A NEW OR IMPROVED CONSTRUCTION OF SCREW-PROPELLER AND, VESSEL MORE ESPECIALLY INTENDED FOR RAPID TRANSIT
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by Otto Wartmann at the Office of the
Commissioners of Patents on the 12th November 1883.
OTTO WARTMANN, of 91 Leadenhall Street in the City of London, Merchant,
"A NEW OR IMPROVED CONSTRUCTION OF SCREW-PROPELLER AND, VESSEL MORE
ESPECIALLY INTENDED FOR RAPID TRANSIT "
The principal object of my invention is rather the attainment of great speed, or
of lightness of propulsion, than of great carrying capacity.
My invention consists of an apparatus embodying what I consider to be a new
departure in water transport, the essential feature of which consists in utilizing
the scrow or scrows not only as a propeller or propellers, but as the source of
buoyancy, and means of support of the whole apparatus
The form of construction, and arrangement which I find best suited for carrying
my invention into practice consists of two or more long drawn tubular screws, the
cavity within which, or the material of which they are made, supplies the buoyancy
necessary for supporting and carrying the load, and the screw form of which causes
them, when they are revolved on their longitudinal axes to glide rapidly through
the water in the direction of their length, together with a superstructure supported
by the said tubular screws either above the surfaco of the water or submerged only
to a considerably less depth than it would be if not supported by the said screws.
In the construction of the screws any material having strength and buoyancy
may be employed, but I prefer to make them of sheet metal and hollow, nearly
cylindrical in shape, of about the same length as the whole apparatus-I find it
convenient to use three blades to the Screw and to give it a twist of about one
revolution in the entire length of the screw and I flatten or even hollow out the
surfaces of the cylindrical body of the scrow between the blades, so as to give a
section externally resembling a Polygon of as many sides as the screw has blades
and I prefer that each pair of screws should consist of one right and one left
screw.
I arrange the two or more screws with their longitudinal axes parallel and
horizontal and I fit the axles with journal boxes on which I support the
superstructure for carrying the load and driving power
I contemplate using considerable variety of arrangment so far as the super-
structure is concerned to meet the various requirements of the applications to

page_text: which my apparatus is adapted, for instance I propose to make some of small size
suitable for one individual only in which case the superstructure would consist of
littlo more than a seat with treadles and connections for driving-For Bathing
purposes I propose to construct them with a small dressing house and platform
with suitablo steps or other means of easy access to the water, and for dispatch
boats and the like services I propose to form the superstructure approximately in
the shape of a boat but so that it either shall not touch, or only dip very slightly
in the water-so as to offer a minimum resistance
It will readily be seen that a screw such as one of those described, namely of
nearly cylindrical shape but tapering towards the ends and with a screw propeller
blade wound spirally round it, when submerged, and caused to revolve on its
longitudinal axis will pass forwards or backwards through the water with very
little friction and almost without resistance, the sectional displacement being so
small, and as the propelling action is exerted by the screw throughout its entire
length it will, with a scrow of suitable pitch, glide rapidly through the water, and
two such screws connected as before described and revolved by appropriato
mechanism and motive power, will support the superstructure with great
steadiness and give a very high velocity.