IMPROVEMENTS IN INSTRUMENTS FOR ASCERTAINING THE SPEED OF MACHINERY
Year: 1867

page_text: LETTERS PATENT to John Benjamin Dancer, of No. 43, Cross Street, in
the City of Manchester, in the County of Lancaster, Mathematical
Instrument Maker, for the Invention of "IMPROVEMENTS IN INSTRUMENTS
Sealed the 21st June 1867, and dated the 14th March. 1867.
PROVISIONAL SPECIFICATION left by the said John Benjamin Dancer at
the Office of the Commissioners of Patents, with his Petition, on the
14th March 1867.
.
I, JOHN BENJAMIN DANCER, of No. 43, Cross Street, in the City of
Manchester, in the County of Lancaster, Mathematical Instrument Maker,
do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN INSTRUMENTS FOR ASCERTAINING THE SPEED OF MACHINERY," to be as
follows:-
My Invention consists of a wheel or roller of known diameter, which is
connected with a train of wheels contained in a box or other suitable case,
which wheels when in motion cause certain hands or indices to rotate over
graduated dials placed on the box or other suitable case. By the aid of a
watch and a reference to the position of the hands or indices over the graduated
dials the number of revolutions made by the wheel or roller in a given time
can be ascertained when it is placed in connection with the machinery required
to be measured.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Benjamin Dancer in the Great Seal Patent Office on
the 21st August 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
BENJAMIN DANCER, of No. 43, Cross Street, in the City of Manchester, in the
County of Lancaster, Mathematical Instrument Maker, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fourteenth day of March, in the year of our
Lord One thousand eight hundred and sixty-seven, in the thirtieth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said John Benjamin Dancer, Her special license that I, the said
John Benjamin Dancer, my executors, administrators, and assigns, or such
others as I, the said John Benjamin Dancer, my executors, administrators,
and assigns, should at any time agree with, and no others, from time to
time and at all times thereafter during the term therein expressed, should
and lawfully might make, use, exercise, and vend, within the United
Kingdom of Great Britain and Ireland, the Channel Islands, and Isle of
Man, an Invention for "IMPROVEMENTS IN INSTRUMENTS FOR ASCERTAINING THE.
SPEED OF MACHINERY," upon the condition (amongst others) that I, the said John
Benjamin Dancer, my executors or administrators, by an instrument in writing
under my, or their, or one of their hands and seals, should particularly describe
and ascertain the nature of the said Invention, and in what manner the
same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately after
the date of the said Letters Patent.
NOW KNOW YE, that I, the said John Benjamin Dancer, do hereby
declare the nature of my said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and
following statement (that is to say) :-
the
My Invention consists of a wheel or roller of known diameter, which is
connected with a train of wheels contained in a box or other suitable case,
which wheels when in motion cause certain hands or indices to rotate over a
graduated dial or dials placed on the box or other suitable case. By the aid
of a watch and a reference to the position of the hands or indices over the
graduated dial or dials the number of revolutions made by the wheel or roller
in a given time can be ascertained when it is placed in connection with the
machinery the speed of which is required to be ascertained.
And in order that my Invention may be fully understood and.readily carried

page_text: into operation I will proceed to describe the accompanying Sheet of Drawings,
reference being had to the figures and letters marked thereon.
Figure 1 is a plan of the instrument complete; Figure 2 is a plan with
the dial removed to show the internal arrangement; Figure 3 is a vertical
section and Figure 4 is an elevation of the instrument showing the mode
of applying it to the shaft or other article the speed of which is to be
ascertained.
The instrument consists of the upper case a and bottom plate a', to which
are fixed bearings for the axle b, on which is cut a screw b gearing into the
wheel c having fifty teeth; this wheel is fixed on the spindle d, to the upper
end of which is fixed the index or finger e rotating over the graduated dial f
like the minute hand of a watch. To the wheel c is fixed the single tooth c',
which gears into the pinion g and moves it round for one tooth at every entire
revolution of the wheel c. The pinion g is fixed to the same axle as the
pinion h which gears into the wheel i, having the same number of teeth, but
being rather larger than the wheel c. The boss of the wheel i is hollow, and
to it is fixed the index j corresponding to the hour hand of a watch. The
retaining catch k taking into the wheel i is to hold the wheel when it has been
moved one tooth. To the axle b is fixed the friction wheel or roller 62; this
wheel or roller may be provided with an india-rubber band to increase the
friction, and it can be easily removed and replaced by another wheel or roller
of different diameter if required to suit the diameter of the shaft or other
article the speed of which is to be ascertained.
The mode of operation is as follows:-When the instrument is to be used
both the indices e and j should be pointing to 50 on the graduated dial, as shewn
in Figure 1. The friction wheel 3 is then held in contact with the shaft or
other article to be counted marked in Figure 4. If the roller b³ and the
article are of the same diameters it is evident that they will both rotate at the
same speed. In order to steady the instrument while in use I have applied the
adjustable guide m to the case a', which guide bears upon the shaft or other
revolving article. As soon as the roller is applied to the shaft / the operator
must observe the exact time by a watch or other timekeeper; as the roller 62
revolves every fifty revolutions thereof will cause the index e to travel once
round the dial and to move the index jone division of the inner graduated
circle, consequently when the roller 62 is moved out of contact with the shaft /
the position of the indices indicates the number of revolutions that have been
made.
The instrument shews the number of revolutions in a given time without
any calculations when the roller is of the same diameter as the shaft 7, but

page_text: if the diameters of the roller 6 and shaft to be counted are not alike, then
the apparent speed shewn by the instrument will require a correction depending
on the proportion of the diameters of the parts in contact; for example, if
the wheel or roller & be 2 inches in diameter and the rotating part of the
machinery with which it is held in contact be 4 inches in diameter the speed
as shown on the dial would be double that of the real or required speed. On
the contrary, if the part of the machinery in contact with the wheel or roller b
be one inch in diameter then the speed shewn on the dial would be only half
the true speed. There is a contrivance for throwing the wheel or roller b²
out of gear at any required moment to prevent the momentum which the
wheel or roller 63 acquires from being registered by the instrument after the
instrument is removed from contact with the part of the machinery in motion.
This contrivance consists in raising the wheel c out of gear with the screw b
by the small detent o, the end of which is wedge-shaped and the shank of
which projects through the case at o¹. By pressing on the milled head of the
shank the wheel c is raised and the connection between the roller band the
indices is broken. On releasing the milled head o¹ the spring of withdraws
the detent and allows the wheel c to drop again into gear with the screw b
When it is desirable to bring both the indices to the starting point the key p
formed at the end of the guide piece m is put on the end of the axle of the
pinions g and h, and by turning this key round in either direction the indices
are moved as required. During this operation it is desirable to raise the
wheel c out of gear with the screw b¹. The figures on the graduated dial aro
marked in both directions, so as to count the revolutions in whichever way the
shaft or other article may be revolving.
Having thus stated the nature of my Invention, and described a convenient
arrangement of machinery for carrying the same into operation, I wish to
observe that I do not limit myself to the details given, as the same may be
considerably varied or modified to suit the particular purpose for which the
instrument is required.
In witness whereof, I, the said John Benjamin Dancer, have hereto
set my hand and scal, this Twentieth day of August, One thousand
eight hundred and sixty-seven
J. B. DANCER. (L.S.)