IMPROVEMENTS IN AIR COMPRESSING ENGINES.”
Year: 1872

page_text: LETTERS PATENT to William Easton and Frederick Tattersall, of the
Alexandra Foundry, Leeds, in the County of York, for the Invention
of "IMPROVEMENTS IN AIR COMPRESSING ENGINES.”
of “IMPROVEMENTS IN AIR COMPRESSING ENGINES.”
Scaled the 17th December 1872, and dated the 10th July 1872.
PROVISIONAL SPECIFICATION left by the said William Easton and
Frederick Tattersall at the Office of the Commissioners of Patents,
with their Petition, on the 10th July 1872.
We, WILLIAM EASTON and FREDERICK TATTERSALL, of the Alexandra
Foundry, Leeds, in the County of York, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN AIR COMPRESSING ENGINES," to
be as follows:-
-

page_text: a great length of foundation and engine house, and has the disadvantage
of the two pistons completing their stroke at the same time.
Now the compressing piston meets with more and more resistance
every inch of its advance, whilst on the other hand the steam piston is
losing energy, that is to say, the main work is done in the air cylinder
after half stroke when the steam is cut off and there is nothing but the
expansion and momentum stored in the fly wheel to overcome the
resistance.
Now we actuate the air compressing piston by a crank set at an
angle to the crank of the steam piston; the steam will then be exerting
its maximum force at the time in which there is the greatest resistance
in the compressing cylinder. The outlet valves from the air cylinder we
form of strong vulcanized india-rubber piping working against a per-
forated annular seating, and we cause water to circulate through this
pipe valve from a cistern placed above the compressing cylinder. The
compressed air enters this cistern so that the pressure within the tube
will never be less than the external pressure upon it.
The admission of steam is controlled by an air governor working
in connection with an ordinary governor. Air from the receiver is
admitted under the piston of the air governor, which is weighted so that
should the pressure in the receiver fall the piston will descend, thereby
admitting more steam, which it will continue to do until the receiver has
recovered its lost pressure.
The ordinary ball governor acts upon the same steam valve and comes
into operation when the maximum speed consistent with safety has been
reached. By this arrangement it will be seen that the receiver pressure
will be nearly constant and self-regulating, resulting in economy of
steam, as if air is not wanted the speed of the engine will immediately
fall, and vice versa.
SPECIFICATION in pursuance of the conditions of the Letters Patent, 30
filed by the said William Easton and Frederick Tattersall in the
Great Seal Patent Office on the 10th January 1873.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Tenth day of July, in the year of our
Lord One thousand eight hundred and seventy-two, in the thirty-sixth
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto us, the said William Easton and Frederick Tattersall, Her
special license that we, the said William Easton and Frederick Tattersall,
our executors, administrators, and assigns, or such others as we, the
said William Easton and Frederick Tattersall, our executors, adminis-
trators, and assigns, should at any time agree with, and no others, from
time to time and at all times thereafter during the term therein ex-
pressed, 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 AIR COMPRESSING
ENGINES," upon the condition (amongst others) that we, the said William
Easton and Frederick Tattersall, our executors or administrators, by an
instrument in writing under our or their hands and seals, or under the
hand and seal of one of us or them, 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.
г.
NOW KNOW YE, that we, the said William Easton and Frederick
Tattersall, 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:
This Invention has for its object improvements in air compressing
engines.
It has been customary in air compressing to place the compressing
piston on the same rod with steam piston. This arrangement requires a
great length of foundation and engine house, and has the disadvantage
of the two pistons completing their stroke at the same time.
Now the compressing piston meets with more and more resistance
every inch of its advance, whilst on the other hand the steam piston is
losing energy, that is to say, the main work is done in the air cylinder
after half stroke when the steam is cut off, and there is nothing but the
expansion and momentum stored in the fly wheel to overcome the
resistance.

page_text: absorb and convey away the heat generated by the condensation of the
air. The crank arms 6 and 62 are at right angles the one to the other,
so that at the times when the air is at its maximum pressure within the
air compressing cylinder, and is opposing the maximum resistance to
the air piston the steam piston is at mid-stroke and has the full pressure
of the steam upon it, and so is most advantageously circumstanced to
overcome the resistance. The passage of the steam into the valve chest
of the steam engine is controlled by an equilibrium valve; the stem of
this valve is marked h, and a weight or spring & tends constantly to lift
the valve; is a small cylinder containing a piston ", and the space
beneath this piston is in communication with the compressed air main,
so that the piston is pressed upwards by the air when the pressure is
sufficient to overcome the weights or springs m and k, which both act
in the same direction. Although weights are shewn in the Drawings,
in practice it is preferred to use springs. As the piston rises in con-
sequence of the increase of the pressure in the air main, it closes the
steam valve, and when the air pressure falls the piston / descends and
the steam valve opens. The engine is prevented from attaining a
dangerous speed by the ball governor n. This governor gives motion
in the manner shewn to a bell-crank lever o. The shorter arm of this
lever stands over the stem h of the steam valve, and comes into contact
with it whenever the air piston / would permit the steam valve to open
too widely.
The arrangements of the air valves at the ends of the air compressing
cylinder are shewn to a larger scale at Figures 4 and 5; Figure 4 is a
longitudinal and horizontal section; and Figure 5 a transverse section
taken on the line 1, 1, in Figure 4. p is the cylinder cover, in which are
openings p¹ forming a grating for the admission of air to the cylinder, these
openings are covered by an india-rubber valve q; r is a guard; p² are other
openings formed in the cover p for the escape of the compressed air
from the cylinder, they are covered by an india-rubber pipe s forming
a valve, and to prevent the heat of the compressed air injuring the valve
a stream of water is caused to flow constantly through it. The valve s
is contained in an annular chamber ³ formed in the cover p; this
chamber is closed by the cover plate t, and within the chamber the valve
is free to flap to and from its face; u is the compressed air outlet leading
to the air main. The tube valve 8 is secured to two pipes v, v, entering
the chamber q³, and these pipes pass through the bottom of the closed
water cistern wo, and one of the pipes rises higher than the other to

page_text: ensure a circulation through the ring valve. The upper part of the
*cistern w is in communication with the compressed air main.
Having thus described the nature of our said Invention, and the
manner of performing the same, we would have it understood that we
claim the arrangement of air compressing engines, substantially as
described, so that when the resistance of the air is greatest the steam is
exerting its maximum force.
We also claim the method of constructing the outlet valve, substan-
tially as described, so as to maintain a circulation of water through the
valve to protect it from the heat of the compressed air with which it is
constantly surrounded:
We also claim the method substantially as described of regulating the
speed of the engine in accordance with the pressure in the compressed.
air main and without risk of the engine attaining a dangerous speed.
In witness whereof, we, the said William Easton and Frederick
Tattersall, have hereunto set our hands and seals, this Ninth day
of January, in the year of our Lord One thousand eight hundred
and seventy-three.