongs to the lower disc i, i, and by means
of a little plate h¹, of iron, steel, or other metal, perforated for screws j, j,
which are tapped into the upper disc, nearly the whole weight may be
thrown upon the end of the pivot h.
Over and fixed to the upper disc is a semicircular arch k called the
declination arch, which serves two purposes, the first that of carrying
the declination graduated semicircle (the vernier being attached to the
cradle), the second that of fixing a rod 7, called the declination rod,
which is clamped to it in any part. by means of a thumbscrew m. The
other end of this rod passes through a strong eyen on the cradle and

page_text: having a screw thread on it receives two milled nuts p, p, one above
and the other below the eye for delicate movement in declination.
The right ascension circle consists of a shifting band of metal on the
circumference of the lower disc i, to which last a meridian vernier is.
attached and another vernier is also fixed to the upper disc..
The slow motion in right ascension, if not effected by a tangent
screw in the usual way, is produced as follows:-Revolving about the
central pivot, see Figure 3, is a radius bar q with a clamping screw r
at the free end in order to fix it to any part of the lower disc, and
firmly attached to it is a curved screw &, which passes through the
grooved nut t, shown separately in Figure 3, working in bearings on
the declination arch k, which is perforated for it to pass through. This
nut has a female thread cut with a taper tap from both sides, which
makes it perfectly accommodate itself to the curvature of the bent
screw 8. A cat-gut vor other line passing round the groove in this
nut and through little sheaves w near the centre pivot and on the cradle
enables the observer, by a gentle movement of the lever x and wheel 10,
to move the telescope in right ascension. The bent screws is long.
enough to carry the telescope about two hours in right ascension, after
which a rapid reverse movement will run it back to its starting place.
When this form of telescope is to have automatic motion clockwork
is attached to another radius army and the bent screw has an additional
length with a cogged or toothed nut z working in bearings on the radius
bar and gearing into the driving wheel of the clock. The line of the
clock passes down through the central pivot, which is bored out for the
purpose, and the weight descends inside the pedestal. The speed of
the clockwork, and consequently the movement of the telescope, is
regulated by a fly of peculiar construction, shown clearly in Figures 3.
and 4, called an expanding fly, in as much as it opens out and closes up
its wings A, A, according to the degree of resistance. The wings A, A,
are attached to spindles B, B, on which are also spur wheels C, C, taking
into a wheel D on the central axis of the fly, the wheel D being under
the control of a coiled spring E and regulator F, the whole being
carried on a thin disc of metal G, which is itself secured, and revolves
with the spindle H of the train of clockwork.
In the second form of this instrument, Figures 5 and 6, there are no

page_text: declination movement. A tube h forming the polar axis is ground to
fit another tube I, which rotates upon it, and to this is soldered another
short piece J of the usual size, at right angles. Within this last piece
another piece of tube K well ground to fit, rotates as the declination axis,
and attached to the ends of it are two semicircular side plates L, L.
The body tubo a of the telescope is fastened to these latter plates, as
shown in Figure 6, the semicircular parts of which with additional
weights, if necessary, act as counterpoises. The telescope shown in
Figure 6 may be readily rendered portable by placing the inner end of
the body tube a in a vertical position, and causing its end to take into
a recess in the foot of the stand W, as shown in dotted lines, the outer
end of the body tube being unscrewed and stood on end by its side.
Another modification of this form, so far as the axes of rotation are
concerned, is shown in Figures 7 and 8, which is better adapted to large
instruments. The internal or central stem consists of a cylindrical
portion M and a pivot N, Figure 5, and the cup or revolving part P is
cast in one piece with short trunnions Q, Q, Figure 8, upon which the
side plates L, L, carrying the telescope revolve. In this form of
telescope the polar axis may be either cylindrical, conical, or any other
figure of revolution, so that the revolving part outside fits it well. This
form can also be moved in right ascension either by means of a tangent
and screw or by the curved screw 8, above described, but when the latter
is used in this form it is carried in a frame R, Figure 9, attached to a
brass band S on the circumference of the moving part of the polar axis
and fastened there or released at pleasure by a milled headed screw T.
The declination semicircle is on one of the side plates Land the decli-
nation tangent screw on the other. The right ascension circle is a moving
band on the rotating portion of the polar axis.
It will be observed that the above descriptions apply primarily to
reflecting telescopes of the Newtonian type but in other reflectors, as
well as in all refractors, the cradle is dispensed with and the body tube.
itself is treated as the cradle.
And having now described the nature of my said Invention, and in
what manner the same is to be performed, I declare that I claim,—
Firstly. The double counterpoise arrangement for equatorial telescopes, a
as shown in Figures 1, 5, and 6 of the accompanying Drawings.