The inner boat, being carried by the outer boat, does not come in contact with the water, and can offer no resistance to its speed or momentum.
“The inner boat is similar in construction and size to the outer, and constitutes the living apartments and affording a place to carry all the necessary appliances according to the usage of the boat. At a suitable distance from each end of the inner boat two turrets are constructed that rise at right angles to the inner boat to a distance of a foot above the greatest diameter of the revoluble hull. So that when running awash only a very small portion of the boat is exposed to view, and no vital parts.
The rear turrets constitute a pilot house and also afford an opening for ingress and egress to the inner boat, the pilot house being telescoped in the turret and closed with watertight fastenings when boat is submerged. The lower ends of the turrets are made flat and thin, and extend downward to a point sufficient to hold a solid iron keel, which allows the revoluble hull to turn between it and the inner boat. This keel steadies the boat latterly and adds stability to the inner boat, being rigidly connected at both ends.
“If in the rapid rotation of the outer shell the inner boat may have any inclination to deviate from a level, by working the hydroplanes of the one side adverse to those of
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