Improvements in Equatorial Telescopes.
Year: 1898

page_text: Improvements in Equatorial Telescopes.
I, EDWARD LYON BERTHON, of Capernham, Romsey, Hants, Master of Arts, do
bereby declare the nature of this invention to be as follows.-
1
This invention has for object, the construction of equatorial telescopes of a less
weighty and bulky character, whereby they can be made portable and less costly and
by which equally good or better results can be obtained.
For the purpose of my invention, I dispense with the usual verniers and I substitute
therefor a screw and nut which turns or can be turned once for every degree of
declination, a disc on the uut having 60 divisions on its periphery, so that each
mark will represent one minute of are and this can again be subdivided into
seconds.
I also dispense with the usual tangent screws and substitute a curved screw in lieu
thereof.
"
The "main
is divided in the middle in order that in packing in a case prepared
to receive the apparatus it can occupy a small area, which case contains the three
metal legs on which with the case the instrument can be erected for work.
By this invention, an equatorial telescope 18 for the first time made portable,
the heavy counterpoise being unnecessary and without in any way interfering with the
facility of working, or with its accuracy.
ALL
1000
I, EDWARD LYON BERTHON, of Capernham, Romsey, Hants, Master of Arts, 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 has for object, the construction of equatorial telescopes of a less
weighty and bulky character, whereby they can be made portable and less costly and
by which equally good or better results can be obtained.
For the purpose of my invention, 1 dispense with the usual verniers and I substitute
therefor a sorew and nut which tuins or can be turned once for every degree of
LD
017

page_text: declination, a disc on the nut having 60 divisions on its periphery, so that each mark
will represent one minute of are and this can again be subdivided into seconds.
I also dispense with the usual tangent screws and substitute a curved screw in lieu
thereof.
The "main" tube 18 divided in the middle in order that in packing in a case
prepared to receive the apparatus, it can occupy a small space, which case contains
the three metal legs on which with the case the instrument can be erected for
work.
By this invention, an equatorial telescope 18 for the first time made portable, the
heavy counterpoise being unnecessary and without in any way interfering with the
facility of working, or with its accuracy
My invention will be fully understood by reference to the annexed drawings
Figure 1 side elevation.
Figure 2 similar view partly in section.
Figure 3 plan, and Figure 4 plan of detail.
Figure 5 section of detail
My invention consists in improvements in equatorial telescopes of moderate size by
which such instruments are made portable and universal, and though constructed
without verniers, they read to half a minute in declination, and one second in right
ascension. They are equally adapted to any latitude from, the Equator to the
Poles.
As for portability, a telescope with 4 inches aperture of object glass, and 50 inch
focus may be contained in a three-sided case of oak, 2 feet 2 inches high and 1 foot
wide weighing altogether 65 lbs. This case can contain beside the telescope, three
affixable legs of iron upon which the said case being erected forms the complete stand
or pedestal of the proper height.
The circles for reading declination and night ascension are divided, the former into
single degrees, the latter into ten minutes, and by a new arrangement the fine reading
in declination 18 done by means of a screw X on which a circular nut Y divided into
60 marks revolves once for every degree, so that each division indicates by an index
one minute of arc.
The movement in right ascension 18 effected (without any tangent screw) by means
of a nut D that revolves in suitable bearings and moves a screw E bent into a segment
of a circle. The pitch of this screw and its radius of curvature are such that at each
turn the telescope is moved two minutes in R A. A disc on the nut (about three
inches in diameter) 18 so divided that in each half there are 60 divisions, each
division being a second of time.
The main tube is made in two parts G, G4, united by a bayonet or screw joint Gu
(as shown) for reducing its length for packing.
To erect the instrument for use, the oak case is erected on the three iron legs, and
the two parts of the main tube united It 18 then placed approximately in the meri-
dian by the compass and the spirit levels, two in number, vis.: one on the main
tube, the other on the zinc foot.
The latitude of the place being known, the axis 18 approximately elevated or
lowered to the co-latitude, and final adjustment made by the screws on the foot.
It is found in practice that the diameters of the Lunar craters and their distance
from each other can be measured by means of the declination screw.
For the purposes of my invention and as represented on the Drawings; a short
rod A with a Hooke's joint B is capable of tine hand movement which rod turns by
the cord C the nut and disc D on the curved sorew E, or if desired this movement
may be effected by clockwork contained inside the conical stem F', a little spring (not
shown) preferably falling into a notch to mark audibly each minute as the telescope G
is moved in accordance with the rotation of the earth,
The nut D which moves on the curved screw E 18 tapped in such a manner, see
Figure 5, that all the turns of the thread touch equally on all the turns of the inner
side of the screw, and the middle one touching on the middle turn keeps them in
continual contaot. One advantage of this over the usual tangent screw 18 that the

page_text: known imperfection of the latter in which only one turn is in perfect contact 18
avoided and by the contact of many turns the mean of all is kept up (see the section
of this nut).
The proper amount of tension on the driving band C 18 maintained at all
degrees of elevation of the main axis by means of the nut H moving on the bent
Bcrew I.
The various parts shown on the drawings but which are not denoted by reference
letters are of the ordinary construction and will be understood without more detailed
description.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what I
claim is:-
1. The construction of portable equatorial telescopes without verniers and tangent
screws and substituting therefor a curved sorew E on which a threaded nut of
the shape shown at Figure 5 can be operated, said nut carrying a disc D suitably
marked as degrees, as described and substantially in the manner or position indicated
on the annexed drawings.
2. A portable equatorial and universal telescope constructed, mounted, and
operated by the means or appliances above set forth and arranged as
represented.
The 9th day of March 1899.
H. GARDNER,
Patent Agent, 166, Fleet Street, London,
Agent for the said :-
Edward Lyon Berthon.