CERTAIN IMPROVEMENTS IN THE MEANS OF VENTILATION, MORE PARTICULARLY ADAPTED TO SHIPS' HOLDS, AND IN THE APPARATUS EMPLOYED THEREFOR
Year: 1873

page_text: PROVISIONAL SPECIFICATION left by Alfred Septimus Pratt at the
Office of the Commissioners of Patents, with his Petition, on the
9th April 1873.
I, ALFRED SEPTIMUS PRATT, of Cardiff, South Wales, Retired Surgeon,
Royal Navy, do hereby declare the nature of my said Invention for
"CERTAIN IMPROVEMENTS IN THE MEANS OF VENTILATION, MORE PARTICULARLY
ADAPTED TO SHIPS' HOLDS, AND IN THE APPARATUS EMPLOYED THEREFOR," to be as
follows:-
The Invention is designed more particularly for the purpose of ven-
tilating ships' holds, but may with advantage be applied to buildings for
ventilating the same or for other purposes.
In order that the improved ventilator may be clearly understood, I
will proceed to describe the application of the same as applied for
ventilating a ship's hold. For this purpose I provide upon deck a founda-
tional base plate having a central hole which has a screw thread or
other means of fixing, into which I screw or otherwise fix two vertical

page_text: hollow cylinders, one placed inside the other between the surface of the
inner and outer cylinder or casing, an annular space is formed, the lower
termination or base ring of the outer cylinder screws into the hole in
the foundation plate before mentioned, and the inner cylinder termi-
nates some little distance below this beneath the deck, the position of
the inner cylinder with respect to the outer cylinder or casing is defined
and maintained by means of internal collars provided with openings
or thoroughfares placed in the annular space and fixed in position
by strong set screws passed through the outside casing.
The upper
termination of the outer casing or cylinder is provided with a
groove or channel, and an overlap cylindrical projection, on to which
is placed my improved construction of "twin cowl" that is a cowl
having two thoroughfares, one for the entrance of fresh air which
leads direct into the internal portion of the lower fixed cylinder, and
the other for the exit of impure air which forms an annular thorough-
fare in direct communication with the annular space of the lower fixed
cylinder.
The base of the outer casing of this cowl is provided with wheels
or bowls, that are supported by and run in the circular groove or
channel formed in the upper termination of the fixed outer casing or
cylinder before mentioned, a similar arrangement of wheels or bowls
being also provided for supporting the internal cylindrical portion of
this cowl, the entrance and exit thoroughfares being turned in the
cowl from the vertical air shafts in opposite directions, and the
wheels or bowls supporting the cowl in its bearings as before men-
tioned are independently lubricated by means of ducts or passages
leading the oil from the outside of the cowl direct to the frictional
bearings of the bowls. The "twin cowl" is evenly balanced on its
seatings and has mounted above it a vane of sufficient superficial aria
to cause it readily to turn or rotate with the slightest breath of wind,
which is conveyed down the inner thoroughfare into the hold of the
vessel, the vitiated air at the same time ascending up the annular
space formed between the inner or outer cylinder is passed into the
outer atmosphere. Set screws placed in the rotating cowl working
in grooves are provided for the purpose of steadying the same in the
event of its being lifted from its seating by a sudden squall or from
other causes.

page_text: The lower fixed casing or outer cylinder is also provided with
stay rods for steadying its position upon deck. The whole of the
parts composing the cowl can be readily taken in pieces and stowed
away.