IMPROVEMENTS IN THE CONSTRUCTION AND MODE OF LAUNCHING SUBAQUEOUS WAYS
Year: 1869

page_text: PROVISIONAL SPECIFICATION left by Zerah Colburn at the Office
of the Commissioners of Patents, with his Petition, on the 24th
August 1869.
I, ZERAH COLBURN, of Number 37, Bedford Street, in the City of
Westminster, and County of Middlesex, Civil Engineer, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN THE
CONSTRUCTION AND MODE OF LAUNCHING SUBAQUEOUS WAYS," to be as
follows:-
A tube of cast iron, wrought iron or steel, or of any combination of
those materials and protected or not with an external covering of any
material or materials suitable for preserving the iron or steel from corrosion
or abrasion is to be commenced on either shore or in a dry dock adjacent
to the shore. The riverward or seaward end of the tube is to be firmly
closed so as completely to prevent all ingress of water under the pressure
of the greatest depth of water to which the tube is to be lowered. The
tube should be so made as to have a preponderance of weight at its lower
side, so as to preserve its intended position when under the influence of
tidal or fluvial currents, or when as might happen it was caught by a
dragging anchor. The whole construction of the tube being carried
on out of water continuously and in any convenient lengths, even to a

page_text: "
mile or more, it would when such a length was completed be floated to
the extent of that length across the river or channel to be crossed.
The tube should be of such launching weight as to be somewhat
heavier than the weight of the water displaced by its submersion, but
it should at the same time be buoyed at intervals by adjustible buoys,
so as to keep it clear of the bottom whenever a fresh length was being
launched riverward or seaward. The launch of a "length," the "length
being the linear addition made to the continuous tube subsequent to
the next previous launch, would thus involve merely the floating hori-
zontally forward of all that portion of the tube already constructed,
and to the extent of the "length" completed since the preceding launch
or floating forward. The tube, whatever its inclination downward and
to whatever depth of water it might be lowered under the control
of adjustible buoys, would be in perfect equilibrium so far as hydro-
static pressure was concerned, and would require no power to force it
forward beyond that merely necessary for its slow motion through the
water.
In order to preserve the proper direction of the tube various expe-
dients might be adopted dependent upon the width, currents, &c. of the
river or channel to be crossed. If accurately steered a steam tug would
answer the purpose, but for long distances the tube barely clear of the
bottom of the channel would be pulled through the water by wire
ropes or chains made fast either to moorings or to the opposite shore or
coast. Thus a wire rope laid between France and England might pass
through a stuffing box in the closed seaward end of the tube, and by
winding this rope or chain upon a windlass within it would insure not
only the requisite advancing power but also the intended direction. The
tube would be constructed so as to possess a certain amount of flexi-
bility sufficient to adapt it to the gradients to be traversed, and it would
be generally found convenient in laying it to keep it as near the bottom
as possible without actually touching it. To this end the buoys would
be controlled through wire ropes working in stuffing boxes in the shell
or thickness of the tube itself, a buoy being allowed a further or less
distance from the tube by letting out or winding in the wire or other
rope attached to it. When the tube reaches the opposite or objective
shore or coast and its closed end is wholly above high water, the closed
end will be removed and dry communication throughout the subaqueous
way will thus be complete, although the subsequent works of lining
and of making a permanent or other way would remain to be per-

page_text: formed. The buoys which had served to partly float the tube would be
removed and the whole work allowed to rest upon the bottom. The
tube may
be supported wherever necessary on screw piles worked
through stuffing boxes on the inside, and all stuffing boxes may be
finally closed by a plan analogous to that well known as Mr. Alfred
Upward's for drilling water mains and gas mains under pressure. The
tube might also be commenced and carried out from both shores, the
ends forming respectively a "male" and "female" socket, which could
be brought together by various means, among these being a wire rope
leading through a stuffing box in the centre of each head properly
brought together, and under pressure the heads might be removed and a
permanent joint secured. By this plan of construction all the work of
making the tube would be performed on shore, and out of danger to
the workmen from any influx of water. But few attendents would be
required within the tube during the time of working it forward, and with
proper arrangements even twenty miles of submarine tube might be put
together and worked across in a comparatively short space of time.