IMPROVEMENTS IN OBTAINING MECHANICAL POWER, WHICH ARE ALSO APPLICABLE FOR OBTAINING RAPID MOTION
Year: 1841

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
PETRIE, late of Croydon, in the County of Surrey, but now of Conduit Street,
London, in the County of Middlesex, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent under the Great Seal of Great Britain, bearing date at Westminster,
the Nineteenth day of June, in the fourth year of Her reign, did, for Herself,
Her heirs and successors, give and grant unto me, the said William Petrie,
Her especial licence that I, the said William Petrie, my exors, adññors, and
assigns, or such others as I, the said William Petrie, my exors, admors, and
assigns, should at any time agree with, and no others, from time to time and at.
all times during the term of years therein expressed, should and lawfully
might use, exercise, and vend, within England, Wales, and the Town of
Berwick-upon-Tweed, and in the Islands of Jersey, Guernsey, Alderney, Sark,
and Man, and also in all Her Majesty's Colonies and Plantations abroad, my.
Invention of "IMPROVEMENTS IN OBTAINING MECHANICAL POWER, WHICH ARE ALSO
APPLICABLE FOR OBTAINING RAPID MOTION;" in which said Letters Patent there is
contained a proviso obliging me, the said William Petrie, 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 to cause the same to be enrolled in Her 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, reference being
thereunto had, will more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
William Petrie, do hereby declare that the nature of my said Invention, and the
manner in which the same is to be performed, is described and ascertained
as follows, that is to say:-
My improvements consist in a system of internal differential gearing, which
is applicable wherever cranes, crabs, windlasses, capstans, or such like machines
are required. The following is a description of the said gearing, reference
being made by letters to the annexed Diagrams.
On the terminating crank (C) of an axle (A) are placed two toothed wheels
(O and P) fastened firmly together, or made in one piece, both being free to
revolve together on the crank; one of these wheels (P) is larger than the
other (O). I prefer putting the larger one at the further extremity of the
crank. The small wheel (0) revolves in a fixed internal toothed wheel or
circle (Q) supported by its exterior periphery, and which has its centre in a
line with the axle (A), and its interior radius equal to that of the small
crank wheel (O) added to the length of the crank. The larger wheel (P)
revolves in another internal toothed wheel (R), fixed by its centre at the
extremity of a revolveable axle (B) which lies beyond the crank in a straight
line with the cranked axle (A), so that the internal wheel (R) lies flat against
but does not quite touch the fixed internal wheel (Q); the internal radius of
this wheel (R) (which I name the resistance wheel) is equal to that of the large
crank wheel (P) added to the length of the crank. The teeth of the wheels
should be as short as convenience will allow, but it is unnecessary to describe
the shape of the teeth, or means of fastening the wheels on to the crank, or the
bearings of the axle," or the supporting framework, as their construction is
well known to engineers. An ordinary barrel (D) may be fixed on the axle
(B) for winding up a rope or chain, and a winch (E) may be attached to the
cranked axle (A); if the nature of the work requires these additions, such as
when the machine is applied to cranes. Now, if the cranked axle be made to
revolve, the resistance wheel will revolve with greater power, and consequently
slower, provided that double the length of the crank multiplied by the dif-
ference between the diameter of the small and large crank wheels be less than
the diameter of the resistance wheel multiplied by the diameter of the small
crank wheel, as that gives the proportion of the force to be applied 'to-balance
any given resistance, independently of friction and of power gained by the
relative sizes of the barrel (D) and winch (E), consequently the shorter the
crank and the nearer to equality the two crank wheels' are the greater is the
power of the machine. It is not necessary that the barrel (D) and its axle
should be on the side of the wheels opposite to that on which the power is

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
PETRIE, late of Croydon, in the County of Surrey, but now of Conduit Street,
in the County of Middlesex, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent under the Great Seal of Great Britain, bearing date at Westminster,
the Ninteenth day of June, in the fourth year of Her reign, did, for Herself,
Her heirs and successors, give and grant unto me, the said William Petrie,
Her especial licence, that I, the said William Petrie, my exors, admors,
and assigns, or such others as I, the said William Petrie, my exors, adiñors,
and assigns, should at any time agree with, and no others, from time to time
and at all times during the term of years therein expressed, should and law-
fully might make, use, exercise, and vend, within England, Wales, and the Town
of Berwick-upon-Tweed, and in the Islands of Jersey, Guernsey, Alderney,
Sark, and Man, and also in all Her Majesty's Colonies and Plantations abroad,
my Invention of Improvements in Obtaining Mechanical Power, which are also
applicable for Obtaining Rapid Motion; and whereas I, the said William
Petrie, in pursuance of a proviso in the said in part recited Letters Patent
contained, have caused a particular description of the nature of my said Inven-
tion, and in what manner the same is to be performed, by an instrument in
writing under my hand and seal, to be inrolled in Her said Majesty's High
Court of Chancery on the Eighteenth day of this instant December; and
whereas I, the said William Petrie, am desirous, for good and sufficient reasons
herein-after mentioned, to enter a Disclaimer of that part of the title of my said
Invention herein-after next mentioned, and have obtained leave of Her
Majesty's Attorney-General, certified by his fiat and signature according to the
form of the Statute in such case made and provided.
KNOW YE therefore that I, the said William Petrie, do hereby disclaim the
following part of the title of my said Invention, that is to say:-
I disclaim the words "which are also applicable for Obtaining Rapid Motion."
And I, the said William Petric, do also hereby declare that my reasons for
making and entering the above Disclaimer are as follows, that is to say, that
the machinery for which I have obtained the Letters Patent is not in most
cases found to be applicable to the obtaining rapid motion; and I; the said
William Petrie, do hereby further declare that the above Disclaimer is not such

page_text: This is to certify, that the above-named William Petric has applied to me
for leave to enter with you the above-written Disclaimer of part of the title of a
certain Invention for which Letters Patent were duly granted to him under the
Great Seal of Great Britain, dated at Westminster, the Nineteenth day of
June, One thousand eight hundred and forty-one; and having considered the
above application, and no objection having been made to the same, I have
accordingly granted leave to the said William Petrie to file his said Disclaimer,
pursuant to the Statute passed in the fifth and sixth years of the reign of King
William the Fourth, entitled An Act to amend the Law touching Letters
Patent for Inventions.