A MODE OF RENDERING TELESCOPES, PERSPECTIVE, PROSPECT, AND OTHER OPTICAL GLASSES, MORE PORTABLE THAN HAS HITHERTO BEEN EXECUTED
Year: 1800

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, DUDLEY
ADAMS, of Fleet Street, in the City of London, Optician, send greeting.
WHEREAS His most Excellent Majesty King George the Third, by His
Royal Letters Patent under the Great Seal of Great Britain, bearing date
at Westminster, the Thirtieth day of May, in the fortieth year of His reign,
did give and grant unto me, the said Dudley Adams, my exors, admiors, 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 Great
Britain called England, the Dominion of Wales, and the Town of Berwick-
upon-Tweed, my Invention of "A MODE OF RENDERING TELESCOPES, PERSPECTIVE,
PROSPECT, AND OTHER OPTICAL GLASSES, MORE PORTABLE THAN HAS HITHERTO BEEN
EXECUTED;" 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 one calendar month 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.
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 explain and

page_text: describe the nature of my said Invention and the manner in which the same
is to be performed, by the Drawings, references, and explanations herein
contained and set forth, that is to say:-
The principle and utility on which my new Invention on telescopes, per-
spective, prospect, and other optical glasses is, founded is, in rendering them by
this new construction considerably more portable than they have hitherto been
made. In order to produce the peculiar degree of portability that has been
effected, it was found expedient to adopt a new species of spring that would
from its principle and construction occupy the least possible space, and at
the same time render the telescopes to which it was applied strong and
steady when drawn out; this was the more necessary as, according to the
new construction, the number of joints or tubes would be augmented con-
siderably beyond the number hitherto employed. It was necessary also to
devise some means by which the several glasses applied to the eye ends of
telescopes should acquire their true positions and distances when the joints
or tubes were drawn out after having been compressed into a small space,
and the same be retained in every situation wherein they might be placed
by the observer during the time the telescope was being adjusted for use.
REFERENCE TO THE DRAWING.
Fig. 1 A represents the form and construction of the spring; it consists
of a thin piece of metal tube turned in a lathe strictly true and cylindrical,
and to fit the inside of the drawer or tube in which it is intended to slide. It
is then slit down from the open end in two, three, four, or moro places to give
it clasticity; this latter circumstance is not however absolutely necessary. The
dotted lines at B represent the under side of the spring perforated, in which
a screw is cut, of the size to screw on the end of the tube at C, Fig. 2, and
inade fast there.
This inverted cylindrical spring, simple as it is in its construction, affords
all the advantages necessary; it occupies less space than the springs hitherto
adopted, and by that means, admits of more drawers, tubes, or joints being
added than could, according to the former mode, be used or applied within.
the same space; by its cylindrical form, that strength and steadiness is obtained
which is so essential to the constructing a good telescope with drawers; it
preserves the axis thercof as one uninterrupted line in every position of the
drawers, whether they are drawn out to the fullest extent, or returned in part
into their several tubes. It is also of superior advantage and the best adapted
to the construction of plated telescopes, whether plated in gold or silver, or
whether the drawers or tubes are lacquer'd, painted, or japanned, &c.; as

page_text: by its action and principle all pressure and friction on their polished, plated,
or painted surfaces may be obviated, and the possibility of those surfaces
being rubbed, scratched, or worn thereby, totally prevented. Fig. 3 represents
the tube C, with the spring thereon at D; E represents the tube in which it
slides.
The second part of the Invention is effected in the following manner :-
Fig. 4 C represents the tube called the eye tube, or that which is placed
next the eye when the telescope is being used; A, the spring thereon; H and
I, two tubes that are made to slide into the interior of the tube C; E, a broad
circular plate, shoulder, or flanch. To explain the action and principle of
the tubes H and I more fully, another Figure, viz, Fig. 5, has been given;
C represents the tube to be placed next the eye; a the new inverted cylin-
drical spring thereon; D, the next tube in which the said spring slides,
provided also with its spring a, which slides in the third tube E. The first
and second glasses are contained in the eye tube C, and are represented by
dotted lines G, G. The third and fourth glass are inserted in the tube H,
at b, c.
These tubes, as have been mentioned, are made to slide into the
interior of the eye tube C when the instrument is closed, but when the tubes
are drawn out they will have nearly the effect as represented, for when the
tubes C, D, and E are drawn out, the flanch F will strike against the end of
the tube D, and by that means the two tubes H and I will also be drawn out,
and will retain their présent position until all the tubes are nearly closed; for
it is not until the flanch F reaches one of the last tubes, that the two tubes
Hand I will be forced into the tube C. The glasses, therefore, contained
in them will acquire and retain their true distances while being used.
The advantages of this part of the Invention need not be enlarged upon,
as it will appear obvious to every one who considers the subject, that by means
thereof, together with the new spring, the utmost portability in telescopes
may be effected, and their length, in consequence, be considerably extended
beyond what is usually adopted, if necessary.
The same degree of portability and any degree of length may be obtained
by the addition of three, four, or more tubes in the place of the two already
mentioned, and the tube containing the first and second glasses might be
constructed after the same manner, viz, to consist of two, three, or more
tubes, and made to slide one within the other; and in some instances where
the telescopes are very long, one tube might be made, perhaps, to answer the
purpose. These and other similar modes, might hereafter be adopted without
altering the principle of this Invention, which establishes a rule whereby the
several glasses at the eye ends of telescopes may, from the manner.in which

page_text: they are placed, be brought near to each other, and afterwards placed at their
proper distances without inconvenience or prejudice to the telescope. Of the
many modes that have been tried, and named herein, the particular one
adopted has been preferred; it is the most simple, and it moreover possesses all
the advantages required.
In witness whereof, I have hereunto set my hand and seal; this Twenty-
first day of June, in the fortieth year of the reign of our Sovereign
Lord George the Third, and in the year of our Lord One thousand
eight hundréd.