IMPROVEMENTS IN OBTAINING AND APPLYING MOTIVE POWER
Year: 1854

page_text: LETTERS PATENT to John Chillcott Purnelle, of Tachbrook Street, Pimlico,
in the County of Middlesex, for the Invention of "IMPROVEMENTS IN
OBTAINING AND APPLYING MOTIVE POWER."
Sealed the 23rd January 1855, and dated the 26th July 1854.
PROVISIONAL SPECIFICATION left by the said John Chillcott Purnelle
at the Office of the Commissioners of Patents, with his Petition, on the
26th July 1854.
I, JOHN CHILLCOTT PURNELLE, of Tachbrook Street, Pimlico, in the County
of Middlesex, do hereby declare the nature of the said Invention for "IM-
PROVEMENTS IN OBTAINING AND APPLYING MOTIVE POWER" to be as follows: —
These improvements relate to a new and improved arrangement of mechanism
or apparatus designed for the purpose of obtaining motive power in two ways;
first, by compressing atmospheric air in suitable vessels, and then employing
the elastic force thereof for exerting pressure alternately upon the upper and
under side of a piston, working air-tight in a cylinder closed at top and bottom,
and fitted with valves acted upon by a tappet motion for opening and closing
said valves when the piston is either at the top or bottom of the said cylinder;
secondly, in admitting atmospheric air in its natural state into a cylinder, fitted
with a piston and valves, as before stated, and in adapting two air pumps to
such said cylinder, for the purpose of exhausting the air and forming a partial
vacuum alternately above and below the piston, according as such said piston

page_text: is either at the top or bottom of the cylinder. The nature of this Invention
will, however, be better understood by the following description of the means
by which it may be carried into effect:_
And, first, as regards the construction of the apparatus or mechanism
which I employ for compressing atmospheric air, and for applying it as a
motive power, it is as follows:-I employ for the purposes of this Invention
a cylinder and piston, similarly constructed to those used in steam engines,
but with the steam, or rather, air way; made as short as possible, and opening
direct into the cylinder at top and bottom thereof. In connection with
these air passages is an air chest, which is connected by short pipes to a
pair of large cylinders, which I call condensers, same being open: at top and
fitted air-tight with pistons, and these condensers I put in connection with
one or two air pumps, by means of pipes fitted with valves, so as to shut
off at any moment either condenser. In operating with the above-mentioned
apparatus, the air is first pumped into one of the condensers by manual labour,
and when the condenser is sufficiently charged, according to the pressure
required, the pump (if only one is 'used) is then connected to a cranked shaft
attached to the apparatus, and fitted at one end with a fly wheel, and at the
opposite end with a crank, to which is attached the piston rod of the working
cylinder; and I make the apparatus self-acting by placing a heavy weight
upon the top of that condenser which has been charged with atmospheric
air; I then form a connection between the other and empty condenser and
the air pump, and admit the compressed air from the first condenser into the
working cylinder, by which motion is imparted to the air pump; and as the
second condenser is thus being filled with atmospheric air, the first condenser
is being discharged of compressed air; and when this last-mentioned condenser
is nearly exhausted, I then weight the piston of the other condenser, by which
the weight will be taken off the first condenser. I then put the empty con-
denser into communication with the air pump, and again fill this condenser
with atmospheric air, and weight the piston as before stated, and in this manner
and by these means I render the apparatus self-acting, or nearly so.
"..
And, secondly, as regards the construction of the apparatus or mechanism
which I employ for obtaining motive power, by exhausting a cylinder of the air
which it contains, it is as follows: I employ a working cylinder closed at top
and bottom, and fitted with a piston, as before stated with reference to the first
apparatus. To the top and bottom of this cylinder I connect air pumps, and
operate therewith in the following manner :-I exhaust the air from that part
of the cylinder which, for example, is above the piston, and simultaneously I
open a valve at the bottom of the cylinder, for the purpose of admitting

page_text: atmospheric air thereinto, and thus impart motion to the piston by reason of
there being a partial vacuum above the piston; and when the piston has reached
the end of its stroke a self-acting tappet movement reverses the position of
the valves, by opening the upper valve and closing the lower one, by which the
pressure of the atmospheric air will be exerted upon the upper side of the
piston, and the air exhausted from beneath it, and in this manner and by these
means reciprocating motion will be imparted to the piston of the working
cylinder and parts in connection therewith, and may be transmitted from thence
by spur gearing or other suitable means, and employed as a motive power in
any convenient manner. And, I would here remark that I am aware of motive
power having heretofore been obtained both by compressing atmospheric air in
a vessel and by exhausting it therefrom; but I am not aware of mechanism
or apparatus, similar to that above mentioned, having been employed to effect
the same, and it is this peculiar arrangement of mechanism or apparatus that
constitutes this Invention; the peculiar feature of novelty consisting in alter-
nately establishing and destroying a vacuum both above and below a piston
in a cylinder, for the purpose of obtaining direct reciprocating motion of the
said piston.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Chillcott Purnelle in the Great Seal Patent Office on
the 26th January 1855.
TO ALL TO WHOM THESE PRESENTS. SHALL COME, I, JOHN
CHILLCOTT PURNELLE, of Tachbrook Street, Pimlico, in the County of Middle-
sex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-sixth day of July, in the year of our Lord
One thousand eight hundred and fifty-four, in the eighteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John Chillcott Purnelle, Her special licence that I, the said John
Chillcott Purnelle, my executors, administrators, and assigns, or such others
as I, the said John Chillcott Purnelle, 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 Inven-
tion for "IMPROVEMENTS IN OBTAINING AND APPLYING MOTIVE POWER," upon
the condition (amongst others) that I, the said John Chillcott Purnelle, by

page_text: an instrument in writing under my hand and 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 John Chillcott Purnelle, do hereby
declare the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement thereof (that is to say):-
My Invention relates to certain new and improved arrangements of
mechanism or apparatus, by means of which motive power may be obtained
from atmospheric pressure in two ways; firstly, by compressing atmospheric
air in suitable vessels, and then employing the elastic force thereof for the
purpose of exerting pressure alternately upon the upper and under side of a
piston, working air-tight in a cylinder closed at top and bottom, and fitted
with valves acted upon by a tappet motion for opening and closing the said
valves when the piston is either at the top or bottom of the said cylinder;
secondly, by admitting atmospheric air in its natural state into an exhausted
cylinder, fitted with a piston and valves as before stated, and by adapting two air
pumps to such said cylinder, for the purpose of exhausting the air therefrom,
and forming a partial vacuum alternately above and below the piston, accord-
ing as such said piston is either at the top or bottom of the cylinder.
by previously exhausting the air from a vessel connected to the cylinder at
top and bottom by means of valves, and by alternately opening a commu-
nication with the top and bottom of the cylinder and the said vessel, and at
the same time admitting atmospheric air in its natural state to the reverse
end of the said cylinder. The nature of my said improvements, and the
method of carrying the same into practical effect, will, however, be better
understood upon referring to the Drawings accompanying these Presents,
and to the following explanation thereof.
Or
The first part of my Invention, or that which relates to compressing
atmospheric air and obtaining motive power therefrom, is exhibited at Figures
1 and 2 in the Drawing; Figure 1 being an elevation, and Figure 2 a plan
view, of an engine constructed according to my improved principle. I employ
for the purposes of this Invention a cylinder A, A, enclosing a piston similar
in construction to those employed in steam engines, and having the induction
passages B, B, made as short as possible, and communicating direct with the
cylinder at the top and bottom thereof. In connection with these air passages
is an air chest C, C, which is connected by short pipes D, D, to a pair of large

page_text: cylinders E, E, and F, F, which I call condensers.. These condensers are
open at the top, and are fitted with air-tight pistons. I connect theso
condensers with one, two, or more air pumps G, G, by means of pipes H, H,
which are fitted with valves or cocks, so as to shut off at any moment the
communication with either condenser. In obtaining motive power with the
above-mentioned apparatus, the air is first pumped into one of the condensers
(that marked E, for example,) by manual power, and when that condenser is
sufficiently charged according to the pressure required, the pump G (when
only one is employed) is then connected to a crank shaft I, I, attached to the
apparatus, and provided at one end with a fly wheel (not shewn in the Drawing),
and at the opposite end with a crank K, to which is attached the piston rod a
of the working cylinder A, A. And I propose to make the apparatus self-
acting, by placing a heavy weight upon the top of the piston of that condenser
which has been charged with atmospheric air. I then establish a connection
between the other or empty condenser F and the air pump G, and as the
second condenser F is thus being filled with atmospheric air, the first con-
denser E is being discharged of its compressed air, and when this said
condenser E is nearly exhausted, I then weight the piston of the other
condenser F, by which the weight will be taken off the first condenser E.
I then put the empty condenser E into communication with the air pump G,
and again fill this condenser with atmospheric air, and weight the piston, as
before stated, and in this manner and by these means I render the apparatus
self-acting, or nearly so.
The second part of my Invention, or that which relates to obtaining motive
power by exhausting a cylinder of the air which it contains, is exhibited at
Figures 3 and 4. In the arrangement of mechanism as exhibited at Figure 3,
I employ a working cylinder A, A, closed at top and bottom, and fitted with
an air-tight piston, as before stated with reference to the first apparatus. To
the top and bottom of this cylinder I connect air pumps B and C, and operate
therewith in the following manner:-Firstly, I exhaust the air from that part
of the cylinder which is (for example) above the piston, and simultaneously I
open a valve D, at the bottom of the cylinder, for the purpose of admitting
atmospheric air therein to below the piston, and thus impart upward motion to
the piston by reason of there being a partial vacuum above the same.
the piston has reached the end of its stroke, a self-acting tappet motion (not
shown in the Drawing) reverses the position of the valves D and E, by opening
the upper valve E and closing the lower one D, by which the pressure of the
atmospheric air will be exerted upon the upper side of the piston, and the air
exhausted from beneath it; and in this manner and by these means recipro-
When

page_text: manner.
cating motion will be imparted to the piston of the working cylinder and parts
in connection therewith, and may be transmitted from thence by spur gearing
or other suitable means, and employed as a motive power in any convenient
Another modification of this arrangement is exhibited at Figure 4
in the Drawing. Instead of connecting the air pump or pumps directly to the
top and bottom of the working cylinder, as in the last-mentioned arrangement,
I employ an exhausting or vacuum chest C, C, between the working cylinder
A, A, and the air pumps B, B, (one of which only is seen in the Drawing.)
This chest is connected with the cylinder A at top and bottom by means of
short pipes provided with valves a, a, which open and close alternately, and are
worked by means of a cam or excentric placed upon the main shaft. The air
pumps B, which are connected to the vacuum chest c, c, by short pipes b, b,
are to be worked by means of a small steam engine, or other power. The
working cylinder A, A, is provided at top and bottom with passages opposite
to those communicating with the vacuum chest, and furnished with valves c, c,
which open and close alternately in opposite directions to the valves a, a, which
connect the cylinder to the vacuum chest. The method of putting this
arrangement of mechanism in operation is as follows:-The air pumps are
worked so as to produce a vacuum in the chest C, which is then put into
communication with the top or bottom of the working cylinder A, (as the
case may be,) by opening one of the valves a, a, and the air from that side of
the piston expanding into the empty chest, causes a difference of pressure upon
the two sides of the piston, according to the perfection of the vacuum created
and maintained in the exhausting chest. This difference of pressure will
cause the piston to rise or fall, as the case may be. If the piston be raised,
the bottom valve c for the admission of air into the cylinder will be closed, and
also the top valve a, leading from the cylinder into the exhausting chest.
Simultaneously with the closing of these valves the opposite valves will be
opened, that is to say, the top valve for the admission of air into the cylinder
will be opened, and also the bottom valve leading into the vacuum chest. The
air from below the piston then expands into the exhausting chest, leaving the
atmospheric pressure on the top of the piston, and causing it to descend. I
may here remark, that the pneumatic apparatus herein-before described is
intended also to be used as a means of transmitting power from one engine to
another, and is peculiarly adapted for powder mills, manufactories of com-
bustible materials, warehouses, and other places where the steam engine would
be too hazardous, and where it is necessary to have the fire at a considerable
distance from the works. In lieu of transmitting power by means of com-
plicated shafts, straps, &c. as now practised, the engine may be worked by

page_text: simply connecting it, by means of air-tight pipes, with my pneumatic apparatus,
at any desired distance from the works; the pneumatic apparatus, being worked
by a steam or other engine, will transmit to the engine in the works any
required power, and thus prevent the possibility of the materials in the works
or other places coming in contact with the fire used for the steam boiler.
Having thus described the nature and object of my Invention of Improve-
ments in Obtaining and Applying Motive Power, together with the manner of
carrying the same into practical effect, I would remark, in conclusion, that I
am aware of motive power having been heretofore obtained both by compressing
atmospheric air into a vessel and by exhausting it therefrom, and therefore to
this principle I lay no claim; but what I declare my Invention to consist in,
and what I claim is, the peculiar arrangement of apparatus or mechanism
shewn in the Drawings and above described for effecting the said object.
In witness whereof, I, the said John Chillcott Purnelle, have hereunto
set my hand and seal, this Twenty-sixth day of January, in the year
of our Lord One thousand eight hundred and fifty-five.
JOHN CHILLCOTT PURNELLE. (L.S.)
Witness,
ALEX. PRINCE, Patent Agent,
4, Trafalgar Square, Charing Cross.