Improvements in Equatorial Reflecting Telescopes.
Year: 1894

page_text: Date of Application, 3rd Nov., 1894-Accepted, 5th Jan., 1395
COMPLETE SPECIFICATION.
Improvements in Equatorial Reflecting Telescopes.
I, GEORGE CALVER of Widford, Chelmsford, in the County of Essex,
Astronomical Instrument Maker, do hereby declare the nature of this invention
and in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement:-
This invention consists of various improvements in the construction of astro-
nomical telescopes of the equatorial reflecting type and will be best understood by
reference to the accompanying drawings in which
Fig. 1 is a perspective view of a complete telescope constructed according to this
invention.
Fig. 2 is a vertical section of the equatorial head, upper portion of the pedestal
and other parts hereinafter described.
Fig. 3 is an elevation of portion of the instrument showing the means for
adjustment to latitude, this latter device being also shown in Fig 2.
Fig. 4 is a section of the adjusting nut and screw shown in Figs. 2 and 3.
Fig. 5 is a section of the clamping device for locking the rotatable eye-end of
the telescope tube to the non-rotatable portion; this eye-end for convenience is
hereinafter referred to as the "revolving head."
Fig. 6 is a side elevation and Fig. 7 a front elevation of the device for clamping
and finely adjusting the shaft ordinarily known, and hereinafter referred to, as the
"declination axis.'
Fig. 8 is an elevation of the device for finely adjusting the telescope in right
ascension.
Fig. 9 is a front end elevation and Fig. 10 a side elevation showing the means
for securing the plane mirror in position, the whole device being here shown canted
over as though the eye piece were at an angle of about 30 degrees to the plane in
which is located the declination axis.
Like letters indicate like parts throughout the drawings.
A is the telescope tube which, in general may be of ordinary construction,
though in order to secure the best mechanical and optical results I prefer to machine
the various mounts and parts of said tube before fitting them together; hitherto it
has been customary to fit these mounts and parts together in the rough. At the
lower end of the tube A, by means of the mount BI fit the speculum or concave
mirror not shown in the drawings and in the tube A just above the mount B
is provided a door A' whereby access may be had to the interior of the tube for
cleaning the concave mirror or for other purposes.
The tube A is rigidly secured to the declination axis C by the bridles C₁ and a
head C³ which latter is provided with a socket C³ for receiving the end of said axis.
At the upper end of the tube A, I mount the revolving head D which carries the
"finder" E, eye-piece F and plane or secondary mirror G.
The "finder" E and eye-piece F may be of any ordinary construction.
The revolving head D may be mounted on the tube A in any suitable way, for
example, in the manner shown in Fig. 5 which I have found gives satisfactory
results. In the arrangement here shown A' is a sleeve or socket turned at one
end to receive the upper end of the tube A which is rigidly secured therein, and at
the other end to receive the lower end of the revolving head D which is free to be
rotated thereon. In addition to this I provide means for locking or clamping the
head D in any position to which it may be adjusted on the tube A. A convenient

page_text: .
arrangement for this purpose is to provide externally on the sleeve A* a flange A*
and another D¹ on the revolving head D, and an annular T-shaped groove D' in the
flange D¹ for receiving the heads of two square- or T-headed-bolts D³ which pass
through holes in the flange A', below. which latter they are provided with nuts D*
each having a lever-arm or handle D' to facilitate its operation. When the nuts D*
are loosened upon the bolts D³ the revolving bead D may be turned to any
desired position the T shaped groove D' at such operation sliding over the heads
of the bolts D³; when it is desired to clamp the revolving head D in its adjusted
position the nuts D* are tightened on the bolts D', which draws the two flanges D' A'
together and prevents D being rotated until the nuts are again released. As it is
possible that the nuts D under the weight of the handles D³ might, when these are
at the underside of D, turn upon the bolts Ds and thereby when not required release
the revolving head D, I prefer to provide springs or detents De Figure 1 secured
to the flange A and each adapted to retain one of the handles D' in position
until the latter is positively released by the operator. If desired the before
described clamping device may be reversed that is to say the bolts D³ may have
their heads in a groove in the flange A and their nuts D' above the flange D1 and
instead of two bolts D³ and nuts D* any other desired number may be employed;
or any other desired form of clamping device may be substituted for that shown.
The plane or secondary mirror G as regards itself and the mount G' in which
it is fitted may be of any ordinary construction but as regards the manner of
supporting it in the telescope tube A my invention embraces the following
improvements, viz. :
First, in connection with the plate G' ordinarily known and hereinafter referred
to as the "triangle"; this triangle as usual is supported centrally within the
tube A by means of the three thin-arms or "suspenders" G³ to whose outer ends
are secured the blocks G' conveniently of square section. These blocks G*
pass through square holes in the wall of the tube A so as to prevent the
"suspenders" G from being twisted when the nuts Go are turned on the screws G*
projecting from the outer ends of said blocks G*.
Hitherto no special means besides the nuts G³ have been provided for securing
the outer ends of the "suspenders" G³ to the tube A and, as a result, if, as
sometimes happens the nuts are accidentally loosened the mirror G is thrown out
of adjustment. To prevent this, I lengthen the blocks G so that they may project
to a greater extent than heretofore outwards beyond the wall of the tube A and
on each of these extensions I fit a collar G' (which may form an integral part of A)
provided with a pinching screw G" which latter as shown in Figure 9 may engage
with a recess in the block G, (or the screw G³ may be merely screwed tightly
against the block). The screw G is tightened after the tightening of nut G,
to hold the block G in the position to which it is drawn by said nut.
By this last
described device, should the nut G' work loose, the block Ġ will still be prevented
from moving by the collar G' and screw G and the suspender G³ consequently
maintained taut. Although I have described the blocks G as of square shape in
section it is obvious 1 may use blocks of any other desired section for example
cylindrical blocks each having a key or "feather" engaging with a recess in the
wall of tube A, or having a groove for engaging with a key or projection on said
wall will serve equally well.
A second improvement in connection with the mirror G relates to the means for
securing it to the triangle G. This consists in providing the disc G' to which
the mirror-mount G' is pivotted, as by hinges Go in the usual manner, with six
lugs G two for each arm of the triangle G and providing each of these lugs with
a set screw G" screwing through it. On each screw GI provide a lock-nut G".
G is the usual bolt secured to or projecting from the centre of the disc G' and
passing through a hole formed in the centre of the triangle G wherein it is secured
by means of the nut G". "G" is the usual milled-headed screw for enabling the
mirror-mount G' and mirror G to be adjusted on the hinges G. After the
mirror G by turning it in or on the axis of the tube A, has been adjusted to

page_text: the position it is to occupy in relation to the eye piece F (which may be facilitated
if desired by using one or more of the screws G₁ as the means for turning the
disc G' on its axis) and after the nut G" has been tightened against the triangle G
all the screws G" are tightened upon the arms of the triangle G and the
nuts G¹s are screwed tightly against the lugs G so as to lock the screws G in
these positions and thereby prevent the mirror from being accidentally moved out
of adjustment.
A very important advantage secured by the use of the before-described means of
fitting the mirror G to the triangle over existing arrangements, is that after the
mirror has been once adjusted it may at any time be detached from the triangle G'
and subsequently replaced in the exact same position of adjustment without neces-
sitating further or readjustment such as has hitherto been indispensable in reflecting
telescopes of other construction. To secure this result all that is necessary when
detaching the mirror from the triangle G is to release one lock-nut G" and the
corresponding screw G" of each of the three sets or pairs, say for example, those
marked in Figure 9 and leave the others (9¹) undisturbed, and when replacing
the mirror on the triangle G³ to screw up only those screws and nuts (g) which had
reviously been released. This is a great convenience as it enables the maker
after adjusting the instrument to remove the mirror from the triangle and transport
it in, this condition to the user who may without trouble fit it up in the same
adjustment as when fitted up by the maker.
The foregoing description appertains solely to my improvements in or relating to
the telescope. tube the next. following portion of the description appertains to the
method of inounting and operating it.
H is the pedestal which is provided with the usual base plate H', levelling
screws H and bracket or shelf H³ the latter for supporting the clockwork
motor I, hereinafter referred to as the clock, which moves the telescope in right
ascension.
At its upper part of the pedestal H is provided with two trunnion-bearings *H*
for receiving the trunnions J' which are conveniently formed in part with and project
outwards from the sides of the adjustable frame J. This latter may be adjusted to
any desired angle in relation to the pedestal H and retained in any such position
of adjustment by means of the device shown in Figs. 2, 3 and 4 comprising a
screw J pivotted, between lugs J' to the lower end of the frame J. On this screw
is fitted a nut J' mounted in the bar J pivotted in lugs H secured to or formed in
part with the pedestal H. The nut J' can be rotated in the bar J, but not moved
in the direction of its axis therein, so that any rotation of J', through the screw J³,
will move the frame. J on the trunnions Ji in one direction or the other; this
adjustability of the frame J and consequently of the equatorial head carried
thereby, and not hitherto provided for in reflecting telescopes, enables the same
telescope to be adjusted for, and used in any place, whatever its latitude may be.
If desired, as an extra precaution against deviation, I may provide bolts or
equivalent devices (not shown in the drawings) for clamping the frame J to the
pedestal H or trunnion bearings H' in any position to which it may be adjusted
although such a provision is not actually necessary because the before described
adjusting screw J' and nut J' will be sufficient for the purpose; an extra nut or
other device may however be employed for preventing the nut J* from being
indiscriminately rotated on the screw J.
'
The screw J may be of any desired length according to the range of latitude
adjustment to be given to the telescope.
To one of the trunnions J' I secure an arm K having at one end an index or
pointer Kadapted to work over a segmental scale K2 secured to the corresponding
trunnion bearing Hand at the other end, a vernier K3 adapted to work over the
segmental scale K also fixed to the same trunnion block.
The index K¹ and scale K³ provide only for rough or approximate latitude-
adjustment of the telescope and may be altogether dispensed with in favour of
the vernier K³ and scale K which latter having a larger radius than the scale K³

page_text: may, for a given angle of adjustment, be more finely divided and the readings be
more easily discerned.
Though not shown so in the drawings, the scale K' may be sufficiently long to
accommodate the vernier K throughout the 90 degrees of latitude-adjustment of
which the telescope is susceptible. The scales KK or their markings on the
trunnion bearing, H, and the arm K on the trunnion J' are so arranged that after
the pedestal H. has been adjusted in azimuth, as it must be when the instrument is
being erected the index K¹ and vernier K³ will correspond with the 90 degree
marks of the respective_scales K K when the equatorial head and declination
axis C are horizontal. This would be the position of adjustment if the instrument
were to be erected for observation at the north pole; when the telescope is adjusted
for use at the equator the equatorial head and the declination axis C are vertical
and the index K¹ and vernier K³ will point to the 0 or zero of their respective
scales K K corresponding with the degree of latitude of the place at which the
telescope is erected. Consequently all that is necessary in erecting the telescope
at any place is, after adjusting the pedestal H in azimuth, to turn the nut J* so as
to swing the frame J on its trunnions until the index K' or vernier K³ points to a
number of the scale K2 or K* corresponding with the known latitude of the place,
after which the instrument will be ready for observations. Hitherto this has not
been provided for because the equatorial heads of reflecting telescopes have been
made in one with, or rigidly secured to their pedestals or at most only a small
amount of rough adjustment has been allowed, and each such arrangement had to
be specially designed to suit the latitude of the place at which it was to be used;
whenever therefore it was found necessary to adjust such an instrument to latitude
this was only effected either by throwing the pedestal out of its proper vertical
position which also disturbed the level of the clock or by, in some way, as by
wedges or equivalent disturbing the position of the equatorial head in relation to
the pedestal, the true adjustment under either of these operations not being arrived
at without involving the making of a great number of observations and consequently
an expenditure of a considerable amount of time.
;
At its upper part, the frame J terminates in a ring or table J having a hollow boss
or sleeve projecting upwards from it, this sleeve being cylindrical at its exterior
and at its interior preferably slightly tapered as shown. The ring and sleeve JJ'
form an annular bearing on which a ring L, which with its boss L' is hereinafter
termed the "clock circle," is free to rotate. This clock cirdle is shaped to
correspond with the bearing surfaces of J J7 and its central boss L¹ has an
external taper surface to fit within the boss or sleeve J*. The clock circle
provides bearings.for the ring M hereinafter referred to as the "hour circle" for
the upper end of the spindle N hereinafter referred to as the "polar axis" and
for the disc N¹ and ring O.
The disc N' and polar axis N are formed in one with or rigidly connected to
each other.
'.
The outer or exposed surface of the clock-circle L is formed with rack-teeth L'
with which engages a worm, I Fig. 2 rotated in the usual way by the clock 1.
The shaft I through which the motion is transmitted from the clock to the
clock-circle L is telescopic so that it may be lengthened or shortened according
to the position of the worm I which is adjustable along with the equatorial
head.
The hour circle M is provided with a toothed rack M¹ with which engages a
pinion M³ fast on a spindle M. This spindle is provided with a milled head M
and is mounted in bearings M' secured to the outer edge of the ring or table J';
ly rotating the pinion M' the bour circle M may be turned to any desired
Josition. The hour circle at its outer surface or edge is also provided with scale
arkings which, in conjunction with a vernier N secured through N¹ to the polar
xis N and another vernier J8 secured to the ring Jo serve to give time readings
4r provide for the making of adjustments for time or right ascension.
The ring is provided with one or more screws O by means of which it may,

page_text: when desired, be temporarily secured to the clock-circle L. The outer ends of
the screws O¹ do not project beyond the outer surface of the ring so that they
form no obstacle to the movement of the vernier N' which is not in any way
connected with the ring O.
By the term "equatorial head" herein employed I mean the device in which
the declination axis is mounted and which is rotated by the clock.
may
To the ring O as clearly shown in Fig. 8 is also secured a bracket P pivotally
supporting a nut P¹ through which passes the screw threaded end of a spindle P*
supported in a bearing P³ pivotally mounted in a bracket P secured to the edge
of the disc N¹. On the spindle P' are secured a milled head P5 by which it
be rotated directly by hand, and a toothed bevel wheel P in gear with a wheel P'
mounted on a conveniently square-ended shaft P8 supported in a bearing P* formed
preferably in one with the before mentioned bearing P'. The last mentioned
shaft is provided to enable a flexible or universally jointed shaft (not shown in the
drawings) being applied to it so as to admit of the threaded spindle P' being
rotated by the observer when he is looking through the eye-piece F or otherwise
out of convenient reach of the milled head P. Whenever the threaded spindle P*
is rotated the disc N' is moved independently of the ring O this movement being
in right ascension.
To roughly adjust the instrument to any point in right ascension the screws 01
are released and the telescope may be freely swung round into any desired
position. To accurately adjust the instrument to any point in right ascension
the screws are tightened so as to secure the ring O to the clock-circle L and
the threaded spindle P2 is rotated so as to turn the disc N¹ independently of the
clock-circle which is itself prevented from turning by the rack L³ being in gear
with the worm I'.
The before described arrangement of the parts L L M N N₁ and O is such
that even when the screws 0₁are released sufficient friction exists between said
parts to enable the clock-circle during its rotation to carry the parts M N N¹
and Oround with it, while, at the sanie time the observer is free to make any
extensive or rapid adjustments in right ascension by swinging the telescope around
the polar axis, the clock carrying the telescope onward whenever the latter is
released by the observer.
In reflecting telescopes as hitherto constructed the last described feature does
not exist and when it is required to manually adjust these telescopes in right
ascension they have to be first unclamped from the clock-circle and after such
adjustment, is made, be again clamped to the clock-circle as without this
re-clamping they are not in operative connection with the clock and consequently
remain stationary.
At its lower end, the polar axis N is supported on the foot-step-screw or bolt J'
which is adjustable in the frame J and may be secured in any desired position
therein by the lock-nut J¹º.
:
The disc N is provided with two diametrically opposite bearings N³ for
supporting the declination axis C and these bearings, may if desired, be connected
together by a bridge N¹.
On the declination axis C, I provide the spring clamp Q Fig. 6 to steady or
more or less tighten without rigidly fixing it and preferably located between the
bearings N and whose two arms Q' Q are connected together by a screw Q³
provided with a handle Q by means of which screw, handle and arms the clamp Q
may be tightened upon the declination axis C. Of the two arins QQ the shorter
one (Q) terminates just outside the screw Q3 and the longer one (Q) is forked
at its end and provided with rounded heads Q which engage with recesses Q
formed one at each side of a nut Q capable of being raised and lowered by the
turning the screw-threaded shaft Q which engages with and passes through it as
shown clearly in Figs. 6 and 7. The shaft Q on which is secured a toothed
wheel Q is supported perpendicularly to the disc N¹ in a frame Q rigidly

page_text: mounted on said disc, the sides of the frame Q serving to guide the nut Q in its
up and down movements. Q10 is a spur pinion engaging with the wheel Q and
secured upon the shaft Q" which is provided with bearings in the frame Q. On
this shaft Q is secured a hand wheel Q" by means of. which it may be directly
rotated by hand and at its upper end said shaft is formed square to admit of the
connection of a flexible or universally-jointed rod (not shown in the drawings) to
enable the nut Q to be raised and lowered by the operator when he may be at the
eye-piece F or otherwise out of reach of the hand wheel Q
Qis a segmental clamping plate, which I may provide in addition to the last
described device, located in a recess formed in the inner side of the clamping
ring Qand which by the screw Q4 may be forced more or less tightly against the
declination axis C; when this plate Q and screw Q" are employed the before
described bridge N Fig. 2 may have a slot or opening to admit of the screw Q
passing through it and being readily accessible, or the bridge N₁ may be altogether
dispensed with.
The screw Q and plate Q1 may be so adjusted as to prevent at any time the
too-free rotation of the declination axis C to ensure that when the telescope is
moved by hand in declination it will not gain sufficient impetus to carry it beyond
the desired point.
When it is desired to only approximately adjust the telescope in declination the
screw Qis released and the telescope together with the declination axis may be
swung round, C acting as the pivot to any desired position. When it is desired to
accurately adjust the telescope in declination the screw Q³is tightened and the
shaft Qis rotated so as to raise or lower the nut Q and thereby, through the
arm Qturn the declination axis C to any fractional extent, the precise position
of adjustment being ascertained by means of the usual declination scale R secured
to C and the vernier R' secured conveniently to the adjacent bearing N³.
C is the usual weight mounted on the declination. axis for counterbalancing the
weight of the telescope A and its direct attachments.
A feature of the before-described instrument which is designed to facilitate its
general manipulation, is the location of the right ascension and declination adjusting
and clamping devices at the front and centre of the instrument where they are most
convenient for operation, they being in readily accessible positions whether the
telescope be at the east or west of the pedestal.
Various details of the before described instrument may be modified without
departure from the spirit of the invention, for example instead of the device
represented in Figs. 6 and 7 being located in the position shown in Fig. 1 I may
locate it elsewhere a convenient arrangement, for instance, being one in which
screw adjusting mechanism Q Q' etc. is mounted on the bridge N
By the term "; adjustable herein used in connection with the adjustment in
latitude of the telescope or equatorial head in relation to the pedestal or stand,
I mean an adjustment such as is provided for by pivotting one part on another and
not an adjustment necessitating the disturbance of any of the permanent fittings such
tor example as when the before mentioned wedges are employed.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. A reflecting telescope instrument which may be erected in proper operative
position at any part of the world where the latitude is known without necessitating
the making of preliminary astronomical observations.
2. A reflecting telescope instrument in which the telescope is adjustable in
latitude independently of the pedestal or stand.
3. A reflecting telescope instrument in which the telescope is capable of being
adjusted in latitude without the disturbance of any of its rigid connections with
the pedestal or stand supporting it.

page_text: 4. In a reflecting telescope instrument the combination with the telescope and
pedestal or stand of a frame such as J pivotally connecting them together
substantially as described and illustrated in the accompanying drawings.
5. In a reflecting telescope instrument the combination with the telescope
pedestal or stand and a frame such as J pivotally connecting them and supporting
the polar axis of a scrow and nut attachment such as J'JJ' for adjusting the
telescope in latitude substantially as described and illustrated in the accompanying
drawings.
6. In a reflecting telescope instrument the combination with a telescope and a
pedestal by which it is supported and in relation to which it is adjustable in
latitude of an index or vernier and scale for indicating the position to which the
telescope is to be adjusted for any given latitude substantially as described.
7. An equatorial head for a reflecting telescope instrument so arranged that the
telescope normally moved in right ascension by a motor may also be similarly
moved by hand the motor automatically resuming its control simultaneously with
the cessation of the application of the manual power.
8. In the equatorial head of a reflecting telescope instrument the arrangement
of a clock-circle such as L and disc such as N in such manner that without
Decessitating any clamping or un-clamping operation the telescope may at will be
moved in right ascension either by hand or by the clockwork motor the telescope
being controlled by the clock when the application of the manual power ceases
substantially as described and illustrated in the accompanying drawings.
9. In an equatorial head for a reflecting telescope instrument the combination
of a table such as J J' clock-circle such as L L L and hour circle clamping ring
and disc respectively such as M O and N¹ all operating substantially as and for
the purposes described and illustrated in the accompanying drawings.
10. In the equatorial head of a reflecting telescope instrument the employment
in combination with a clock circle clamping ring and disc respectively such
as L O and N¹ of a device for rotating the disc independently of the clamping
ring constructed and operating substantially as described and illustrated in
Figs. 1 and 8 of the accompanying drawings.
11. In a reflecting telescope instrument mounting the polar axis in a pivotally-
supported frame such as J substantially as described and illustrated in the
accompanying drawings.
12. In a reflecting telescope instrument the combination with the declination
axis of a clamping and adjusting device constructed and operating substantially as
described and illustrated in Figures 6 and 7 of the accompanying drawings.
13. In a device for clamping and adjusting the declination axis of a reflecting
telescope instrument the combination with a clamping ring having arms such
as QQ capable of being moved closer together or tarther apart by a screw Qof
a nut such Q and screw or screw threaded shaft Q for adjusting the clamping
ring and through it the declination axis substantially as described and illustrated
in the accompanying drawings.
14. In a reflecting telescope providing the plane-or secondary-mirror with
means which after said mirror has been adjusted on the triangle to the position
it should occupy in relation to the eye piece may also be adjusted and locked
in their adjusted position so that the mirror after being detached from the
triangle may be replaced without readjustment in exactly the same position which
it occupied before such detachment.
15. In a reflecting telescope the combination with the plane or secondary
-mirror of set screws G" and lock nuts G¹³ substantially as and for the purpose
described and illustrated in Figures 9 and 10 of the accompanying drawings.
15. In a reflecting telescope the combination with a suspender and block such
as G³ G of a collar G' and pinching screw G substantially as and for the purpose
described and illustrated in Figure 9 of the accompanying drawings.
16. In a reflecting telescope the combination with the relatively fixed and
movable parts of the telescope tube of a clamping device comprising two flanges

page_text: such as A³ D' one perforated and the other grooved and one or more bolts D)* and
nuts D substantially as and for the purpose described and illustrated in Figure 5
of the accompanying drawings.
17. The combination and arrangement of parts constituting the complete
reflecting telescope instrument substantially as described and illustrated in the
accompanying drawings.
T
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