IMPROVEMENTS IN ENGINES MOVED BY THE PRESSURE, ELASTI- CITY, OR EXPANSION OF GAS OR AIR, BY WHICH A GREAT SAVING OF FUEL WILL BE EFFECTED
Year: 1826

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, 1, ROBERT
MEIKELAM, of Furnival's Inn, Holborn, and of Judd Street, in the County of
Middlesex, Engineer, send greeting.
WHEREAS His most Excellent Majesty King George the Fourth, by His
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Sixth day of June, in the seventh year of His reign, did, for
Himself, His heirs and successors, give and grant unto me, the said Robert
Meikelam, His especial licence, that I, tho said Robert Meikelam, my
exccutors, administrators, and assigns, or such others as I, the said Robert
Meikelam, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times during the
term of years therein expressed, should and lawfully might make, use, exercise,
and vend, within England, Wales, and the Town of Berwick-upon-Tweed, my
Invention for "IMPROVEMENTS IN ENGINES MOVED BY THE PRESSURE, ELASTI-
CITY, OR EXPANSION OF GAS OR AIR, BY WHICH A GREAT SAVING OF FUEL WILL
BE EFFECTED;" in which said Letters Patent there is contained a proviso oblig-
ing me, the said Robert Meikelam, by an instrument in writing under my
hand and seal, particularly to describe and ascertain the nature of my said
Invention, and in what manner the same is to be performed, and to cause the
sane to be inrolled in His Majesty's High Court of Chancery within two
months next and immediately after the date of the said 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
Robert Meikelam, do hereby declare that the nature of my said Invention,

page_text: and the manner in which the same is to be performed, is described and ascer-
tained as follows, that is to say :-
The cylinder is to be constructed in the usual form and with the usual mate-
rials, and is to be finished in the inside as the piston cylinders commonly are.
To the bottom or top of this cylinder a pipe or pipes are fitted, communicating
with it internally. The piston is formed hollow, having one or more perforations
on its upper and under side, fitted with valves of any of the common kinds, so
adjusted that one shall be open when the other is shut, and by this means
opening a communication with the cylinder either above or below the piston.
The box forming the piston is made with two or more divisions formed of
copper, and as thin as possible, each division communicating with the pipe or
pipes attached to the piston, or forming its stem, the spaces between each divi-
sion communicating with each other, and the cylinder by the valve open-
ings on the upper and under sides of the piston. The pipes attached to the
piston have one or more valves, each constructed to open upwards in the one
pipo and downwards in the other, so that a current may be maintained in
one direction only. These pipes communicate by another pipe with a boiler
or retort, and each pipe has a cock or valve opening to the atmosphere, ending
with a female screw, to which a pump may be screwed on occasionally. The
pipes fixed to the piston move upwards and downwards in the pipes attached
to the cylinder through stuffing boxes, so as to allow of a free motion with a
joint perfectly steam tight. The rod from which motion is communicated
from the piston to any machine is perforated, and fitted with a small forcing
pump, the rod having a tappet so adjusted as to be acted upon by the rise and
fall of the piston. This perforation is continued by a short pipe into the cavity
of the piston, terminated by several small holes to distribute the fluid with
which it is filled in minute jets upon the surfaces in the cavity of the piston.
This pipe may be placed within the greater pipes from the piston, and made
steam and water tight by the usual methods, having its pump and cistern out-
side of the pipes fitted on the top of the cylinder. The cylinder is surrounded
with a casing of metal. Into the cavity formed hot fluid is introduced from the
boiler, and, still further to economise the heat, this is also surrounded with another
metal inclosure, inclosing in the interstice pounded charcoal or some other
slow conductor of caloric. The whole apparatus of the model was inclosed in
the boiler, but this arrangement may be varied, and the boiler or retort may
be detached. The retort, and pipes connected with it, and the divisions in the
cavity of the piston, being filled with fluid by the cock or valve in the boiler,
and in the other parts by a pump placed on the pipes attached to the cylinder,
that portion of fluid (linseed oil was used in my trials, but any other may be

page_text: employed of which the temperature can be raised to the required degree, or
any semi-fluid metal,) circulating in the pipes speedily raises the temperature
of that in the cavity of the piston. The piston being supposed at the top of
the cylinder, and the valve in its upper part open, a small quantity of fluid
being distributed by the forcing pump upon the heated surfaces in the cavity
of the piston, a vapour is produced, which, escaping through the valve into the
cylinder, depresses the piston; when the piston has approached the limit of its
movement, the valve on the upper side of the piston is shut by a catch, and
that on the lower side opened, and the communication is then between the
cavity of the piston and the underside of the cylinder;- another portion of fluid
is thrown upon the heated surfaces in the cavity, and the vapour issuing from
the valve on the underside of the piston raises it to the top of the cylinder; and
thus, alternately, during these movements, a constant circulation of the heated
fluid is going on between the boiler and the interior of the cavity of the
piston, that is, it is forced up one pipe (or division of a pipe) through a valve or
valves opening in that direction, down the other pipe, or division of one,
into the boiler or retort. The combustion of an inflammable gas may be
applied to produce vapour in this apparatus, by heating its interior or
exterior surfaces. A pipe containing the gas, and another containing common
air, each having a valve at its upper extremity, and a gasometer and
forcing-pump at the opposite ends, a moveable pipe is placed directly over
that containing the gas, open at all times to the atmosphere, and in which
a small gas flame is kept constantly; the cavities of the piston being filled
filled with inflammable gas and air, the mixture is ignited by withdrawing the
cover from the gas flame by a lever attached to it, and communicating in the
usual manner with the outside of the cylinders, a jet of water is then introduced
through the pipe already described, and, the valves being opened either on the
upper or under sides of the piston, it is raised and depressed accordingly. In
this description the apparatus is supposed to be used with steam of a low
temperature and a common condenser, and its apparatus is connected with it
so as to form a vacuum above or below the piston before the commencement of
each alternate movement. That used in my model, in which the vapour was
generated from ether, was formed to condense by contact by two plates of metal,
set at a distance of about the of an inch from each other, and immersed in a
vessel constantly replenished with cold water. When used as a high-pressure
engine, the communication with the two ends of the cylinder is made in the
usual manner, and the condenser is omitted. All the parts of this machine are
formed in the mode usually followed by other mechanics, and the valves, pipes,
cocks, cylinders, are similar in their form, action, and manner of being attached

page_text: to each other with those employed in other engines; the piston and piston rod
have also been formed hollow, and vapour was generated on the inside of the
cylinder in some of the earliest engines. My improvement consists generally
in excluding the heating fluid or semi-fluid from the interior of the cylinder,
except as enclosed in the piston, and generating vapour from heated surfaces
within tho piston, or from the outer surfaces of the piston, in whatever way
this piston is heated, either by fluid, semi-fluid, or solid heated bodies, or com-
bustibles inserted within the piston.
Inrolled the same Fifth day of August, in the year above written.