A SPEED INDICATOR
Year: 1885

page_text: ] KILLINGWORTH WILLIAM HEDGES of 25 Queen Anne's Gate Westminster in:
the County of Middlesex, Civil Engineer do hereby declare the nature of my
Invention for "A SPEED INDICATOR "to be as follows:-
This invention relates to improvements in an instrument which consists of a
tube partly filled with water which, when rapidly rotated, indicates the speed by
the position of the bubble of air which is more and more depressed as the velocity
of the tube containing the fluid increases. My improvement is first in the
arrangement of the tube, which I make of glass, talc or metal, providing suitable
transparent sight holes if an opaque material is employed, this tube should be a
cylinder of exactly the same diameter all the way up and flat inside at the top
and mounted so that it can be rotated with case, When used as a portable
instrument it is necessary to quicken the descending action of the bubble.
I therefore provide small ribs on the inner circumference or on the top or
bottom of the tube which catch the water and cause it to rotate when the tube
itself is rotated.
To observe the position of the bubble I mount a stationary screen outside the
tube and cut out slots across which either fixed or movable rings may be placed.
and a true reading taken by getting two in line.
The height of the fluid in the tube may be regulated by a tap but the amount
of depression for any given speed may be adjusted by altering the air space or by
adding or taking away a false lining; either methods may be employed, without
changing the fluid, by providing a connection through a suitable stuffing box with
the outside of the tube.
To drive the apparatus I mount the tube on a frame so arranged that it shall
be supported at top and bottom and at the same time be free to rotate;-when
used as a portable indicator I prefer driving the tube by means of a flexible shaft
furnished at one end with a connection which may easily be adjusted to the end
or side of the shaft the speed of which it is required to ascertain.
The tube may be furnished with metallis ends and be made detachable from
the driving gear so that tubes of different diameters may be easily substituted.

page_text: I, KILLINGWORTH WILLIAM HEDGES, of 8 Quality Court, Chancery Lane,
London, W.C. do hereby declare the nature of my invention for "A SPEED
INDICATOR" and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:-
It has been proposed to measure velocity of rotation by ascertaining the height
to which liquid is raised at the circumference and depressed at the centre by
centrifugal force in a rotating vessel. The heights or depths due to different
velocities do not follow the proportions of those velocities, and therefore with such
instruments it is not easy, without specially graduated scales to determine the
velocity due to a given height or depth. Now, according to my invention, instead
of allowing the liquid to rise to various heights at the periphery of the vessel,
I limit the height to which it can rise by putting on the partially filled vessel a
cover which is flat over all that part of its surface which the liquid can touch.
In that case, the depth to which the middle of the liquid becomes depressed is
directly proportional to the velocity of rotation. I can therefore by inspection of an
equally divided scale, ascertain at once the speed of rotation corresponding to
an observed depression of the middle of the liquid.
Fig. 1 of the accompanying drawings is a side view partly in section of an
instrument according to my invention. A glass tube or cylinder A is mounted
so as to revolve freely on a vertical axis being driven by bevil gear B, or otherwise,
at a speed which has a known ratio to the speed of the rotating shaft whose
velocity is to be indicated. I enclose the tube A, which is covered by a flat top,
within a stationary tubular casing C, having slits through its opposite sides so
that by looking through them the depression of the liquid at its middle can be
seen. A ring D is fitted to slide along the casing C which is graduated by equal
divisions. While the tube A and the liquid in it revolve, the ring D is slid to
such a position that its nearer and its farther edges are brought into coincidence
with the vertex of the central parabolic depression of the liquid. The observer
can then read on the scale of the casing, the speed of rotation.
The quantity of liquid in the tube has in the first place to be adjusted to the
graduations of the scale, but the level which the liquid should havo when at rest
being once determined, it is only necessary afterwards to raise or reduce the liquid
to that level before taking an observation of speed.
Instead of using the sliding ring D; wires W may be fixed across the opening of
the casing as shewn in Fig. 2, each wire marking the place of the liquid depression
corresponding to a certain velocity.
The tube A may be driven as shewn in the side view Fig. 3 and plan looking
from below Fig. 4, by a pin P entering a cross-cut, this connection admitting of
the tube being readily removed and replaced.

page_text: Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
A speed indicator consisting of a glass tube partly filled with liquid and caused
to revolve on a vertical axis, the tube having at the top a flat cover to arrest the
liquid, substantially as herein described.
.ABEL & IMRAY,
Agents for the Applicant,
28, Southampton Buildings,
London, W.C..