CERTAIN IMPROVEMENTS IN THE CONSTRUCTION OF PAPER AND VELLUK TUBES FOR TELESCOPES, AND IN THE OPTICAL PARTS OF TELESCOPES
Year: 1815

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, DUDLEY
ADAMS, of Fleet Street, in the City of London, Optician and Mathematical
Instrument Maker, send greeting.
WHEREAS His most Excellent Majesty King the Third, by His Royal
Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Seventh day of March, in the fifty-fifth year of His reign,
did give and grant unto me, the said Dudley Adams, my exors, adñiors, and
assigns, His special licence, sole priviledge and authority, during the term of
fourteen years, to make, use, exercise, and vend, within that part of the United
Kingdom of Great Britain and Ireland called England, the Dominion of
Wales, and the Town of Berwick-upon-Tweed, and also in His said Majesty's
Colonies and Plantations abroad, my Invention of "CERTAIN IMPROVEMENTS
IN THE CONSTRUCTION OF PAPER AND VELLUK TUBES FOR TELESCOPES, AND IN THE
OPTICAL PARTS OF TELESCOPES," and to have and enjoy the sole profit, benefit,
and advantage thereof during the said term; in which said Letters Patent
there is contained a proviso obliging me, the said Dudley Adams, by an
instrument in writing under my hand and seal, particularly to describe and
ascertain the nature of my said Invention, and in what manner the same is
to be performed, and cause the same to be inrolled in His Majesty's High
Court of Chancery within two calendar months next and immediately after
the date of the said recited Letters Patent, as in and by the same, relation
being thereunto had, may more fully and at large appear.

page_text: NOW KNOW YE, that I, the said Dudley Adams, in pursuance of and
compliance with such proviso in the said recited Letters Patent contained,
do, by this Instrument under my hand and seal, particularly describe and
ascertain the nature of my said Invention, and in what manner the same is
to be performed, by the explanations, descriptions, and Drawings herein-after
contained and referred to (that is to say) :-
-
The first part of my Invention is an improved method of making tubes,
composed of paper and vellum, of a form perfectly cylindrical, and of sufficient
strength to receive and hold metal screws, and other parts necessary to the
construction of telescopes of various kinds and sizes in common use, and of
mounting and putting the tubes together in such a manner as that the varnish
and ornamental figures or devices of painting or gilding on their outsides may
not be injured by drawing out or closing the tubes.
The method of making the tubes is as follows:-
I compose the tubes of paper and vellum in the following manner:-
1st, a coat of post or writing paper, which I call the water coat. 2ndly, another
coat of post or writing paper. 3dly, a coat of blue, brown, or bag cap.
4thly, another coat of post; and lastly, the vellum, thus forming a substance
consisting of four coats of paper, pasted one on the other, and so on according
to the diameters of the tubes, increasing in number of coats as the sizes may
be augmented, applying last of all the coat of vellum. The above-mentioned
number of four coats of paper is found to succeed for tubes to the extent of
two inches in diameter, beyond which a coat or coats of post or writing paper
may be added as shall be found requisite. The substance so composed is
formed into tubes by being pasted on moulds or treblets made of brass or
compound metal, which are adapted to the implement called a draw bench,
hitherto used for drawing brass or metal only, and drawing the same through
brass holes made for that purpose. The tubes are tempered to a certain
hardness by drawing them through one, two, or more holes, which is absolutely
necessary to make the tubes cylindrical, round, and of a true form; it also
renders them, by the correctness of their shape, fit to receive brass or metal
rims, rings, and screws.
The side of the first coat of paper, which I call the water coat, (viz',) that
which is intended to form the inside surfaces of the tubes, is stained black
previous to its being put on the treblet; any black stain may be used, but
I prefer the following preparation, viz, Indian ink with common writing ink,
in the proportion of a quarter of an ounce of the former to a gill of the latter,
to which may be added about half a quarter of an ounce of gum, well dissolved
in about half a gill of water. This preparation is laid on the said first coat of

page_text: paper with a brush, and the said first coat of paper, while wet with it, is placed
on the treblet, which is previously greased with suet or other grease. The
first coat of paper, or water coat, may, however, be moistened with water only
previous to its being placed on the treblet, and in that case the inside surface
of the tubo may be afterwards stained black with the said preparation by
means of a brush dipped in it being drawn through the tube.
The next or second coat of post or writing paper is to be well moistened
with paste on both sides and then laid on the water coat; this should be
accomplished while the latter is yet moist. The brown or blue paper is laid
on the second coat after the same manner, and there the work ceases till the
coats so pasted together are dry and hard enough to admit of its surface being
levelled, which is effected by filing. This process is necessary in order to
correct the inequalities and remove the gritty substances which are generally
to be found in paper, but especially in the brown or blue sorts. When the
last-mentioned surface is made smooth the next coat of post paper should be
pasted therecn, and last of all the vellum. Care should be taken to incor-
porate the paste well with the paper, and in the stiffer sorts of paper it would
be proper to moisten them in water, first of all squcesing the same out by
presure previous to the application of the paste. This precaution should be
observed with the outer or vellum coat also. The paste is made in the usual
manner, with the exception that a small portion of powdered rosin (about a
quarter of an ounce to a pint, should be put into it) in order to stiffen it.
The treblets are for the most part made hollow; in the larger sizes they are
cored thro' in the casting; in the smaller ditto they are drilled or bored,
and in the smallest of all they are left solid. The reason for their being made
hollow is in one respect to reduce the quantity of brass or metal, thereby to
save expence; in another point of view to enable the workman to place
therein an iron heater made red hot, by the aid of which artificial heat the
moisture contained in the different coats is dried with tolerable quickness; the
same is thereby sooner prepared for the draw bench, and the whole of the
subsequent mechanical process expedited.
A, Fig. 1, in the Schedule or Drawing hereunto annexed, exhibits a view of
one end of the treblet, made hollow to receive the heater.
Fig. 2 the other or that end called the tang, which is fitted into the end B
of the treblet, Fig. 1, either by a screw or with plain surfaces, and then pinned,
a mode adopted in preference to soldering, which would soften the metal.
At C, Fig. 2, is represented a groove made to receive a bandage of string. This
is applied to each coat while in a moist state, in order that the same should
acquire the form of the groove, which being effected, it is then removed till

page_text: the last coat is put on, when it is bound tight and suffered to remain till the
process of drawing is performed. It will appear obvious that this plan is
adopted in order to provide against and to resist the great force employed in
drawing the tubes through the required holes. D, in the same Figure, repre-
sents the slit to receive the key that passes into the treblett through the tongs
or chops at the end of the chain appertaining to the draw bench.
Figure 3 exhibits the form of the heater. Moistened soap or grease
should be applied to the surfaces of. the holes, and the same to the surfaces
of the vellum; good starch in a fluid state answers the purposes equally.
well, and in some instances is to be preferred. The method of mounting
and putting the tubes together is as follows:-The different sized tubes
being perfected, they are to be removed from the treblets, which a gentle
pull will effect; they are then given into the hands of the turner, who
places them in succession on chucks in his lathe and cuts them to their
required lengths.. On one end, within the tube Figure 4, is cemented or.
glued a single coat or ring of vellum, about three or four sixteenths of an
inch in breadth, .or more if required, as at E; at the other end on the outside
is cemented or glued, or otherwise affixed, a substance intended to form a
cylinder of a larger size than the tube on which it is placed, usually termed a
spring, which is fitted to its next size or neighbouring tube wherein the same
slides. This is made with grooves or recesses to receive cloth, as at F, Figure 5..
The vehicle to sustain or carry the cloth may be made of brass or other
metal, or of box or other wood, or of leather; but leather is found more
simple in its application than either brass or wood, and operates with greater
certainty, and is. therefore. preferred. The leather is procured of a thickness
to admit of being turned true and cylindrical, is secured on the tube by
being cemented or glued with wooden or brass pins, as at Figure 4, where it
is nicely fitted by the turner to the next and adjacent tube. To compleat the
construction of the tube at that end, a thin ring of brass or metal is fitted to
the inside immediately under the cylinder or spring, as a support to the spring,
its breadth varying. It may be one eighth, three sixteenths, one fourth, and so.
on to half an inch; if found necessary rings of wood are made, which likewise
answer a similar purpose, and. are frequently used, but are neither so neat
nor so tight. This ring is merely fitted in tight; it may, however, be glued or
secured with pins, or in any other manner, if required. Within the vellum
ring at the other end is affixed a screw ring of brass, as at H, Figure 6.
This is screwed, glued, and pinned; it serves to strengthen that end of the
tube, and from being milled on the edge, becomes an ornament to the instru
ment. It operates also as a check or stop when the glass is being shut or

page_text: closed. The more effectually to prevent friction, which might injure the painted
or otherwise ornamented surfaces of the tube, I augment the thickness of the
cylinder or spring G, Figure 4, on which the tubes slide, just so much as to clear.
the two rings E, Figure 4, and H, Figure 6, viz, the one of vellum and the other
of brass, leaving sufficient windage or space between the inner surface of the
latter and the painted or otherwise ornamented outside surfaces of the sliding
tubes. There is another species of screw ring, as represented at I, Figure 7,
which, instead of screwing into the inside of the tube, affixes to the outside,
and enables the person possessing one of these telescopes to take the same to
pieces at the eye end; the mode before mentioned, as seen at H, Figure 6,
is however the best adapted for general use, and the strongest. By that mode
the telescope will be taken to pieces from the object end. The stops or
diaphragms for contracting the aperture of light are formed of boxwood,
brass, or metal, I usually prefer brass. The cell containing the object glass or
glasses I form of ivory or wood for lightness; I omit the cover usually placed:
at that end for the same reason. The same in some instances is lined with a
thin brass ring, and the counter screw which incloses and secures the glasses
I usually make of brass. The head of the instrument is made also of ivory.
or wood for lightness; boxwood is generally preferred. I have given to this
part of the telescope a new form, which I occasionally vary, paint, gild,'
varnish, and, otherwise ornament. . I have also discontinued the use of the
sliding shutter at the head of the telescope, as it was constantly being out of
repair, and from its being retained gave to the head a clumsy appearance.
I prefer the foregoing method of constructing the cell for and placing the eye
glass and object glass, but the cover and the old shutter alluded to may
nevertheless be applied to these instruments if thought proper. The inner
tubes containing the eye glasses may be constructed after the same manner as
the tubes of the telescopes, namely, of paper and vellum combined with brass
or metal rings or rims, or they may be made wholly of brass; the latter I in
general prefer and for the most part adopt.
.
.
The second part of my Invention consists of the. introduction of an addi-
tional glass in a new manner into telescopes of small size, usually. called
prospect glasses, whereby the extent of view, and also the magnifying power,?
may be varied to a greater degree than by the instruments of this sort now
used; and telescopes constructed upon this principle may be used in theatres
or other public places as opera glasses, and the additional glass is to be so
placed in one of the tubes as to be at or about the centre of the instrument™
when all the tubes of which it is composed are drawn out. This additional or
intermediate glass must be a magnifying glass, properly adapted to the focus

page_text: of the object glass; and it may be either double convex, plano-convex, or
concavo-convex. For viewing prospects or very distant objects, all the tubes
are to be drawn out to a length suited to the eyesight and the distance of
the object. When this telescope is used as an opera glass, the tube in which
the said additional or intermediate glass is fixed is not to be drawn out from
the largest tube, or that which contains the object glass; nor, in case
the instrument consists of more than three tubes, are any of those to be
drawn out which are between the tubo containing the said additional glass
and the tube containing the object glass. The whole length, when all the
tubes are drawn out, may be about six or seven inches. The largest tube of
this instrument being that which contains the object glass, may also be used
as the lower tube of a longer telescope, and thereby expence will be saved to
such persons as may choose to purchase both. The method of applying the
said largest tube to a longer telescope, and removing it to the prospect or
opera glass, is as follows:-
Letter K, Figure 8, in the Drawing hereunto annexed, represents the said
third or largest tube as annexed in the usual way to the screw ring at M of the
long telescope L. This tube is disengaged by unscrewing the joint at M, and
which will be effected by holding one part still and turning the other. When
the tube K is thus removed, apply it to the screw ring at N, Figure 9.