IMPROVED MILITARY AND NAVAL TELESCOPE
Year: 1799

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CATER
RAND, of Lewis, in the County of Sussex, send greeting.
WHEREAS His most Excellent Majesty King George the Third, by His
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Twenty-sixth day of January, in the thirty-ninth year of His
reign, did give and grant unto me, the said Cater Rand, my executors,
administrators, and assigns, His special licence, full power, sole privilege and
authority, that I, the said Cater Rand, my executors, administrators, and
assigns, during the term of years therein expressed, should and lawfully
might make, use, exercise, and vend, within England and Wales, and the
Town of Berwick-upon-Tweed, my "IMPROVED MILITARY AND NAVAL TELESCOPE,"
and in which said Letters Patent there is contained a proviso obliging me, the said
Cater Rand, under my hand and seal, to cause a particular description of the
nature of my Invention, and in what manner the same is to be performed, to be
inrolled in His Majesty's High Court of Chancery within six 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.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Cater Rand, do hereby declare that my said Invention of an improved
military and naval telescope, and new invented micrometer thereto, adapted for
ascertaining distances, and the size and extention of objects, is described in the
plan hereunto annexed, and the following description thereof:-

page_text: °
The telescope is made refracting, acliromatic, or reflecting, and the micro-
meter has four parallel hairs or wires fitted to silver, brass, copper, or other
well contrived converging and diverging plates, two of which parallel hairs or
wires have a perinanent and fixed value, and the other two are valued in pro-
portion to their degree of divergency, measured in parts of a great circle, and
are put into motion, governed, and regulated by a proper mechanical move-
ment, which at one and the same time acts upon the diverging or converging
paralel hairs or wires, and gives a vertical motion to a scale by the side of a
stationary verniers or nonius index, whose respective divisions are calculated
to measure the minutes of a degree of a great circle, the vernier or nonius at
the same time performing its proper office, subdivides the minutes of the
moving scale into tenths, equal in value to 6" or seconds of a great circle,
read off from the bottom towards the top of the index scale placed to the right
of the micrometer scale, immediately opposite to which is placed a small lens
of sufficient magnifying power for reading off the divisions, and easily directed
to its proper focus to suit the eye of the observer.
The whole of the above apparatus (except the lens which is fixed before the
index at the distance of half an inch or thereabouts, according to its focal
distance, is framed together and properly fitted on the eye tube of the telescope,
which being brought to its proper focus in the usual way for viewing objects,
is then fitted for observation for measuring the angle subtended by any object
for finding its distance by a single observation, if its licight or size be known,
or by two observations, and the intermediate distance, when neither distance,
size, or height are known, but both required, in manner following:
If the angle subtended by any object be sought in the table of distances,
placed on the outside tube of every telescope, and its corresponding tabular
number be multiplied by the known size or height of the object in any
measure, the distance of the object will be found in the same measure. If the
height be required from the known distance, the tabular nuimber corresponding
to the angle as before divided by the distance will give tlie lieight or size, and
this by one observation. If the distance and size, or height of an object, or
both required, when neither is known, the intermediate distance paced or
measured between two stations, multiplied into the larger angle, subtended by
the object, and that product divided by the difference of the angles taken at
each station or place of observation, will give the distance from the farthest
station or place of observation, from which, if the intermediate distance be
taken, it will leave the distance from the nearest place of observation to the
object dividing the tabular number as before, by either distance corresponding
with the subtending angle, will give the size or height of the object; hence at

page_text: one station or place of observation the distance of an object may be found if
the angle subtended by that object be truly taken, and the size or height be
known, and the height or size of the distance be known; hence also, from
two stations, or from two places of observation, and the known intermediate
distance, both the distance and height, or size of an object, may be found
when neither of them is known.
Fig. 1, general view of the telescope, partly drawn out to shew the tubes
micrometer part, table of dist. &c. Fig. 2 shews all the parts of the micro-
meter as they appear adjusted for observation, fixed in the eye tube of the
telescope and facing the eye glass. Fig. 3 shews the back part of the micro-
meter towards the object glass. A, B, C, D, E, F, G, H, I, K, shows the
Several parts forming the principles and value of the micrometer as adapted to
the patent telescope, the angle subtended by an object being found by the
diverging, converging, or fixed value of the parallel plates, hairs, or wires
a, b, c, in center of Fig. 2, a being double, although appearing as one. A shews
the micrometrical scale to find the value of the subtending angle, assisted by B,
the vernier or nonius, fixed opposite and parallel to the moving scale put into
motion by the double threaded male screw I passing through the picce E, and
through the female screw piece F into the piece affix'd to plate D, as it
appears at , Fig. 2. C and D are similar plates; part of C in Fig. 2 only can
be seen, as at c; to these plates the parallel hairs or wires are fixed. Gand H
are two brass plates fixed to similar ones to form a groove for the micrometer
plates, C, D, to move in and to keep them true and steady. K is a small lens
to read off the sub-divisions on the micrometer scale.

page_text: AND BE IT REMEMBERED, that on the same Twenty-third day of July,
in the year above mentioned, the aforesaid Cater Rand came before our Lord
the King in His Chancery, and acknowledged the Specification aforesaid, and
all and every thing 'therein contained, in form above written. And also the
Specification aforesaid was stamped according to the tenor of the Statute in
that case made and provided.
Inrolled the same Twenty-third day of July, in the year above written.