New ROLLING PARALLEL RULER, EITHER WITH OR WITHOUT SCALES, SLIDING PEN, AND PENCIL, FOR THE PURPOSES OF DRAWING AND DIVIDING, NOT ONLY PARALLEL LINES, BUT ALSO PERPENDICULARS, CIRCLES, & ANGLES OF ALL DEGREES WHICH CAN BE MEASURED, DIVIDED, AND DETERMINED AT FIRST SIGHT, AND ALL GEOMETRICAL PROBLEMS DRAWN AND PLANS LAID DOWN IN PERSPECTIVE. THEREBY WITH THE GREATEST FACILITY, WHICH, BY REPEATED TRIALS AND EXPERIMENTS, HAD BEEN FOUND TO ANSWER MUCH BETTER THAN ANY OTHER INSTRUMENT IN USE
Year: 1771

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, ANTHONY
GEORGE ECKHARDT, of London, Gentleman, sends greeting.
WHEREAS the said Anthony George Eckhardt did, by his Petition, humbly
represent unto His most Excellent Majesty King George the Third that he
had, by long study, pains, and expence found out and invented "A New
ROLLING PARALLEL RULER, EITHER WITH OR WITHOUT SCALES, SLIDING PEN, AND
PENCIL, FOR THE PURPOSES OF DRAWING AND DIVIDING, NOT ONLY PARALLEL LINES,
BUT ALSO PERPENDICULARS, CIRCLES, & ANGLES OF ALL DEGREES WHICH CAN BE
MEASURED, DIVIDED, AND DETERMINED AT FIRST SIGHT, AND ALL GEOMETRICAL
PROBLEMS DRAWN AND PLANS LAID DOWN IN PERSPECTIVE. THEREBY WITH THE
GREATEST FACILITY, WHICH, BY REPEATED TRIALS AND EXPERIMENTS, HAD BEEN
FOUND TO ANSWER MUCH BETTER THAN ANY OTHER INSTRUMENT IN USE," and
thereby prayed His Majesty to grant unto him. His Letters Patent for the
sole making and vending of the said Parallel Ruler; and His said Majesty,
being graciously pleased to condescend to his request, did; by His Royal
Letters Patent, bearing date at Westminster, the Twenty-third day of March,
in the eleventh year of His reign, give and grant unto the said Anthony
George Eckhardt, his executors, administrators, and assigns, especial licence,
full power, sole priviledge and authority, that he, the said Anthony George
Eckhardt, his executors, administrators, and assigns, and every of them, by
himself and themselves, or by his and their deputy or deputies, servants or
agents, or such others as he, the said Anthony George Eckhardt, his executors,
administrators, or assigns, shall at any time agree with, and no others, from
time to time and at all times thereafter, during the term of fourteen years
therein expressed; should and lawfully might make, use, exercise, and vend his

page_text: said Invention, within that part of His Majesty's Kingdom of Great Britain
called England, His Dominion of Wales, and Town of Berwick-upon-Tweed,
and also in His Colonies and Plantations abroad, in such manner as to him,
the said Anthony George Eckhardt, his executors, administrators, and assigns,
or any of them, should in their discretion seem meet, and that he, the said
Anthony George Eckhardt, his executors, admors, and assigns, should and
lawfully might have and enjoy the whole profit, benefit, commodity, and advan-
tage from time to time coming, growing, accruing, and arising by reason of the
said Invention, for and during the term of years therein mentioned; to have,
hold, exercise, and enjoy the said licence, powers, priviledges, and advantages
therein-before granted or mentioned to be granted unto the said Anthony George
Eckhardt, his executors, administrators, and assigns, for and during and unto
the full end and term of fourteen years from the date of the said Letters
Patent next and immediately ensuing and fully to be compleat and ended,
according to the Statute in such case made and provided; in which said
Letters Patent is contained a proviso that if I, the said Anthony George
Eckhardt, shall not particularly describe and ascertain the nature of his said
Invention, and in what manner the same is to be performed, by an instrument
in writing under his hand and seal, and cause the same to be inrolled in the
High Court of Chancery within four calendar months next and immediately
after the date of the said Letters Patent, that then the said Letters Patent,
and all libertys and advantages whatsoever thereby granted, shall utterly cease,
determine, and become void, "anything therein-before contained to the contrary
thereof in anywise notwithstanding, as in and by the said Letters Patent,
relation being thereunto had, more fully and at large may appear.
NOW KNOW YE, that he, the said Anthony George Eckhardt, in pur-
suance of the said recited provisoe, doth, by this Instrument in writing unde
his hand and seal, particularly describe and ascertain the nature of his said
Invention, and the manner in which the same is to be performed, in manner
following (that is to say):
First, provide a flat solid substance, of wood or metal, in the usual form
generally adapted by the mathematical instrument makers for making flat
rulers or scales. And, for compleating and perfecting the same into a rolling
parallel ruler, as it may be required for the different purposes to which the
same is applicable, as mentioned in the said in part recited Letters Patent, the
said Anthony George Eckhardt hath caused several Drawings thereof, and of
its different parts and constructions, to be made and annexed to these Presents,
beginning from the effect of the mere parallel rule, and rising by small degrees
of improvement to the most perfect state of the Invention, which must

page_text: necessarily be divided into a variety of different classes, according to the
different uses it may be required to be applied to, which said new-invented
ruler, and the several Drawings thereof hereunto annexed are herein-after
more particularly mentioned and described (that is to say):-
A, No. 1, is a flat ruler or scale for drawing parallel lines with much greater
facility than by the parallel ruler; and through the center thereof, in the whole
length, is preserved a moulding, marked letter B, of at least double the
thickness of the flat part, through which a center is perforated to admit an
axis of steel to be placed therein, and at each end of the axis is to be fixed a
wheel, marked C, C, of wood or metal, for the scale to roll freely upon, as
described in the Drawing: and this is all that is required for the ruler A,
No. 1.
A, No. 2, is a ruler for the same purpose, and in its construction similar in
all respects to the other, with this addition, that the two wheels C, C, and the
feathered edges D, D, are graduated in inches and their parts, the scales E, E,
annexed to the two wheels C, C, having each a small index F, F, to determine
the distance of the parallel lines: and this compleats the ruler A, No. 2,
according to the Drawing. But as these two rulers, and these two only, are
capable of being constructed with a rolling cillinder, marked G in the rulers B,
No. 1 and 2, instead of a moulding and axis, the distinction between them is
described in the next.
B, No. 1 and 2, are parallel rulers, with rolling cillinders for drawing,
dividing, and determining at sight the distance of parallel lines, and determin-
ing perpendiculars; and when the flat substance, as first mentioned, is provided,
let a cilinder of wood or metal, marked G, be prepared with two pivots, one
at each end, of a given thickness, sufficient for the scale to roll freely upon, for
which purpose a cavity must be made in the scale to introduce it in the center
of the length of the flat part, the two pivots being artistly fixed and inclosed in
brass shoulders or sockets, marked H, H, to roll freely in. This is the only
difference in the particular construction of these rulers from the other two
above described.
C, No. 3, is a ruler for drawing and dividing both parallel lines and perpen-
diculars, as well as determining their respective distances, and is similar to A,
No. 2, with this difference, that the two graduated feathered edges D, D, are
to be made of brass for the convenience of fixing thereon a sliding pen, pencil,
and point, with their sliding spring, as described in the Drawings by the
letters I, K, L, M.
D, No. 4, is a ruler for drawing and dividing parallel lines, perpendiculars,
and circles, and for determining angles of all degrees, and is similar in all

page_text: respects to the last, with the addition of a moving circular graduated plate in
the center, as described by Figure N, in C, No. 3, which is divided into parts
that demonstrate the space the rule may have passed over in inches and parts
of inches, and for determining angles of all degrees. This circular plate
receiving its motion from a pinion O, fixed in the axis that runs through the
center of the ruler, and playing in the teeth of a cantered wheel N, being the
under part of the circular plate; and to this is further added, on the under
part of the scale, two folding brass arms p, p, let into and made flush with the
solid part of the rule, for the purpose, each of them, to serve as a center occa-
sionally to produce circles means of this rule, each having its own point for
that purpose; and.when either of these are to be used a provision is made, as
described in the Drawing, for freeing one of the wheels from the square
in which it was previously fastened at the end of the axis, that, instead of
moving with it, it may now be at liberty, and turn retrograde to the other,
for the particular construction of which see the Drawing Q, Q. And the
circular plate above described may also be constructed with a screw and teeth,
as in the Figure R, for performing the whole of all the preceding particulars
in every respect, with the addition to the last-mentioned ruler of a small
mutation for reducing geometry into perspective: shift or move one of the two
wheels, and place in lieu thereof a larger or smaller wheel of the same con-
struction, of which a number are to be provided of different diameters than
that which is permanent, for the purpose of laying down plans in geometry or
perspective.
And lastly, as a further improvement to the said ruler, taken in the aggregate,
it might with advantage be made to consist of two, instead of one axis or cilinder;
or, in lieu thereof, four friction wheels might be added to the four corners on
the under part of each ruler; and, for further accuracy in the use of the scales,
Nonus's might be added to them.
In witness whereof, the said Anthony George Eckhardt hath hereunto set
his hand and seal, this Twenty-second day of July, in the eleventh year
of the reign of our Sovereign Lord George the Third, by the grace of
God of Great Britain, France, and Ireland King, Defender of the
Faith, and so forth, and in the year of our Lord One thousand seven
hundred and seventy-one..
A. G. (L.s.) ECKHARDT. 35
Sealed and delivered (being first duly
stampt) in the presence of
SAMUEL SMITH.
GEO. BURSEY.