IMPROVEMENTS IN STEAM ENGINE AND OTHER GOVERNORS
Year: 1854

page_text: LETTERS PATENT to Thomas Garnett, of Liverpool, in the County Palatino
of Lancaster, Engineer, for the Invention of "IMPROVEMENTS IN STEAM
ENGINE AND OTHER GOVERNORS."
Sealed the 2nd March 1855, and dated the 23rd September 1854.
PROVISIONAL SPECIFICATION left by the said Thomas Garnett at the
Office of the Commissioners of l'atents, with his Petition, on the
23rd September 1854.
I, THOMAS GARNETT, of Liverpool, in the County Palatine of Lancaster,
Engineer, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN STEAM ENGINE AND OTHER GOVERNORS" to be as follows:-
My Invention consists in the peculiar arrangement of a governor, which
I propose to call a parabolic motion regulator or revolving pendulum.
It is connected with, and when in motion revolves on or about, an upright
spindle, in such a manner that any solid or fluid body confined within certain
limits to the axis, by a centripetal agency, shall be constrained to rise or fall
during the increase or decrease of the centrifugal force in the arc of a
common parabola, the axis about which it revolves being the axis of the
parabolic arc.
My regulator is in form somewhat similar to the common "Watt's

page_text: governor; the height of the intersection of the line of direction of the cen-
tripetal force, with the axis of revolution above the plane of revolution of the
weights, is constant in the same regulator. To the vertical spindle I affix a
guard, accurately formed on the inside to a curve, so that the centres of
gravity of the weights employed, moving along it, will describe the arc of a
parabola; or instead of this arrangement I affix to or form on the vertical
spindle one or more evolute curves, so that a band or bands, or other con-
necting medium attached to the weights employed, shall, in their evolution
from the curve by the moving of the weights, cause their centres of gravity
to describe the arcs of a parabolic involute curve; by which arrangement
the weights will not so readily fall again as in the case of the common
governor, but remain in the last position at which they arrive until there is a
further alteration in the pressure of the steam or of the load.
The property of the parabola described is capable of various modifications
in its application to motion regulators, or for like objects, when bodies while
revolving about an axis are caused to move by variation of motion in the arc
of a parabola.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Garnett in the Great Seal Patent Office on the
20th March 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
GARNETT, of Liverpool, in the County Palatine of Lancaster, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-third day of September, in the year of our Lord
One thousand eight hundred and fifty-four, in the seventeenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Thomas Garnett, Her special licence that I, the said Thomas Garnett,
my executors, administrators, and assigns, or such others as I, the said Thomas
Garnett, my exccutors, 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, exercsie,
and vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN STEAM
ENGINE AND OTHER GOVERNORS," upon the condition (amongst others) that I,
the said Thomas Garnett, by an instrument in writing under my hand and

page_text: seal, 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 Thomas Garnett, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:-
My said Invention refers to the construction of centrifugal motion regu-
lators or governors, so arranged that the revolutions in any given case shall
be isochronal, notwithstanding any variation of the plane of revolution of the
revolving bodies, or of their distances from the axis.
And for the better understanding of my said improvements, in respect to
their nature and object, and for the more effectually carrying the same into
effect, I will now proceed to describe the several details thereof, reference
being had to the Drawings hereunto annexed, in which the same letters
apply to like warts throughout

page_text: embraced by two parallel rods J, J, which pass through a slot formed on the
spindle A, B, and upright pieces on the bush thereof.
11, H', (Figure 6,) pendulum rods, of a length equal to the mean radius of
curvature of the parabolic are, in which they would rise or fall if suspended by
bands II, II, Figure 4.
F, F, (Figure 7 and 8,) a fluid weight within a bowl C", D", E", formed
accurately on the inside, as shown in the section, so that its surface would
coincide with or be parallel to that formed by the revolution about its axis of a
parabolic arc whose half parameter is equal to the altitude due to the time of
revolution. K, a cistern in the centre of the bowl, having a flange on the
bottom formed to a curve parallel to the bowl, or nearly so, and fixed so as to
leave a small space for the fluid to pass underneath along the surface of the
bowl. F", the mercury placed therein, with a heavy float L, connected by a
swivel and chain or rod with a counterbalance, and thereby in
way to the valve or apparatus to be regulated.
any convenient
M, (Figures 1, 3, and 4,) a vertical compensating weighted lever or a
pulley, having a hanging weighted band or chain connected with the regulator
to act on the weights, adding to or subtracting from the force of gravity,
according as it may be adjusted.
I would here observe that the peculiar action of my parabolic regulator is
the same in the several forms shown, and may be explained by reference to the
Diagram, Figure 3; in which, N, V, represents the axis of revolution, and P
the mean centre of oscillation of one of the weights, and p, P, p', the parabolic
path in which it moves, by the increase or decrease of the centrifugal force.
P, O, the horizontal plane of revolution; N, O, the altitude duo to the time
of revolution. The centre of oscillation will vary a little, as indicated by the
dotted lines; and though, in many cases in practice, the consequent variation
of altitude will scarcely be appreciable, still it is very desirable to obtain as
constant an effective height or time of revolution as possible; and the com-
pensating weighted lever or pulley M effects this, or compensates for the
variation.
It will thus be seen that my improved governor is connected with and
when in motion revolves on or about an upright axis or spindle, in such a
manner, that any solid or fluid body confined within certain limits to the axis
by a centripetal agency, shall be constrained to rise or fall during the increase
or decrease of the centrifugal force in the arc of a common parabola, or in an
are whose radius of curvature at a given point shall coincide with the radius
of curvature of a common parabola at the same point. The time of revolution
or the height of intersection of the line of direction of the centripetal force,

page_text: with the axis of revolution above the plane of revolution of the revolving
body F, is constant in the same regulator, notwithstanding any variation of
the plane of revolution, or of the distance from the axis of the weight or
weights. Also, the line of direction of the centripetal force coincides with the
resultant of the centrifugal force and the force of gravity in any position of
the weight; and the equilibrium of the forces is only maintained in any
altered position of the weight by the same constant time of revolution, which
is the leading feature of my said Invention as regards its application to
centrifugal motion regulators.
The centripetal agency I employ is either a curved guard, (or guards, if more
than one,) fixed to the upright spindle (as shown in Figures 1 and 7), and so
accurately formed on the inside that the centres of gravity of the weights
moving along it will describe an arc coincident with or parallel to that of a
common parabola; or I sometimes employ bands or other suitable media,
one end of which is connected with the weights, and the other end attached
to the upper part of an evolute curve, (or curves, if more than one,) fixed or
formed on the upright spindle, and so accurately formed on the upper side,
that when the weight moves from the centre, causing the evolution of the
band from the curve, its centre of gravity will describe an arc coincident with
or parallel to the corresponding parabolic involute curve; or I sometimes
employ pendulum rods, as in Figure 6; or, as in the common governor, with
the compensating apparatus M, so as to effect isochronal revolutions, or a
constant effective height.
The curved involute guard C, D, E, must have its upper surface formed
accurately to an involute curve, whose radii of curvature coincide with the
radii of curvature of the common parabola p, P, p'; this surface is therefore
parallel to it, and I describo this parabola by making its semi-parameter equal
to the altitude due to the time of revolution required. The weights F, Figure 1,
are fitted with a loose sheave or roller in cach, the centre pin passing through
the centre of gravity, as indicated by the dotted lines.
By these several arrangements of my said improvements in governors the
weights will not fall again after having risen by an increase in the motion
of the machine when the mean velocity is attained, as happens with the
common governor, but will remain in the last position at which they arrive
until there is a further alteration of the moving force. The property of the
parabola herein described is capable of various modifications in its application
to motion regulators, or for like objects, when bodies while revolving about
an axis are caused to move by the variation of motion in the arc of a
parabola.

page_text: Having thus described the nature of my said Invention, and several modes
of carrying the same into effect, I desire it to be clearly understood that
I do not confine myself to the application of the same, to any particular
machinery, or to the precise forms and details herein-before described, so
long as the peculiar feature of my said Invention is maintained in effecting
the constant effective height or constant time of revolution due to that height.
And I do declare that what I claim as my improvements are, namely,-
First, the peculiar construction of centrifugal governors, in which solid or
fluid bodies are so arranged as regards the ascent and descent of the weights
by the variation of the centrifugal force, that they shall move in an arc or
arcs coincident with or parallel to the arc of a common parabola.
Second, the centripetal guards C, D, E, shown in Figures 1, 4, and 7.
Third, centrifugal governors with pendulum rods, having their centres
of suspension on the side of the axis, contrary to that of their respective
weights.
And, fourth, the weighted vertical lever or weighted pulley M in combina-
tion with centrifugal governors, compensating for any variable altitude above
the plane of revolution, for effecting isochronal revolutions, as described.
In witness whereof, I, the said Thomas Garnett, have hereunto set my
hand and seal, this Nineteenth day of March, in the year of our
Lord 1855.
THOMAS GARNETT. (Ls.)