IMPROVEMENTS IN COMPOUND MARINE ENGINES
Year: 1870

page_text: LETTERS PATENT to Thomas Blackwood, of Port Glasgow, in the
County of Renfrew, North Britain, Engineer and Shipbuilder, for
the Invention of “ IMPROVEMENTS IN COMPOUND MARINE ENGINES."
Sealed the 2nd August 1870, and dated the 25th February 1870.
PROVISIONAL SPECIFICATION left by the said Thomas Blackwood at
the Office of the Commissioners of Patents, with his Petition, on
the 25th February 1870.
I, THOMAS BLACKWOOD, of Port Glasgow, in the County of Renfrew,
North Britain, Engineer and Shipbuilder, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN COMPOUND MARINE ENGINES,"
to be as follows, that is to say :-
:-
This Invention relates to the class of compound marine engines now
coming largely into use in which one high-pressure cylinder is combined
with one low-pressure cylinder. In such engines as hitherto constructed
difficulty is experienced in effecting a start when they happen to have

page_text: come to rest with the parts in certain positions, and the present Invention
consists in providing certain simple and convenient appliances whereby
such difficulty can be entirely removed. For this purpose an additional
valve face is provided in the valve casing of the low-pressure cylinder,
or in a space or passage leading thereto, and this valve face has in it
two ports, one of which communicates with the condenser or with the
atmosphere, whilst the other communicates with the passage leading the
steam from the high-pressure cylinder after it has acted therein. A
common slide valve is applied over the ports, and in ordinary working
is only over the first-named port, but when the adjustment is required
for starting this valve is shifted to put the two ports in communication,
and at the same time-shuts-off-from-the-low-pressure casing the exhaust
steam from the high-pressure cylinder. Combined with this arrange-
ment a small branch pipe is led from the steam pipe or from the high-
pressure casing into the low-pressure casing, and being fitted with an
adjustable stop valve allows of a regulated supply of steam being
admitted to work the low-pressure cylinder. The two cylinders are by
these means temporarily separated and made to work like those of
ordinary engines without the least difficulty in starting from any
position. Instead of the slide valve herein-before referred to any con-
venient valve may be used that will alter the intercommunication of the
passages in the manner herein-before explained.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Blackwood in the Great Seal Patent Office
on the 24th August 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
BLACKWOOD, of Port Glasgow, in the County of Renfrew, North Britain,
Engineer & Shipbuilder, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fifth day of February, in the
year of our Lord One thousand eight hundred and seventy, in the thirty-
third year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Thomas Blackwood, Her special licence
that I, the said Thomas Blackwood, my executors, administrators, and

page_text: assigns, or such others as I, the said Thomas Blackwood, 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
COMPOUND MARINE ENGINES," upon the condition (amongst others) that I,
the said Thomas Blackwood, my executors or administrators, by an
instrument in writing under my, or their, or one of their hands and
scals, 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 Thomas Blackwood, 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 and
by the following statement in writing, reference being had to the accom-
panying Drawings, that is to say:—
My said Invention relates to the class of compound marine engines
now coming largely into use in which one high-pressure cylinder is
combined with one low-pressure cylinder. In such engines as hitherto
constructed difficulty is experienced in effecting a start when they
happen to have come to rest with the parts in certain positions, and my
present Invention consists in providing certain simple and convenient
appliances whereby such difficulty can be entirely removed. For this
purpose I apply an additional valve in connection with the passage
ordinarily leading from the exhaust port of the high-pressure cylinder to
the valve casing of the low-pressure cylinder, which additional valve
controls that passage and also an additional passage leading to the
condenser or to the atmosphere. When the adjustment is required for
starting this additional valve is shifted to put the high-pressure exhaust
passage in communication with the condenser or atmosphere, and at the
same time shuts the communication to the low-pressure valve casing.
Combined with this arrangement a small branch pipe is led from the
steam pipe or from the high-pressure valve casing into the low-pressure
valve casing, and being fitted with an adjustable stop valve allows of a

page_text: regulated supply of steam being admitted directly from the boiler to
work the low-pressure cylinder. The two cylinders are by these means
temporarily separated and made to work like those of ordinary (non-
compound) engines without the least difficulty in starting from any
position.
And in order that my said Invention and the manner of performing
the same may be properly understood, I have hereunto appended a Sheet
of explanatory Drawings to be herein-after referred to, and representing
parts of a set of inverted cylinder compound marine engines as provided
with a suitable, simple, and convenient modification of appliances for
carrying out my Invention. I do not however-restrict myself to this
-modification, as many other equivalent modifications will readily occur
to those practically acquainted with the construction of marine engines.
Figure 1 is a longitudinal vertical section through the cylinders, but
with a part in elevation; Figure 2 is a horizontal section, and Figure 3
is an end clevation with a part in transverse vertical section as at the
line A, B, C, D, E, in Figure 2. The high-pressure exhaust port 1 leads
into a space 2 at the side, having valve openings 3, 4, fitted with seats to
suit the opposite sides of a disc valve 5 fixed on a spindle 6 which
passes out through a stuffing box, and has any convenient hand adjusting
gear applied to it externally. The upper valve opening 3 communicates
with the low-pressure casing 7, whilst the lower valve opening 4 com-
municates with a space 8 connected by a pipe or passage to the
condenser. The valve 5 is shown as closing the lower opening 4 as it
does when working the engines on the "compound" system; but when
complete control is required for starting or for reversing the valve 5 is
shifted up to close the upper opening 3 and open the lower one 4, and at
the same time steam is admitted from the high-pressure casing 9 (or it
might be from the steam pipe 10) by a stop or regulator valve 11, and
through a branch pipe 12 into the valve casing 7 of the larger or
low-pressure cylinder.
Having thus particularly described my said Invention, and the
manner in which the same is to be performed, 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, the providing of two cylinder compound marine engines with
valvular details and a branch steam pipe arranged so that the cylinders

page_text: 5
In witness whereof, I, the said Thomas Blackwood, have hereunto
set my hand and seal, this Twenty-second day of August, in the.
year of our Lord One thousand eight hundred and seventy.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
THOMAS BLACKWOOD. (L.S.)