CERTAIN IMPROVEMENTS IN THE CON- STRUCTION OF DIOPTRIC TELESCOPES
Year: 1815

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JEAN
RONDONI, of Oxford Street, in the County of Middlesex, Gentleman, send.
greeting.
WHEREAS His most Excellent Majesty King George the Third did, by
His Letters Patent under the Great Seal of the United Kingdom of Great.
Britain and Ireland, bearing date at Westminster, the Twentieth day of
January, in the fifty-fifth year of His reign, give and grant unto me, the said
Jean Rondoni, my exors, adñiors, and assigns, His especial licence, full power,
sole privilege and authority, that I, the said Jean Rondoni, my exors,
adiiors, and assigns, during the term of years therein mentioned, should and
lawfully might make, use, exercise, and vend, within England, Wales, and.
the Town of Berwick-upon-Tweed, an Invention communicated to him by
a certain Foreigner residing abroad, of "CERTAIN IMPROVEMENTS IN THE CON-
STRUCTION OF DIOPTRIC TELESCOPES;" in which said Letters Patent there is
contained a proviso that if I, the said Jean Rondoni, shall not particularly
describe and ascertain the nature of the said Invention, and in what manner
the same is to be performed, by an instrument in writing under my hand and
seal, and cause the same to be inrolled in His Majesty's High Court of
Chancery within six calendar months next and immediately after the date
of the said Letters Patent, that then the said Letters Patent, and all liberties
and advantages whatsoever thereby granted, shall utterly cease, determine,
and become void, as in and by the same, (relation being thereunto had), may
more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Jean Rondoni, do hereby declare that the nature of the said Invention, and
manner in which the same is to be performed, are particularly described and
ascertained in manner following, that is to say :-
t. It doth consist in the varying the magnifying power of dioptric telescopes
by my improvements in the same for the well known benefit and advantage
thereby derived, and the manner of performing the same is set forth herein-
after and by the Drawings hereunto annexed.
And firstly, with regard to varying the magnifying power of telescopes,
when the eye glasses of the same are to be concave, or bear a diminishing
power, I do form the eye part of two concave glasses, placing one in the side
or tube nearest the eye, and the other in the next or second or third or other
tube from the eye, as the power of the glasses or other circumstances may
require, by which means I am enabled to bring near together or divide
apart my said two concave glasses, and as the same are brought nearer
together the magnifying power increases, and as they are divided apart the
contrary.
And secondly, with regard to varying the magnifying power of telescopes
of the usual construction, with four convex glasses in the eye part, I'do
construct them in such manner that the third and fourth glasses-from-the-eye
may be moved further from or nearer to the eye by the means and after the
manner following:-
1.
Figure 1 in the said Drawings represents à longitudonal section of the eye
part of a telescope, having four convex glasses in the same; and supposed to be
placed at the usual relative distances from each other, having regard to their
several powers. a a¹, a a² represents the external tube of the said eye part,
having therein the two slits or openings cc, cc, one of which openings.is
again represented at c c³.
Fig. 2. bb, bb, is a tube containing the two first eye glasses, No. 1 and 2,
and the stop d; similar in all respects to tubes in the like situation in common
use, and therefore forming no part of the said improvements. 5, 6, 5, 6, is a
tube carrying on it the glass 3, and 8, '8, is a welt or protuberance formed
thereon so as to touch and press on the internal surface of the tube a a', a a
7, 7, is another protuberance on the internal surface of the tube a a', a a³
touching and pressing on the external surface of the tube 5, 6, 5, 6. 9, 9,
tinted red, is another protuberance in the internal surface of the tube 5, 6, 5, 6;
and at 6, 6, tinted blue, is a ring screwed into the same tube and forming
another protuberance internally and externally. 12, 13, 12, 13, is a tube, part
of which passes freely within the tube 5, 6, 5, 6, and carries within it the

page_text: glass 4; and 14, 14, 14, 14, tinted red, is a stop perforated at 17, and supposed
to lie at the proper situation usual for a stóp between the glasses 3 and 4; and
in the external surface of the tube 12, 13, 12, 13, at 11, 11, is a thread or
screw cut on the same; and 10, 10, tinted red, is a stop capable of being
screwed backward and forwards thereon, and allow the tube 12, 13, 12, 13,
to pass farther into the tube 5, 6, 5, 6, on the contrary, and regulate or
adjust the proper distance between the glasses 3 and 4, whilst in the usual
situation. 15, 15, and 16, 16, are two bearing pieces pressing against the
tube a a, a a, and causing the tube 12, 13, 12, 13, to pass steadily up and
down the same. And I do (supposing the glasses 1, 2, 3, 4, to be at their
proper relative distances with regard to the power thereof, or other requisites,
according to the usual formation of telescopes) by pressing on the tube 5, 6, 5, 6,
at the aperture cc³, cc², force the same forward, and cause the glass 3 to come
nearer to the glass 4, and further from the glasses 1 and 2, and thereby gra-
dually increase the magnifying power of the telescope, and when thereby the
stop 9, 9, has come in contact with 10, 10, the tube 12, 13, 12, 13, and the
glass 4 in the same, are passed forwards in the same direction, and with the
glass 3, by which the magnifying power of the said telescope is still increased;
and as either of the said movements and increase of magnifying power takes
place, the whole eye-part of the telescope must be drawn out with the tube
a a', a a², to increase the distance from the object glass, and in returning the
same to or towards their original situation the contrary. And in adapting my
said improvement relative to telescopes with convex eye glasses, where the num-
ber of tubes or slides is increased for the sake of portability or compactness, I
do form the part of tube 12, 13, 12, 13, between the bearing parts 16, 16, and
15, 15, much shorter and fit to the internal diameter of the second tube from
the eye, and do form the rest of my before-described alterations in the first
tube next the eye. And, moreover, my said improvements may be varied
and adapted with regard to dimension and formation, and that the moveability
of the glasses may be done by means of wheel and rack work, or screw and
nut, or other well-known means not required here to be particularized, and
which any competent workman in works of this and the like nature can devise
and execute.
In witness whereof, I, the said Jean Rondoni, have hereunto set my
hand and seal, the Fourteenth day of July, in the year of our Lord
One thousand eight hundred and fifteen.
JEAN (L.s.) RONDONI.

page_text: AND BE IT REMEMBERED, that on the Fourteenth day of July, in the
year of our Lord 1815, the aforesaid Jean Rondoni came before our said Lord
the King in His Chancery, and acknowleged the Specification aforesaid,
and all and every thing therein contained and specified, in form above written,
thro' the interpretation of Leger Didot. And also the Specification aforesaid
was stampt according to the tenor of the Statute made for that purpose.
Inrolled the Fifteenth day of July, in the year of our Lord One thou-
sand eight hundred and fifteen.