A METHOD OR METHODS FOR RAISING AND LOWERING THE WATER IN CANAL LOCKS
Year: 1818

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
BOGAERTS, of Air Street, Piccadilly, in the County of Middlesex, Gentleman,
send greeting.
WHEREAS His most Excellent Majesty King George the Third did, by
His Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland, bearing date at Westminster, the Tenth day of November,
in the fifty-ninth year of His reign, give and grant unto me, the said John
Bogaerts, my exors, admors, and assigns, His especial licence, full power, sole
privilege and authority, that I, the said John Bogaerts, my exors, admors,
and assigns, during the term of years therein mentioned, should and lawfully
might make, use, exercise, and vend, within England, Wales, and the Town
of Berwick-upon-Tweed, and also in all His Majesty's Colonies and Plantations
abroad, the Invention communicated to me by John Groetaers, now residing
in Brussels, of "A METHOD OR METHODS FOR RAISING AND LOWERING THE WATER
IN CANAL LOCKS;" in which said Letters Patent there is contained a proviso,
that if I, the said John Bogaerts, shall not particularly describe and ascertain
the nature of the said Invention, and in what manner the same is to be
performed, by an instrument in writing under my hand and seal, and cause
the same to be inrolled in His Majesty's High Court of Chancery within
six calendar months next and immediately after the date of the said Letters
Patent, that then the said Letters Patent, and all liberties and advantages
whatsoever thereby granted, shall utterly cease, determine, and become void,

page_text: as in and by the same, relation being thereunto had, will more fully and at
large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
John Bogaerts, do hereby declare that the said Invention, or the said method
or methods, for raising and lowering the water in canal locks, and the
manner in which the same are to be performed, are fully described and
ascertained in the following Specification thereof, reference at the same time
being had to the annexed Drawings, that is to say:
The nature of the said Invention will be partly understood by those who
are conversant with the subject of canal locks, when I say that it may be
considered a double plunger lock, but as the nature of the peculiar method or
methods of applying a plunger or plungers, for the purposes herein-before
stated, will be clearly developed in the description of the manner in which it
is to be performed, I will therefore proceed to describe the same said method
or methods as follows (that is to say):
Figure 1 and 3 are vertical sections of the apparatus hereby intended to
be described, and the said sections are in the direction of the length of the said
apparatus. The lines A B, B C, C D, D E, and E A, represents the figure
or shape of a cistern or vessel for holding water, which said cistern or vessel I
shall call the plunger cistern; the lines B, C, and C, D, form the bottom;
and A, B, and D, E, the end of the said cistern. The said ends are circular,
and are both described from the centre C. To the undér side of the said
cistern are attached two vessels of a triangular shape, namely. B, C, F,
and C, G, D; these vessels are intended to make up a certain bulk; or
to occupy a certain space, and although the principle of this Invention
does not exclusively require that the said space or bulk should be filled
by hollow vessels (for if the same bulk were to be made up of any solid
material it would theoretically answer the purpose equally well), yet in
practice it will be found expedient to make them, and I do make them
hollow water-tight vessels, and which, for the sake of distinction, I shall
call air vessels; I shall also, for the same reason, call the aforesaid
cistern A, B, C, D, E, together with the said air vessels attached or appended
thereto, as before described, the double plunger (or, for the sake of brevity,
the plunger). I will here remark, that in the several Figures or Diagrams
in the annexed Drawings, I have, as far as I have found it practicable, made
use of the same letters or figures of reference to denote the same things.
In Figures 1 and 3, a, C, b, represent a triangular shaped fulcrum or prop,
for the plunger to rest upon, and inasmuch as the angle F, C, G, formed by
or between the two air vessels, is greater than the angle of the fulcrum a, C, 6,

page_text: it will allow the plunger, when placed upon the upper edge of the fulcrum, to
swing or move backwards or forwards through an angular space equal to the
difference between the angle F, C, G, and a, C, b.
Figure 4 is a plan or bird's-eye view of the plunger and apparatus, which I
shall more particularly explain as follows, that is to say:-A, B, C, D, is the
plunger; N, O, P, Q, are the walls surrounding or enclosing the plunger..
The dotted lines a, b, c, d, describe the situation of the base; and the dotted
line C, C, the upper edge of the said fulcrum; each end of the fulcrum is made
to project beyond each side of the plunger, and both the said ends are made
to enter into the side wall O and Q, so as to form a junction therewith; H
and I represent two canal locks, one on each side of the plunger; and e, f, g,
and h, represent the lock gates; J is a wall on the outer side of the lock
I; and. K is another wall on the outside of lock H. As the locks and the lock
gates which I employ in conjunction with the plunger do not differ in any
essential point, either in their construction or in the manner of using them,
from canal locks and gates in common use (excepting in the method or
methods for raising and lowering the water in the said locks), and as the
relative situation of the said locks with each other, and with the plunger, is
sufficiently plain from the Drawings, I need not be more particular in the
description thereof. It is evident from the Drawings that the walls N, O, P,
and Q, in Fig. 4, which surround or enclose the plunger form a rectangular
basin or cistern of a similar shape to that of the plunger, and that the fulcrum
as shewn in Fig. 1, 2, and 3, and by the dotted lines in Fig. 4, forms a par-
tition across the middle of the same, so that the said rectangular basin or
cistern, by means of the said fulcrum, is divided, and, in fact, becomes two
basins or cisterns, which I shall, in the following part of my Specification, call
receivers. In Fig. 1 and 3, i, j, a, C, and k, l; b, C, represent those receivers ;
and in Fig. 4, the said receivers are shewn at m, i, j, n, and m, k, l, n.
Between one of the locks and one of the receivers I make a passage of com-
munication, and in like manner a similar communication in made between the
other lock and the other receiver. The aforesaid passages of communication
are made by leaving an opening in the walls between and at the bottom of
each of the said locks and the receivers respectively; and as it is desirable>
that the said passages of communication should be as large as they can conve
niently be made, in order that the same water may pass through them with
little resistance, I make the said passages nearly of the whole length between '
each of the end walls N and P, and the fulcrum, so that the length of one of
the said passages would be nearly equal to the distance between 6 and I, or
between a and j, in Fig. 1 and 3; and I make the height of the said passages'

page_text: The
of communication such as that the top or upper side of the said passages shall
not be at any time higher than the water in the lower level of the canal.
I would here observe, that it is not essentially necessary that there should be
any covering to the said passages, nor that there should be any wall between
either of the locks and the receivers with which they are intended respectively
to communicate; but if such covering and such walls were omitted, then the
cubical contents of each lock must in effect be increased, and consequently the
plunger must be made larger, for as it is the object of this Invention that each
end of the plunger should displace as much water from the receiver into which
it is made to descend as will raise the water in the contiguous lock to a given
height, or, in other words, fill the said lock, it is evident that the dimensions
of the plunger must be such as will produce that effect. It being obviously
desirable that the contents of the lock or locks, and consequently the dimen-
sions of the plunger, should be the least possible, therefore I do cover the said
passages of communication, and introduce walls, as before described.
situation of the said passages of communication is shewn in Figure 1 and 3, at
b, t, p, o, and at j, a, r, q. Immediately above and upon the plunger I take
one or more troughs or vessels; but in Figure 1, 2, 3, and 4, only one is
shewn. In Figure 1 and 3, s, t, u, v, is a section, and in Figure 4, s, t, u, v, is
a plan or bird's-eye view of the said trough or vessel, which I shall herein-after
denominate the compensator; the middle of this vessel; with regard to its
length, I place directly above the axis of the plunger, and in the lateral
direction nearly midway between the sides of the plunger, as shewn in
Figure 4. The sides of the said compensator may or may not be hollowed
out, as shewn in Figures 1, 2, and 3. As the only objects to be attained in
doing so are the weight and quantity of material are lessened, and it gives a
lighter appearance to the compensator. As the ultimate object to be attained
by the Invention is the passing of boats or other vessels from a bigher to a
lower level, or contrarywise, upon canals, without the loss or expenditure of
water, I will proceed to describe the application of the said Invention to that
purpose, as follows, that is to say:-The dotted line over which upper level
is written in Figure 1 represents the height of the water in the upper level
of the canal, and the dotted line over which lower level is written represents
the height of the water in the lower level of the said canal. The upper
and lower levels are also similarly distinguished on the plan, Figure 4. I
will now suppose, by way of hypothesis, the plunger to be placed or to stand in
the position as represented in Figure I, and suppose that the end A, B, F, C,
completely fills the receiver. It is evident, that if any water had previously
occupied the said receiver, the said water would have been by the descent of

page_text: that end of the plunger displaced, and forced or driven through the passage of
communication into one of the locks to which the passage leads, namely, into
the lock I, and I will suppose the quantity of water so driven out to have
been sufficient to fill the said lock. I will also suppose a like quantity of
water to occupy the other receiver, and that the water in the said other
receiver, namely, c, b, l, k, in Figure 1, and the water in the lock H, and also
the water in the lower level of the canal, stand at or have one common level.
Under these circumstances the lock I would be full, and ready to admit a
boat from the upper level of the canal, and the lock H would be empty, and
ready to admit a boat from the lower level of the said canal. I will suppose
that a boat has been admitted into each lock, one through the upper gates at h
of the lock I, and the other through the lower gates e of the lock H, and the
said gates again to be shut or closed. If then the position of the plunger be
changed, the water in the receiver c, b, l, k, would be forced out and made to
fill the lock H; and on the contrary the end A, B, F, C, of the plunger would
be raised or withdrawn from the receiver-i, c, a, j, and permit the water to
return back into the said receiver from the lock I. The plunger would now
stand in the position shewn in Figure 3. The boat in the lock I would have
descended from the higher to the lower level, and the boat in the lock H
would have ascended from the lower to the higher level.
In the foregoing description of the plunger and the compensator I have
mentioned them merely as cisterns or vessels without water; but as it is
obvious, from the nature of the operation to be performed by the plunger, that an
adequate force or weight must be applied to one end of the plunger, in order to
force the same downwards to procure the displacement of the water from one of
the receivers, and thereby to fill one of the locks, it becomes necessary for me
to describe the manner in which I procure the said requisite weight, which is as
follows, that is to say:-Taking the plunger in the position shewn in Figure 1, it
will be there seen that one half of the bottom of the plunger vessel, 'namely,
B, C, is considerably inclined from the line i, c, the said line i, c, being level, and
that the other half of the said bottom, namely, C, D, lies horizontally or level.
Into the said plunger vessel or cistern A, B, C, D, E, I introduce a quantity
of water sufficient to fill it to a certain height, as described in Figure 1 by the
line 17 and 18, above the central part at C, and also above that part of the
bottom of the plunger cistern represented by C, D, whatever depth of water
there may be above C, D. It is clear that a stratum of water of the same
depth will be spread over and occupy the whole area of the said plunger
cistern, and as the said stratum of water lies equally over both ends of the said
plunger cistern, it can have no effect in adding more weight to the one end

page_text: thereof than to the other; but it will be evident that the space below the level
line i, c, is also filled with water, and whatever the quantity may be (that it
will operate as a weight to counteract the buoyancy of that end of the plunger,
which in this position is immersed in the water contained in the receiver i, C, a, j.
It is here necessary for me to state that the edge of the fulcrum at C should
be level, and that it should be of the same heighth as the water in the upper
level of the canal, or nearly so; a prefer placing it a little above the said height,
in order to prevent the water escaping over the said edge from the one receiver
to the other. I would here also state, that I leave a sufficient space between
the sides of the plunger and the walls inclosing the said plunger, so as to allow
the plunger to move freely without touching the said walls. From what has
been said it will appear that when one of the locks is full of water, and (as
in Figure 1) one end of the plunger is down, the water will fill the space
between the sides of the plunger and the walls up to the level of the line i, C,
consequently, that part of the end of the plunger which is below the line
2, C, will be the measure of the weight necessary to sink it, or to counteract the
hydrostatic pressure which will oppose its descent. But it will be found that
the weight of the water in that end of the plunger would be insufficient to
produce that quantity of displacement, or to sink the said end to the depth
required, I therefore employ the compensator, into which 1 introduce as much
water as by experiment I find will have the effect of sinking the end of the
plunger. In Fig. 1, t, s, w, represents the quantity of water in the compen-
sator, which, from the position of the said vessel, occupies one end thereof, and
consequently operates as so much weight to sink that end of the plunger. If
now the angular position of the plunger, that is, if the end D, E, be depressed,
and consequently the end A, B, thereof be raised, then the water in the lock I
would flow back into the receiver i, c, a, j, and the said lock-would be gra-
dually emptied; and on the contrary, the water in the other receiver C, b, l, h,
would, by the descent of the other end of the plunger, be displaced, and
gradually fill the lock H. Also, in moving the plunger from the said position,
the end D, E, being depressed, the water in the plunger would have a
natural tendency to run towards that end as the said end was progressively
forced downwards. For this reason the end A, B, would become lighter as
it rose, and the end D, E, heavier as it descended; the water in the com-
pensator would also make a corresponding movement from the end which
was rising towards the opposite or descending end. Fig. 2 shews the
plunger and compensator in a horizontal position, in which position the
water in both would be distributed in equal quantities over each end.
Fig. 3 shews the same apparatus in a contrary position to that exhibited

page_text: in Fig. 1. I have said above, that the water in the plunger should stand at a
certain depth above the central part C, which central part may be considered
the axis, round which the plunger turns, and I have done so for the following
reason, namely, that as all the water in the plunger which is actually employed
as a weight to sink either of the ends thereof, or to counteract the buoyancy of
the said ends as one or the other is progressively depressed or sunk, it is
desirable that the transfer of the said water from one end of the plunger to the
other should be effected with as little external force as may be. But that this
may be better understood, I will suppose that the quantity of water in the
plunger is no more than sufficient to fill the end A, B, C, in Fig. 1, up to the
dotted line i, C, or that the water therein stands level with the said axis, but
not above it; now, if the end A, B, of the plunger be raised, the water con-
tained in it would also be raised, and begin to flow over the central part or
axis at C into the other end, and the quantity of water so flowing over in any
given time would depend upon the quantity of the external force employed to
change the position of the plunger, and as the water will only continue to flow
over the axis so long as it is higher on one side of the said axis than on the
other side thereof, it is clear that the external force employed to turn the
plunger upon its axis must be equal to maintaining the aforesaid difference of
level, or, in other words, it must be equal to raising a stratum of water of some
given depth above the axis, and the said stratum would be equal in area to
half the horizontal area of the plunger, or to the area of one end thereof, and
as a small external force, when applied to move the plunger, would raise only
a thin stratum of water, the section of the water which was thereby made to
flow over the axis would necessarily be of a corresponding and inconsiderable
depth, and the transfer of the water from one end of the plunger to the other
would occupy a much longer time than if the depth or section of the water
over the axis had been greater, admitting that the same external force had
been employed to move the plunger in both cases; for, according to the well-
known principles of hydraulics, if the depth or section of the water over the
axis C be made greater, a greater quantity of water will run over in the same
time with the same difference of level, and consequently with the same external
force applied to move the plunger.
I will now more particularly describe the use of the compensator, and
explain the reasons why it becomes necessary to employ a certain quantity
of water in it. I have herein-before said, generally, that the weight of the
water in one end of the plunger, as before described, namely, in A, B, C,
would be found insufficient to force down the said end, or to overcome
the buoyancy thereof, without the aid of an additional weight of water in

page_text: the compensator; one reason is as follows, namely, that in constructing the
plunger, materials of some kind must be employed, and according to the
nature of those materials, they will be more or less bulky. Now, as the quan-
tity of water which is displaced from the receiver by the plunger, or by one end
thereof, will be measured by the external demensions of such part of the
plunger as may be immersed in the said water, and as also the quantity of
water which may at the same time be contained in the inside of the plunger
will be measured by the internal demensions of the said plunger, it is evident
that the latter or internal demensions must always be less than the former or
external demensions; consequently the quantity of water which can be intro-
duced into the plunger must, in all cases, be less than the quantity required,
and the deficiency will be less or more, according to the bulk of the materials of
which the plunger is composed. If a double-plunger lock is made, agreeably
to the modification herein-before described, there is another reason for intro-
ducing an additional weight of water into the compensator, which is as follows,
namely, by examining the figure or shape of the plunger, the relative situation
of the water occupying the space i, C, B, and that of the air vessel B, C, F,
and by considering the circumstances to which the whole are exposed, it will
be found that a further additional quantity of weight will be required to
counteract the buoyancy of the end A, B, of the plunger. It is evident that
the water contained in the space i, C, B, would displace a quantity of water
from the receiver equal to its own bulk. But the air vessel will have also
displaced as much water from the receiver as is equal to its bulk; and inas-
much as the weight of the air vessel will be found to be less than an equal
bulk of water, it is also evident that the difference between the weight of
the materials of which the said air vessel was made, and the weight of the
water which the said air vessel displaces, would be the measure of the buoyancy
of the said air vessel. It will also appear, from the situation of the other or
elevated end of the plunger in Fig. 1, that a part of the air vessel C, D, G,
at G, remains immersed in the water; consequently, as the buoyancy of the
said immersed part will operate to buoy up the end E, D, of the plunger, and
to depress the opposite end A, B; therefore, if the buoyancy of the said air
vessel at G be deducted from that of the air vessel C, B, F, the remainder or
difference will be a given quantity, for which a compensation is required, and
which may be supplied by putting more water into the compensator.
Having, as above, explained the use of the compensator, and the reasons why
the said compensator is necessary, a competent engineer will be at no loss in
applying them properly under circumstances which may require the relative di-
mensions of the apparatus to be different to those described in this Specification.

page_text: With regard to the air vessels, I have said that in theory it would
answer the purpose equally well if the spaces which the said air vessels occupy
were to be filled with solid materials; but if the said spaces were to be so
filled with solid materials, they would add much more weight to the plunger,
consequently would require the said plunger to be made stronger and at more
expence. I therefore prefer and do employ air vessels as above described.
In the above description, I have, in order to avoid confusion, given no directions
for determining the dimensions of the said plunger and other apparatus. I
shall now, therefore, explain the same in the following manner, that is to say:-
In every case the dimensions of the canal lock or locks to which the said
plunger is intended to be applied will determine the dimensions of the said
plunger, and also of the receiver or receivers; for it is evident, from the nature
of the operation, that the quantity of water contained in either of the receivers
(previously to the descent of one end of the plunger into such receiver) must
be equal to the quantity required to fill the lock and also to fill the spaces
between the walls and the plunger. To avoid being misunderstood, I would
here observe that by one of the dimensions of the lock, namely, the depth
thereof, I mean the difference between the upper and lower level of the canal.
In Fig. 1, the end E, D, of the plunger is represented in its state of greatest
elevation; now, I mean that the quantity of water contained in the receiver, as
shewn at b, x, y, l, must be equal to the cubical contents of the lock and the
spaces between the walls and the said plunger. It will be apparent (to every
person competent to undertake the erection of such an apparatus), from the
foregoing description of this Invention, that the lateral dimensions and the
depth of the said receiver or receivers, and consequently of the plunger, may
be infinitely varied, so as to comply with the aforesaid conditions, (viz), as to
the quantity of water to be contained in the said receiver or receivers below
the line X, Y, in Fig. 1, the said line being always upon a level with the
water in the lower level of the canal. It will render this part of the subject
sufficiently intelligible if I give an example, which I shall herein-after do by
describing more particularly and practically the construction of the aforesaid
double plunger and other apparatus, together with the dimensions of the same,
that is to say-Figures 1, 2, 3, 4, and 5 exhibit different views of the
aforesaid double-plunger lock. The dimensions of the canal locks H and I, as
shewn in the plan, Figure 4, are as follows, namely, 86 feet long, 14 feet 6 inches
wide, and 8 feet deep. The dimensions of the plunger, air vessels, compen-
sator, the receivers, and the fulcrum are as follows, namely, the whole length
of the plunger, from outside to outside, is 80 feet, the width thereof 46 feet,
and the said plunger is twenty feet deep at each end in the inside, and the

page_text: depth over the central part at C is 11 feet 6 inches. The dimensions of the
air vessels are as follows, namely, the side B, C, (which is also the bottom of
one end of the plunger vessel,) is 40 feet long, the side or bottom B, F, is
31 feet long, and the side or end F, C, 17 feet, and the width of the said air
vessels (for they are both of the same dimensions) is the same as that of the
plunger, namely, 46 feet; the dimensions of the compensator are 92 feet in
length, 11 feet in depth at the end thereof, and 21 feet in width. As the
internal dimensions and shape or figure of the receivers are determined from
the outside dimensions and figure of the ends of the plunger, I need not specify
them more particularly than to observe that between the sides of the said
plunger and the walls or sides of the receiver I leave a space of about six
inches. The heighth of the fulcrum, from the base of the upper edge thereof
at C, is about 16 feet 6 inches, and the breadth of the base about 11 fcet. The
scale accompanying the annexed Drawing, or exhibited thereon, having the
word scale written over it, is a scale of feet, by which the dimensions of any
particular part of the said apparatus delineated thereon may with a sufficient
degree of accuracy be ascertained, allowance at the same time being made for
any deviation from the truth by using so small a scale, the said Drawings
having been made from a scale of one-sixteenth of an inch to a foot. I hereby
also declare, that I do make the said plunger vessel, air vessels, compensator,
and fulcrum, of iron, wood, or other like material.
And in order to explain more particularly the manner of constructing the
said plunger, together with the said air vessels, I will further describe the same,
as follows, that is to say-Figure 5 is a sectional view of the said plunger,
which is here represented as being made of wood, and by which is exhibited
the manner in which I make the framework, in order to strengthen the said
plunger and render it capable of sustaining the weight of water with which it
is loaded. The construction of the said framework being sufficiently explained
by the Drawing, it is only necessary for me to say that there are three distinct
pieces of framework therein shewn, namely, one in the upper part of the
plunger, standing upon the bottom thereof, or upon the upper sides of the air
vessels, and the two other pieces of framework are shewn in the inside of the
air vessels, namely, one in each. Between the under side of the upper piece of
the framework and the upper sides of the two other pieces, as shewn in the
air vessels, the planks which the said air vessels are covered are interposed,
and the three pieces of framework are made to stand in the same plane, and
are firmly fixed to each other by screwed bolts; similar pieces of framework
are repeated five times in the width of the plunger, that is, one set at each of
the sides thereof, and three others so placed as to divide the width of the

page_text: plunger into four equal parts. In the plan, Fig. 4, the dotted lines 1, 2, and
3, 4, and 5, 6, and 7, 8, and 9 and 10, shew the situations in which the said
pieces of framework are placed. At the central part C, Fig. 5, I employ a
cast-iron or other metal plate or plates (the figure of which is there represented,
and coloured black), by which I connect the angle pieces of the air vessels,
and, consequently, the air vessels themselves to each other; and on the under
side of the said plate or plates there is a hollow groove, which is made to fit
and rest upon the rounded edge of the fulcrum. The said pieces of frame-
work I also strengthen with wrought-iron straps or braces. The said straps
or braces (which are also coloured black) are fastened to the top of the middle
post (such as is usually called a king post) at 11, and the said straps or bolts
are also fastened to the several parts at the bottom of the plunger, as marked
12, 13, and 14, where they are securely fastened to the framework. In order
to strengthen the lower angle of the air vessel and the lower angle of the
plunger vessel, I introduce knee pieces, which I generally make of iron; these
knee pieces are shewn at 15 and 16. The fulcrum is here represented as
being made of cast iron, but it may be made partly of brickwork or masonry
and partly of iron; and the said fulcrum ought to stand upon a firm foundation,
so as that it may not give way under the weight of the plunger and its contents.
The outsides of the air vessels and plunger vessels are made water-tight by
covering them with wooden planks, in a similar manner to the planking of a
ship; and I make the thickness of the said planks from 2 to 3 inches. It will
be found on examining the principles upon which this plunger is constructed,
as herein-before described, that when a proper quantity of water is introduced
into the vessel of compentation and plunger vessel, and when the plunger is
nicely balanced upon its axis, the power or force requisite to move the said
plunger will be little more than that which will overcome the friction and the
inertia of the water which is to be put into motion. The operation of changing
the position of the plunger will be performed in a longer or shorter time, as
the external force applied thereto is smaller or greater. Motion may very
conveniently be given to the plunger by. fastening a rope or chain to each end
thereof, in such a manner that either end of the said plunger may be drawn
down by a sufficient number of men, or the said rope may be passed through
such a number of pulleys or be applied upon a roller or cylinder, or, according
to any of the well-known means of increasing the mechanical effect to be
produced, it may be put into motion and the change of position effected by the
power of one man.
Fig. 6 is also a plan of the double punger and the two locks, as above
described, but it is drawn to a much smaller scale, and only intended to shew

page_text: that the canal on each side of the said plunger, &c., must be made of such a
width as will permit the boats or other vessels navigating the said canal to
pass freely from the said canal into the said lock. Although I have herein-
before described two canal locks in conjunction with the plunger, and although
it might in some cases be expedient to construct two locks, in order to give
facility and dispatch in passing a great number of boats, yet, as in many other
cases where a smaller number of boats was required to be passed in the same
time, one of the said locks would be found sufficient for that purpose. In the
last-mentioned case a saving of expence will result from the substitution of a
basin or side pond in lieu of one of the said locks, and connecting it with one
of the receivers by a passage of communication in the same manner as another
lock would have been connected, and the area and depth of the said basin or
side pond must be made the same as the area and depth of the said other lock
would have been made.
I shall now describe one other modification of the arrangement of this
Invention, which, perhaps, not being obvious at first view as a mere difference
of the application of the principle, I describe in manner following, that is to
say: Instead of placing the plunger between two canal locks in the manner
herein-before described, and instead of allowing the boats, barges, or other
vessels to ascend or descend from one level of the canal to another by one
operation or one change of position of the plunger, I construct two locks in
a line with each other, in such a manner that one pair of gates or one gate
(as in narrow canals, where only one gate is used) may be placed between the
two locks, and thereby the boats or other vessels may be permitted to pass
from one of the said locks to the other, by which means I am enabled to
construct the said two locks so as only to require three pairs of gates; for
the middle gates or gate serves in common for both locks, and both the said
locks are placed in the same line with the canal; and I place the receivers, with
the plunger, &c., on one side of the same two locks, which said two locks I shall
distinguish by the upper and lower lock; for the upper lock communicates with
the upper level of the canal, and the lower lock with the lower level; and I
also make passages of communication between each of the locks and each of
the receivers, in a similar manner to those herein-before described, so as that
by depressing one end of the plunger the water may be raised in one of the
locks and lowered in the other, and vise versa, and I so place the receivers
and plunger, with relation to the aforesaid two locks, that the middle of the
plunger shall be nearly opposite to the middle gates or gate thereof, or, in other
words, that the fulcrum upon which the plunger is suspended shall stand
opposite to the said middle gates, and that the said fulcrum shall be placed

page_text: nearly at right angles with the lines or sides of the said locks; I shall also,
for the sake of distinction, call one of the receivers the upper and the other
the lower receiver, because they respectively communicate with the upper and
lower locks; and assuming any height or fall between the upper and lower
levels of the canal, the said height or fall is, by the intervention of the afore-
said two locks, divided into two equal parts, or nearly so, and a boat or other
vessel may be passed from one level to the other by two operations of the
plunger instead of one, as herein-before described; but in order more clearly to
shew how this is effected, I shall further state that the bottom of the upper
lock is higher than that of the lower lock by one half of the whole height or
fall between the upper and lower level of the canal, and that the bottom of the
upper receiver is also higher than that of the lower receiver, and as the lower
receiver is consequently deeper than the upper one, it necessarily requires that
the air vessel applied in the lower receiver should be made, and I therefore
do make it deeper than the air vessel in the upper receiver.
With regard to the plunger cistern, no change in its construction from that
herein-before described is required, excepting such change as will in all cases"
be required in its linear and angular dimensions, so as to adapt it to the fall or
descent from one level of the canal to another, and to the different sized locks to
which it may be applied. The application of this last-mentioned modification
will be still better understood by describing the operation of passing a boat
through the two locks. I shall therefore suppose a boat coming down the
canal, and ready to enter the upper lock, the water in the said lock having
been previously raised in the said upper lock by depressing the upper end of the
plunger; the boat is admitted into the said upper lock, and the gates having
been closed, the contrary end of the plunger is then depressed, the water in
the upper lock descends (and with it the boat), and the water in the lower lock
is made to ascend until the water in both locks becomes of the same level:
The middle gates are then opened and the boat is passed in the lower lock.
The middle gates being again shut, the upper end of the plunger is depressed,
by which the water in the upper lock is raised to the height of the upper level
of the canal, and the water in the lower lock in lowered to the lower level
of the canal, and the boat is thus, at two operations of the plunger, passed in
either direction from one level of the canal to the other. And I hereby
declare that altho' I have in this Specification or description made mention of
canal locks, lock gates, cisterns, receivers, plungers, air vessels, and other
apparatus, in order to explain the nature and use of the said Invention, all of
which are in their individual or separate characters old inventions, I do not
claim any exclusive privilege or monopoly in the making, using, or vending the

page_text: same separately. But I will now proceed to shew in what the said Invention
more particularly consists, as follows, namely,-
First, by making the bottom of the aforesaid plunger cistern A, B, C, D, E,
as in Fig. 1, in such a manner that the two parts of the said bottom, viz, B, C,
and C, D, may make an angle with each other, as is there represented, or in
such a manner that the said two parts B, C, and C, D, may be considered as
lying in two planes intersecting each other at C, or as intersecting each other
in the horizontal line n, m, in the plan, Fig. 1, and by suspending or supporting
the said cistern by or upon a fulcrum or axis, so that the angular position of
the said cistern may be changed, and that if a quantity of water, such as I have
herein-before described, be put into the said plunger cistern, the said water
may be made to flow from one side or end of the said cistern to the other, over
the central part at C, whenever one or other of the ends of the said cistern
became depressed, or whenever the angular position of the said cistern became
changed.
And, secondly, in applying the aforesaid compensator to the aforesaid plunger
cistern, and supplying the same with water, for the purposes herein-before
mentioned. I must here, however, observe, that as this Invention is applicable
to the raising and lowering the water in canal locks, and can only be made
applicable thereto when employed in conjunction with the said locks and
receivers, and when the said locks and receivers are properly supplied with
water; I hereby declare that I claim the privileges granted to me by His
Majesty's Letters Patent aforesaid, for the disclosure of my said Invention,
only when employed for the aforesaid purposes.
I, lastly, declare that the principal or essential part of this Invention consists
in so constructing one vessel or cistern, namely, the aforesaid plunger cistern,
as to answer the purpose of two plungers, and so applying water therein, and
also in so applying water in the vessel or vessels of compensation so as that
in whatever position the aforesaid plunger may be placed, the said plunger may
be in a state of equilibrium, or nearly so, but it must be understood that such
an effect can only take place when the receivers and canal locks are properly
supplied with water, and employed in conjunction with the said plunger, as
herein-before described.
In witness whereof, I, the said John Bogaerts, have hereunto set my
hand and seal, this Tenth day of May, in the year of our Lord One
thousand eight hundred and nineteen.
JOHN (L.S.) BOGAERTS.

page_text: AND BE IT REMEMBERED, that on the Tenth day of May, in the year
of our Lord 1819, the aforesaid John Bogaerts came before our said Lord
the King in His Chancery, and acknowledged the Specification aforesaid,
and all and every thing therein contained and specified, in form above written.
And also the Specification aforesaid was stamped according to the tenor of
the Statute made for that purpose.
Inrolled the Tenth day of May, in the year of our Lord One thousand
eight hundred and nineteen.