AN IMPROVED SPEED INDICATOR
Year: 1876

page_text: LETTERS PATENT to John Butler, of Grosvernor Street, and James Butler, of
Sevastopol Street, in Belfast, Ireland, for the Invention of "AN IMPROVED
SPEED INDICATOR."
Sealed the 1st September 1876, and dated the 10th March 1876.
PROVISIONAL SPECIFICATION left by the said John Butler and James
Butler at the Office of the Commissioners of Patents on the 10th March 1876.
JOHN BUTLER, of Grosvenor Street, and JAMES BUTLER, of Sevastopol Street, in
Belfast, Ireland. "AN IMPROVED SPEED INDICATOR."
This Invention relates to a novel contrivance for indicating the speed in revo-
lutions per minute, or other required form of observation of engines and shafting,
the object being to ensure a steady action of the index needle or pointer which
cannot be attained in apparatus constructed on the principle of the pendulum
governor.
L
The improved “speed indicator" consists of an open vessel containing mercury or
other suitable fluid, and which is fixed to the top of a vertical spindle to which
rotary motion is given from the mechanism whose speed it is desired to observe.
In this vessel, which may be either circular or polygonal, or furnished internally
with radial vanes or webs, is fitted a central vessel communicating therewith by
sinall opening at or near the bottom. These vessels are supplied with mercury or
equivalent fluid, and when at rest the mercury will be at the same level in both
vessels. Within the inner vessel or compartment is placed a float or piston resting
upon the surface of the mercury or other fluid. This float is connected by suitable
mechanism to an index pointer, mounted in front of a graduated dial. The position
of the pointer on the dial will show the variations in speed; the pointer following
the rise or fall of the float as the speed of rotation of the vessel containing the
mercury is increased, the mercury is caused to flow from the inner to the outer
compartment of the vessel and thereby sink, the float resting on the mercury. In
like manner as the speed decreases the reverse action will take place and the float
will again rise, thereby causing the index pointer to mark a diminished speed.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said John Butler and James Butler in the Great Seal Patent Office on the
9th September 1876.
JOHN BUTLER, of Grosvenor Street, and JAMES BUTLER, of Sevastopol Street'
in Belfast, Ireland. 'AN IMPROVED SPEED INDICATOR."
"
The object of this Invention is to construct an instrument for indicating the
speed in revolutions per minute of engines, shafting, &c., in such a manner that the
index needle or pointer will not oscillate as is commonly the case in those instru-
ments wherein the motion is got from a modification of the pendulum governor, but
will receive when moved a steady progressive notion. The means whereby this
object is attained will be understood from the following description and accom-
panying Drawing, wherein the same letters of reference apply to the same or like
parts in all views.
Fig. 1 is a vertical section of the instrument showing the connections of the
various parts; Fig. 2 is an elevation of the instrument "half-size" as used for
land or stationary engines; Figures 3, 5, 6, and 7 are detached views of various
parts of the instrument; Fig. 4 is a vertical section of the instrument as designed
for marine engines, the dial and rotating vessel for the float being carried on
gimbals.
a is a vessel containing mercury or other suitable fluid b. This vessel a is fixed to
the top of a vertical spindle c, which is carried by the main stand or framing d, and
receives its rotary motion from the mechanism, the speed of which it is required to
observe by means of a pair of bevel wheels e, and the shaft f¹ and bell pulley f
The vessel a may be either circular and plain inside, or be furnished with radial
webs, as shewn in sectional plan in Fig. 3, or be polygonal or canted with or without
radial webs, as shewn in sectional plan in Fig. 7. This vessel a rotates on its
vertical axis, and is divided into two chambers or compartments by a ring a¹, one
chamber being inside the ring a¹, and the outer or annular chamber being formed
by the ring a¹ and the outer vessel a. These two chambers or compartments are
connected by an opening or openings a² in the bottom edge of the ring a¹, so that
when the mechanism is at rest the mercury b or other suitable fluid is at the same
level in both chambers. Inside the ring a', which forms an open cylinder, is a hollow
float or piston g resting upon the surface of the mercury bor other fluid, and
connected by the rods g¹, levers g, and rack and pinion g³, and suitable mechanism
to the index finger or pointer ½ or graduated scale on the dial. By thus
connecting the pointer or finger h with the float g the variations in speed will be
shewn on the dial by the pointer h, the same being actuated by the rise and fall
of the float g. When the mechanism is at rest the float g is at its highest level, but
when motion is given to the instrument then as the speed is increased the mercury
b is thrown by centrifugal force on to the inner sides of the rotating vessel a, and
so the surface of the mercury b inside the ring a¹ is lowered, and a corresponding
movement is given to the float g and thence to the pointer on the graduated scale h¹.
As the speed increases the float g falls, but as the speed is lessened the float will
rise. It will be understood that the movement of the pointer his gradual and
steady, for owing to the mercury b being divided into two parts by the ring a¹ it
does not surge but passes gradually from one chamber to the other.
For marine purposes the form of instrument shewn in Figures 4, 5, and 6 will
be used, as it is necessary for the correct working of the instrument that the
vessel a containing the mercury b should rotate on a vertical axis. To accomplish
this the dial h¹ and its connections, as well as the rotating vessel a and its bearing
and cover d and propelling spindle c, are carried by gimbals i from the main stand
or frame, the rotary motion being communicated to the vertical spindle c from
the belt pulley f and shaft f¹ by means of universal and sliding joints as shewn,
which allow of the stand k or frame oscillating in any direction without affecting
the verticality of the spindle c.

page_text: "
Having now described the nature of our Invention of an 'Improved Speed
Indicator," and explained the manner of carrying the same into effect, we wish it to
be understood that under the above in part recited Letters Patent we claim,-
The arrangement of apparatus above described, whereby the flow of mercury or
equivalent fluid contained in a rotating vessel is caused to act upon an indicator in
the manner and for the purpose above set forth.
In witness whereof, we, the said John Butler, and James Butler, have hereunto
set our hands and seals, the Fourth day of September, in the year of our
Lord One thousand eight hundred and seventy-six.
fחזורו
D
JOHN BUTLER. (S.)
JAMES BUTLER. (LS.)