IMPROVEMENTS IN TELESCOPES
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by Antoine Julien Hypolite
Delcarte at the Office of the Commissioners of Patents, with his
Petition, on the 15th October 1875.
I, ANTOINE JUlien HypolitE DELCARTE, of St. Gilles, Brussels, in
the Kingdom of Belgium, Merchant, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN TELESCOPES," to be as follows:-
This Invention relates to an improved Galilean and astronomical
telescope, and to certain modifications in the arrangement of the concave
and convex glases of telescopes.
When lenses with convex surfaces are combined with a glass of the
same or of a different kind, but the surfaces of which are concave the
telescope known as the Galilean is obtained, the astronomical tele-
scope being produced by the combination of two convex lenses, the same
effect being producible with the six classical forms of lenses. The
production of an erect image is obtained in land telescopes by the inter-
position between the object glass and the eye glass of two or more
lenses.

page_text: If in a single block of glass a convex surface be cut opposite to a
concave surface the effects of a Galilean telescope arc obtained in a very
portable form. If instead of leaving the block entire two parallel
surfaces be removed so as to have a kind of rectangle, terminating on
the one side in a convex surface and on the other in a concave one, they
are fragments of lenses cut at equal distance from their diameter. But
the distance between the two surfaces receiving and transmitting the
light must be capable of displacement at pleasure, all that is required
for this purpose being to cut the single piece of glass in a parallel plane
as at A, B, of the diagram in the margin. The
flattened form of such glasses permits their being
casily fitted with an outer case in which cach glass
is fixed, so that it may be drawn in and out like an
opera glass.
A
B
The diagrams on the accompanying Sheet of
Drawing give the form of a glass of this kind.
1°. Either of a single piece, as at Fig. 1, of an elongated square
shape, convex in its breadth at one end A, termed the object glass, and
concave at the other or eye end B; C is a plan view of the eye end, and
D a side view of the entire piece. This same piece instead of being of
an elongated square form, as shown, may be of a conical form, as
indicated by the bluo lines Fig. 1.
2°. In two pieces, as at Fig. 2, enclosed in a sliding case as at Fig. 3.
The piece A of Fig. 2 is also convex in its breadth at one of its ends
termed the object glass. This piece is a single glass, but it may be
composed of two or three glasses cemented together to render it
achromatic. The dotted lines B and C, Fig. 2, indicate the junction of
these glasses; D indicates the inner flat part and E the side of the said.
piece A. The piece F is concave on both inner and outer surface, and is
termed the eye pieco; G is a plan of same. This picce may also be
composed of several glasses cemented together to make it also
achromatic.
The picces A of Fig. 3 form a case of metal, cardboard, or other
suitable material, in which are placed and held the pieces A and F of.
Fig. 2.
This case has a slide for drawing the object glass and the
cyc piece nearer to or further from each other, and thus suiting the glass-

page_text: to every sight. Between the two pieces A the object glass and F the
eye piece and within the case is placed a diaphragm.
The metrical size of all these pieces is not indicated on the Drawing,
because they may be made of all sizes and with curves which will
permit placing the real or virtual focusses wherever I may desire,
reserving as aforesaid the right of using the curves A of the Drawing,
1°, bi-convex, 2°, plano-convex, 3°, converging meniscus; B, 1°, bi-
concave, 2°, plano-concave, 3°, diverging meniscus.
The details above given for the construction of a Galilean telescope
render it unnecessary to give here details of the construction of an
astronomical glass with or without crection of the image. The same
arrangements are used, and in each kind of telescope the curves most
suitable for the person using it whether to see very distant objects or
those nearer.