IMPROVE- MENTS IN VENTILATING APPARATUS, AND IN MOTIVE-POWER ENGINES FOR PROVISIONAL SPECIFICATION
Year: 1875

page_text: LETTERS PATENT to William Cunningham, of Dundee, in the County
of Forfar, North Britain, Engineer, for the Invention of "IMPROVE-
MENTS IN VENTILATING APPARATUS, AND IN MOTIVE-POWER ENGINES FOR
PROVISIONAL SPECIFICATION left by the said William Cunningham
at the Office of the Commissioners of Patents, with his Petition,
on the 19th October 1875.
I, WILLIAM CUNNINGHAM, of Dundee, in the County of Forfar, North
3 Britain, Engineer, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN VENTILATING APPARATUS, AND IN MOTIVE-POWER ENGINES
FOR WORKING THE SAME, AND APPLICABLE OTHERWISE," to be as follows, that is
to say:
:-
This Invention has principally for its object the ventilation of large
buildings or spaces of any kind in a simple, positive, easily regulated,
and efficient manner, and with small power, and it consists mainly in

page_text: the employment of a large pump of simple and light construction, and
having a piston moving so slowly as to exert no more pressure on the
air than that barely sufficient for its displacement, such piston also
having a long stroke derived in a simple and convenient manner without
intermediate continuously revolving gearing from the comparatively
short stroke of a small motive-power engine worked by water or other
Al
intermediate continuously revolving gearing from the comparatively
short stroke of a small motive-power engine worked by water or other
fluid.
In one modification of the improved apparatus the air pump is a long
horizontal chamber of rectangular cross section constructed of wood or
any other suitable material, and the piston is a light frame stiffened by
diagonal bracings and covered with any convenient fabric or sheet,
whilst it is fitted to slide on horizontal guides fixed along the sides of
the chamber. Inlet and outlet valves are fitted at both ends of the pump
chamber, the outlet valves leading into a passage or passages com-
municating with the outside of the building, whilst the inlet valves
communicate with the inside, or vice versa. These valves consist of
light flaps of leather or other suitable material closing against gratings
presenting an aggregate area which is by preference at least equal to
that of the piston. The piston is moved backwards and forwards by
ropes passing round guide pulleys at the ends, and thence both pro-
ceeding to a large pulley or drum mounted on a shaft, which has fast on
it pinion in gear with a rack formed on or attached to the piston rod of
a small hydraulic cylinder. As the piston of the hydraulic cylinder
reciprocates it makes the pulley or drum rotate to a limited extent in
alternate directions, and thence through the ropes the necessary move-
ment is imparted to the air piston. The hydraulic cylinder is fitted with
a valve or valves worked by means of a tumbler, or in any other con-
venient way, but in order to prevent sudden jerks at the ends of the
strokes the openings in the cylinder ends for the ingress and egress of
the water are made or placed relatively to the stroke of the piston, so
that as it approaches either end the piston gradually covers nearly the
whole of the openings, and thus gradually checks the passage of the
water, then on the return stroke the water is compelled to enter the
cylinder very slowly at first because of parts only of the openings being
uncovered, and thus all jerk or concussion is avoided at the change of
stroke. To prevent the piston from being pressed laterally or unequally
when partly covering the openings, two or more of such openings are
made so as to balance each other round each end of the cylinder.

page_text: This improvement is advantageously applicable to any motive-power
engine having a reciprocating piston unconnected with a continuously
revolving shaft.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Cunningham in the Great Seal Patent
Office on the 18th April 1876.
°
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
CUNNINGHAM, of Dundee, in the County of Forfar, North Britain,
Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Nineteenth day of October, in the year
of our Lord One thousand eight hundred and seventy-five, in the
thirty-ninth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said William Cunningham, Her
special licence that I, the said William Cunningham, my executors,
administrators, and assigns, or such others as I, the said William
Cunningham, my executors, 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, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "IMPROVEMENTS IN VENTILATING APPARATUS, AND IN MOTIVE-
POWER ENGINES FOR WORKING THE SAME, AND APPLICABLE OTHERWISE," upon the
condition (amongst others) that I, the said William Cunningham, my
executors or administrators, by an instrument in writing under my,
or their, or one of their hands and seals, 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 William Cunningham, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in

page_text: and by the following statement in writing, reference being had to the
accompanying Drawings, that is to say :-
My said Invention has principally for its object the ventilation of large
buildings or more or less enclosed spaces of any kind in a simple,
positive, easily regulated, and efficient manner, and with small power,
and it consists mainly in the employment of a large pump of simple and
light construction, and having a piston moving so slowly as to exert no
more pressure on the air than that barely sufficient for its displacement,
such piston also having a comparatively long stroke derived in a simple
and convenient manner without intermediate continuously revolving
gearing, from the short stroke of a small motive-power engine worked
by water or other fluid.
The improvement in the motive-power engine is mainly intended to
be used when the motive fluid is water or other liquid, and is designed
to prevent sudden jerks at the ends of the strokes. In carrying it out
the internal openings in the cylinder ends for the ingress and egress of
the water are made or placed relatively to the stroke of the piston so
that as it approaches either end the piston gradually covers nearly the
whole of the openings, and thus gradually checks the passage of the
water. Similarly on the return stroke the water is compelled to enter
the cylinder very slowly at first because of parts only of the openings
being uncovered, and thus all jerk or concussion is avoided at the chango
of stroke.
And in order that my said Invention, and the manner of performing
the same may be properly understood, I hereunto append three Sheets
of explanatory Drawings to be herein-after referred to, and repre-
senting modifications of my improved apparatus. In these Drawings the
same reference numerals are used to mark the same or like parts
wherever they are repeated.
Figure 1, on Sheet 1 of the Drawings, is a plan of one modification
of the apparatus, and Figures 2 and 3 are side and end elevations. The
air pump is in this example a long horizontal chamber 1 of rectangular
cross section constructed of wood or any other suitable material, and the
piston 2 (indicated by dotted lines) is a light frame stiffened by diagonal
bracings, and covered with any convenient fabric or sheet, whilst it is
fitted with horizontal side bars to slide on horizontal guides 3 fixed
along the sides of the chamber 1. Inlet valves 4 and outlet valves 5

page_text: are fitted at both ends of the pump chamber 1, the outlet valves, which
are indicated by dotted lines, leading into a passage 6 constructed along
one side of the pump chamber 1, and communicating by a flue 7 with
the outside of the building, whilst the inlet valves communicate with
the inside of it; or the inlet valves into the pump chamber may have
the air entering them from the outside of the building to be propelled
by the pump through the outlet valves into the building. The inlet and
outlet valves 4, 5, consist of light flaps of leather or other suitable material
closing against gratings presenting an aggregate area, which is by pre-
ference at least equal to that of the piston 2. The piston 2 is moved
backwards and forwards by light ropes, cords, or bands 8 passing round
guide pulleys 9 at the ends of the pump chamber 1, and thence both
proceeding to a pulley 10 mounted on a shaft which has fast on it a
pinion 11 in gear with a rack 12 formed on or attached to the piston
rod 13 of a small hydraulic cylinder 14. This cylinder and parts con-
nected with it are shown enlarged in Figure 4. As the piston of the
cylinder 14 reciprocates it makes the pulley or drum 10 rotate to a
limited extent in alternate directions, and thence through the ropes 8,
which are fixed to the pulley, the necessary movement is imparted to the
air piston 2. When the stroke of the air piston 2 is not excessive, say
when it is not over ten feet, I prefer to have the pulley 10 of a size to
make about revolutions, in which case neither of the ropes 8 will
ever make more than one turn round the pulley, but in any cases in
which it may appear to be more convenient the pulley 10 may be made
comparatively smaller with the ropes, cords, or bands
more than once round, and suitable grooves or other devices being used
to prevent the different convolutions from interfering with each other.
When thin bands are used the second convolution of each may without
inconvenience be wound upon the first. The rack 12 and the stroke of
the piston attached to it should in all cases be long enough to correspond
with the entire stroke of the air piston 2.
passing each
The details of the hydraulic engine are herein-after described with
reference to Sheet 3 of the accompanying Drawings.
A second modification of my improved apparatus is shown on Sheet 2
of the accompanying Drawings, Figure 5 being a plan, Figure 6 a hori-
zontal section of one half of the apparatus, and Figures 7 and S side
and end elevations of it. In this modification two rectangular pump
chambers 1a, 16, are constructed vertically side by side, and the air

page_text: pistons 2a, 2b, indicated by dotted lines are arranged to move vertically.
The air pistons are driven both by one hydraulic engine and pulley 10
placed so that the rope 8 from one side of the pulley passes directly
down to one air piston 2 a, whilst that from the other side passes first
over a guide pulley 15, and thence down to the other air piston 26. The
air pistons 2a, 2b, have also by preference a rope 16 attached to their
under sides, and proceding from one to the other round guide pulleys 17
at the bottom of the apparatus. The bottom connecting rope 16 might
however be dispensed with in some cases.
With the view of keeping the air pistons 2 a, 2b, horizontal and stiff,
light metal tubes are fixed through their centres, and the ropes 8, 16,
pass through these tubes, or may be fixed to their ends; or the ropes
may be attached to sets of cords branching to the corners of the pistons.
With such arrangements the air pistons will require no guiding beyond
that of the pump chambers 1 a, 1 b, up and down which they move, and
which they fit as closely as they conveniently can without hindering
their free movement.
The inlet and outlet valves and passages may be arranged in various
ways, but in the arrangement shown on Sheet 2 of the Drawings the
pump chambers 1 a, 16, are placed with one half on one side of a longi-
tudinal vertical partition 18, and the other half on the other side of that
partition. The inlet valves 4 are all placed at one side of the partition 18
and the outlet valves 5 at the other side, there being inlet and outlet
valves at both top and bottom of both pump chambers 1a, 16, as will
be easily understood from the Drawing. The inlet valve side or the
outlet valve side of the partition 18 may be put in communication with
the interior of the building or space to be ventilated, accordingly as it is
in each case considered desirable to draw the air out of or force it into
such space, the other side being in each case made to communicate with
the external atmosphere.
Figures 9 and 10 on Sheet 3 of the accompanying Drawings are
horizontal and vertical sections of my improved hydraulic engine, and
which is shown in side elevation in Figure 4, Sheet 1 (also drawn to a
small scale in other Figures). The cylinder 14 is made with an ordinary
port face, on which there works a slide valve 19 moved by a bar attached
to two pistons 20, 21. These pistons 20, 21, work in cylindrical recesses
in the ends of the valve chamber, and passages 23, 24, (indicated by

page_text: dotted lines in Figure 4) lead to the recesses from a four-way cock 25,
which has in connection with it two other passages, one a branch from
the main inlet 26 and the other a branch to the main outlet 27. The
slide valve 19 is shifted by the water, accordingly as the cock 25 directs
the water to act on either piston 20, 21, and the cock 25 has fast on its
plug a lever 28, which is adjustably connected by a link 29 to an arm 30
fixed to the rack 12 and piston rod 13, so that on the main piston
reaching either end of its stroke the cock 25 is so far turned as to admit
water to the proper end for shifting the slide valve 19 for the return
stroke.
The herein-beforo described apparatus for shifting the slide valve I
do not claim as new excepting as combined with my improvement
relating to the internal openings of the cylinder passages. The main
piston 31 (indicated by dotted lines in Figure 10) is made of such a
length, and has such a stroke, as to partly cover the passage openings 32
when it approaches either end of the cylinder. The openings 32 are formed
with narrow grooves 33 extending from them to the ends of the cylinder,
and when the piston in approaching either end covers the main parts 32
of the openings its motion is not suddenly stopped, but is gradually
diminished, the water getting away from between the piston and the
cylinder end or cover by the narrow grooves 33. In a similar way when
the piston begins its return stroke the water is compelled to enter the
cylinder very slowly at first by the grooves 33, and cannot exert its full
force until the main parts 32 of the openings are uncovered, and thus all
jerk or concussion is avoided at the change of stroke. To prevent the
piston 31 from being pressed laterally or unequally when covering the
main parts 32 of the openings the cylinder passages are made with two
branches 34, each passing a quarter round the cylinder, and with two
diametrically opposite openings into the interior of the cylinder. There
might be three or more openings (32) placed so as to balance each other,
or each passage might communicate with a channel formed entirely
round the interior of the cylinder, and in this last case a number
of fine grooves 33 may be made from each channel to the end of the
cylinder 14.
This improvement is advantageously applicable to any motive-power
engine having a reciprocating piston unconnected with a continuously
revolving shaft; it is, however, best suited for cases in which water or
other liquid is employed and the speed is not required to vary very much,

page_text: as the grooves 33 should be larger for quick speeds and smaller for slow
ones.
Having thus particularly described my said Invention, and the
manner of performing the same, I have to state that I do not restrict
myself to the precise details herein described or delineated, but that
what I believe to be novel and original and claim as the Invention
secured to me by the herein-before in part recited Letters Patent is,―
1. The arranging or combining together of the parts of ventilating
apparatus substantially in the improved manner herein-before described,
a large pump being employed of simple and light construction with a
slowly moving piston having a comparatively long stroke derived without
intermediate continuously revolving gearing from the short stroke of a
small motive-power engine.
2. The moving of the pistons of ventilating pumps by means of ropes,
cords, or bands passing round guide pulleys and attached to a pulley or
drum which is made to rotate alternately in opposite directions by a
reciprocating motive-power engine.
3. The forming of the openings (32, 33,) in the inner ends of the
cylinder passages of reciprocating motive-power engines, in the manner
and for the purpose herein-before described.
In witness whereof, I, the said William Cunningham, have here-
unto set my hand and seal, this Fifteenth day of April, in the
year of our Lord One thousand eight hundred and seventy-six.