AN IMPROVED METHOD OR METHODS OF WEIGHING, AND CERTAIN IMPROVEMENTS IN WEIGHING MACHINES
Year: 1840

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
HENRY BURSILL, of River Lane, Lower Road, Islington, in the County of
Middlesex, Gentleman, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by
Her Letters Patent under the Great Seal of Great Britain, bearing date at
Westminster, the Twenty-eighth day of May, in the third year of Her reign,
did, for Herself, Her heirs and successors, give and grant' unto me, the said
George Henry Bursill, my exors, adñors, and assigns, Her especial license,
full power, sole privilege and authority, that I, the said George Henry Bursill,
my exors, admors, and assigns, and such others as I, the said George Henry
Bursill, my exors, adññors, and assigns, should at any time agree with, and no
others, from time to time and at all times hereafter during the term of
therein expressed, should and lawfully might make, use, exercise
and vend, within that part of the United Kingdom of Great Britain and
Ireland called England, Her Dominion of Wales, Town of Berwick-upon-
Tweed, and in all Her Majesty's 'Colonies and Plantations abroad, my
Invention of "AN IMPROVED METHOD OR METHODS OF WEIGHING, AND CERTAIN
IMPROVEMENTS IN WEIGHING MACHINES;" in which said Letters Patent is con-
tained a proviso that I, the said George Henry Bursill, shall cause a particular
description of the nature of my said Invention, and the manner in which the
same is to be performed, to be inrolled in Her Majesty's High Court of
Chancery within six calendar. months next and immediately after the date of
years

page_text: the said in part recited Letters Patent, as in and by the same, reference being
thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
George Henry Bursill, do hereby declare that the nature of my said Invention,
and the manner in which the same is to be performed, are fully set forth in the
following description thereof, reference being had to the Drawings hereunto
annexed, and to the figures and letters marked thereon, that is to say:-
My said improved method or methods of weighing, and my said improve-
ments in weighing machines, (under which terms of weighing and weighing
machines I comprehend all methods of ascertaining and all machines or
instruments for ascertaining the weight or pressure of substances, whether in
a solid, or fluid, or an aeriform state,) are exemplified in the seven different
forms of weighing machines or parts of machines, represented in the said
Drawings hereunto annexed, and herein-after more particularly described.
Number 1 (Figures 1 and 2) represents a machine for weighing solids
and fluids. Figure 1 is an elevation, and Figure 2 a longitudinal section of
this machine. A is a cylindrical vessel which fits into a socket B affixed to
the stand C; and F, another vessel of like form but smaller dimensions, which
has at bottom an open communication by means of the tube G, G, with A.
These two vessels are filled with mercury up to the same level in both; they
may be made of any suitable material, but that which I find to answer best is
well-baked pipe clay, to which mercury has less tendency to adhere than any
other substance I have tried. D is a piston which rises and falls freely in the
mercurial holder A, and may be of any suitable material; if made of pipe clay
it should be strengthened by means of a stiff wire passed through the centre of
it; E is a scale pan affixed to the top part of the piston D, on which the
article to be weighed is placed; H is a glass tube which is fitted air-tight into
the-upper end of the smaller mercurial holder F, and may be either left open
at top to the atmosphere or closed by a cork or stopper. - Into this tube some
fluid of less specific gravity than mercury, (as water, or oil, or spirit, or any
dilute acid;) and which should have a strong distinguishing colour given to it,
as red or green, is poured until it fills the space in the holder F left unoccupied
by the mercury, and reaches a little way up the said tube H; J, J, is a move-
able index plate properly graduated and placed alongside the tube H, the zero
point (0) of this scale being brought to an exact level with the top of the
coloured fluid in the tube H. It will be obvious from these arrangements that
in placing a weight on the scale pan E, it will press down the piston D, which,
displacing a quantity of the mercury in the holder A proportional to its bulk,
will cause that in the holder F to rise, and the displaced water or other fluid of

page_text: less specific gravity resting upon it to ascend in the tube H. It will be obvious,
also, that the rise of the colored fluid in the tube H will be greater than the
excess of the vertical rise of the mercury in the holder A beyond the vertical
rise of the mercury in the holder F, exactly in the proportion in which the
colored fluid is of less specific gravity than the mercury. When water is
employed with mercury there is a range of about one foot in the tube (H)
for every inch in the mercurial holder A. In order that the piston D may
maintain its perpendicularity, it is connected with a parallel motion K, K;
working on separate centres; a counterpoise of equal weight with the scale pan
and piston is attached to one or other of the rods K, K, but it is not seen in
the Drawing; instead of one column of a fluid of less specific gravity than
mercury, two or more columns of the united length of the one, each having
a separate holder like F may be connected with the mercurial holder A, but.
at different levels, and by these means an equally long indication may be
obtained at a height more convenient to the eye.
Number 2 (Figures 3 and 4) represents another machine by which heavy
as well as very light weights may be ascertained with equal facility and
exactness, and with the aid comparatively of a very small quantity of mercury.
A is a tube for holding the mercury, which, instead of being vertical, as usual,
is of the form of an arc of a circle, and is made of the same material as before
recommended for such mercurial holders. Near its lower extremity this tube
has an open communication with a vertical glass tube containing colored
water or any other fluid of less specific gravity than mercury. D is a piston
which moves up and down freely in the mercurial tube A, and is affixed by
means of a nut and screw to a scale beam C overhead.. B is a knife edge.
which serves for the fulcrum of the scale beam C, and the length of curve
given to the mercurial holder A will, of course, depend on the distance at
which it is placed from the fulcrum B. P and P³ are two scale pans
suspended from the beam C, one for heavy weights and the other for light;
that for heavy weights being suspended on the well-known steelyard principle,
nearest to the fulcrum B, and that for light weights the farthest from it.
The distance between these pans may be so proportioned that they shall
indicate any definite proportional differences which may be desired; as, for
example, they may be so placed in relation to each other that the one shall
indicate pounds and ounces and the other ounces and drachms, while one index
plate will serve for both. When the positions of the scale pans have been..
determined, trial is to be made of the effects produced, by various weights
placed in them on the fluid in the indicator tube. H, and the adjustable
index plate is to be graduated accordingly.

page_text: Number 3 (Figures 5, 6, 7, and 8) represents a machine on the same
principle as that last before described, with some slight modifications. Figure 5
is an elevation of the machine, and Figure 6 a sectional view. The beam
rests on knife edges, and to prevent it from swerving to either side, which
would be prejudicial to the precision of its action, the knife edges are filed off
at each end to a fine point, to which a moveable steel bush is nicely adjusted
by means of a screw, as shown in Figure 7. Another mode of effecting the same
object is represented in Figure 8, in which the parts next adjoining to the
knife edges are made somewhat conical, so that they shall not slip out of
their places. A machine of this description is well adapted for heavy
weights.
Number 4 (Figures 9 and 10, elevation and section,) represents a machine
on the same principle as the two preceding machines, but with two adjustable
index plates, placed apart from each other, so that the weights indicated by the
machine may be seen at the same instant by two different parties, as, for
example, buyer and seller, or employer and servant. A is the scale beam, and
B a rod or arm working on a separate centre so as to maintain the perpen-
dicularity of the piston C.
Number 5 (Figures 11 and 12, clevation and section,) is a machine with
curved mercurial holder, the operations of which are indicated by the fall;
instead of the rise, of the fluid in the indicator tubes. The top of the working
piston in the mercurial holder carries a beam resting on knife edges, to one
end of which scale pans are attached, any weight placed in either of which
raises the piston more or less out of the mercurial holder, and thereby
causes the mercury to fall, and with the mercury the fluid in the other
indicator tube. As the range of this machine can be prolonged almost
indefinitely, by simply prolonging the beam at the weighing end, and
which can be done without. any inconvenience by making that end of
different lengths hinged together and. folding back one upon the other, after
the manner of a foot rule, or by making it of a number of-concentric pieces
like a telescope (care being always taken to provide, at the opposite end of the
beam, an exact counterpoise for any additional weight thrown by such
prolongation upon the weighing end), this machine will be found capable of
determining with the utmost. exactness the very smallest differences of weight,
while, in consequence of every difference of altitude in the mercury being many
times magnified in the second indicator tube, the observer can be at no
difficulty at any time in assigning to these differences their true numerical
value..
Number 6 (Figure 13) represents a self-acting contrivance, which may be

page_text: added to any of the machines before described, for the purpose of compensating
at all times for the effects of changes of temperature on the indicator columns;
or either of them, whenever it is considered of sufficient importance to do so,
and which contrivance is also applicable to other machines on the common
construction, barometers especially, in which only a column of mercury is made
use of. A is a vertical rod of zinc or other material, readily expansible bý
heat, which is firmly fixed at bottom to the framework of the apparatus, and
carries at top an arm D, the short or socket end of which a turns on a fixed
centre b. The long end c of the arm d is at first made of any indefinite length,
and afterwards shortened to a certain required length, in manner following:
I first ascertain by experiment the highest point to which the indicator columns
or the mercurial column only, where there is no other indicator column made
use of, will be raised by the greatest degree of temperature to which they are
likely or it is likely to be ordinarily subjected. I then expose the zinc rod' A'
and its arm D to the same degree of heat, and find by repeated trials a point
in the long end c of the arm D, which always corresponds exactly with 'the
elevation of the indicator columns or column; I then cut off the long end of
the arm close to the point thus formed, and secure each point by a pin or
screw on which it may turn freely to a sliding index placed previously,
graduated as usual into inches and parts of inches. I next attach to the
index plate a little lower down a projecting' stay of the same length
as the arm D after it has been so shortened, having a ring or hole in it
through which the zinc rod A may rise and fall freely, by which means the
parallelism of the rod and index plate may, under all circumstances, be
sufficiently preserved. Now, as the zinc rod A will always contract and
expand simultaneously with any contraction or expansion of the mercurial-
or other column, aud in a certain determinate ratio thereto, it follows that
the figures on the index plate, after having been once correctly adjusted;
must always indicate the true weight or pressure, whatever the change of
temperature may be. When the compensation apparatus I have just described
is applied to cistern barometers, the lower end of the rod A must be on a level
with the mercury in the cistern C, shown by the dotted lines in the Drawing
Number 6, and which cistern C is so constructed that the level of the mercury
within it will be always the same, so long as the barometer is kept in an
upright position, notwithstanding any of the ordinary. changes in the atmo-
spheric pressure to which it may be subjected, or any rise or fall that may take
place in the vertical mercurial column. If the tube containing the vertical
mercurial column is of large bore, a tube of proportionally smaller bore may

page_text: be used for the cistern or réservoir, and when much length of cistern is
required, it will be found of great convenience to give it a spiral form.
for use:
Number 7 (Figure 14) represents another contrivance for effecting the same
"object as that accomplished by Number 6. A parallel motion P carrying an
arrow pointer C is attached to a sliding index plate A, which parallel motion
is connected with a toothed quadrant and pinion in such manner that as the
index plate rises or falls the arrow pointer C shall always move in à contrary
'direction, up or down. The zero point of the index plate is then brought
by hand to a level with the mercury in the short leg of the mercurial tube B,
by which operation the arrow pointer C of the parallel motion is simultaneously
raised or lowered to a level with the top of the mercury in the long arm of the
tube, when at a given standard temperature (say fifty-five degree, or temperate)
and at a given standard pressure (say twenty-nine inches and a half) so as to
balance the atmospheric column. The instrument is now supposed to be set
When afterwards it is desired to know what correction is to be made
in the indications of the barometrical scale for any increase or diminution
in the volume of the mercurial column owing to increase or diminution of
temperature, all that is necessary, after adjusting the zero to the level of the
mercury in the short arm, is to look at the arrow pointer C, and if there is any
portion of mercury above that point (as shewn in the figure) it indicates an
encrease in the whole volume of mercury employed and a proportionate
encrease in the volume of the barometrical column, while if the level of the
mercury is below the pointer C, the empty space between will indicate a
corresponding decrease. I do not confine myself to the use of a parallel motion,
such as shewn in the Drawing, since the same results can be obtained by a cog
and racks, and other well-known contrivances. In the case of marine
barometers I make the short arm of the syphon tube of an equal bore with
that part of the long arm usually called the indication part, but I connect the
short arm with the indication part by means of a tube of capillary bore....
And having now described the nature of my said improved methods and
machines, and the manner in which the same are to be performed, I declare
that what I claim as-new-and of my invention is, the employment for weighing.
purposes of two indicator columns, one of mercury and the other of some fluid
of less specific gravity than mercury, in conjunction with all or any of the four
additions following:-First, a piston or plunger, by the descent or rise of which
in.the mercurial column the weight or pressure of the substances weighed is
ascertained; second, with parallel guide rods to preserve the perpendicularity of
the piston or plunger, and so diminish friction; third, with a self-acting

page_text: apparatus to compensate for the effects of changes of temperature in the
indicator columns or column, and fourth, with an adjustable index plate. I
claim also the employment for weighing purposes of a mercurial column or
columns in conjunction with a piston or plunger and parallel guide rods; I
claim also the employment of tubes or vessels of the form of an arc of a
circle for containing the mercury, whether two indicator columns are used or
only one, and with or without pistons and guide rods, the steelyard principle
and a compensation apparatus, or any of them; I claim further the employ-
ment of a scale beam on the ordinary steelyard principle, with two indicator
columns or with one column only, consisting of mercury, and with or without
the addition of parallel guide rods, and a compensating apparatus, or either of
them, and whether the said beam works on knife edges or not; and lastly,
I claim the application of the said compensation apparatus, according to either
of the forms thereof represented in Numbers 6 and 7 (Figures 13 and 14),
not only to weighing machines constructed according to any of my said
improved methods, but to weighing machines on any of the ordinary plans of
construction (barometers especially). And I declare, that though I have
exemplified the said improved methods by the machines and parts of machines
represented in the Drawings hereunto annexed, I claim an exclusive right for
the period expressed in my said herein-before in part recited Letters Patent, to
make, use, exercise, and vend all weighing machines (understanding by that
term all machines employed for ascertaining the weight or pressure of substances,
whether in a solid, fluid, or an aeriform state,) which shall be on the like principle
or principles in whole or in part, and not differ in any material respect there-
from; and such my Invention being to the best of my knowledge and belief,
entirely new and never before used within that part of Her Majesty's United
Kingdom of Great Britain and Ireland, Her Dominion of Wales, Town of
Berwick-upon-Tweed, or in any of Her said Majesty's Colonies & Plantations
abroad, I do hereby declare this to be my Specification of the same, and that
I do verily believe this my said Specification doth comply in all respects fully,
and without reserve or disguise, with the proviso in the said herein-before in
part recited Letters Patent contained; wherefore I hereby claim to maintain
exclusive right and privilege to my said Invention.
In witness whereof, I, the said George Henry Bursill, have hereunto set
my hand and seal, this Twenty-seventh day of November, in the year
of our Lord One thousand eight hundred and forty.
GEORGE HENRY (L.s.) BURSILL.

page_text: AND BE IT REMEMBERED, that on the Twenty-seventh day of November,
in the year of our Lord 1840, the aforesaid George Henry Bursill came before
our said Lady the Queen in Her Chancery, and acknowledged the Specification
aforesaid,-and-all and every thing therein contained and specified; in the form
above written. And also the Specification' aforesaid was stamped according
to the tenor of the Statute made for that purpose.
Inrolled: tho Twenty-eighth-day of November, in the year of our Lord
One thousand eight hundred and forty.