1875.] Geology. 401 
not be so great; and that the screw will a& more, as if it were rotating in an 
unyielding substance, or pumping the water from stemto stern. The screw will 
also be less exposed to danger from ropes, chains, torpedoes, shot, &c. When 
the wind is favourable, water sails may be used, or other sails with jury masts. 
I think that flat-bottomed boats built on this plan might be useful for landing 
passengers through a surf, as at Madras, and a modification of it for life-boats. 
In these cases a screw driven by a small steam-engine or strong arms would 
be necessary. Such a plan might enable fishermen to bring themselves and 
cargo home in safety instead of losing both by being swamped in a sudden 
storm. Such a plan in sailing vessels might save sailors and deck cargo from 
being washed overboard, as sometimes happens, and the vessel itself from 
foundering. In this case a high deck would be necessary, either on the top of 
the sloping roof, or made by conneéting the fore, main, and mizen tops, or by 
both plans. When I explained my invention to a friend of mine here, he said 
—‘* Would you have your vessel lie on the surface of the water like a log of 
wood ?”’ He expressed my intention almost exa@ly. I would have my 
vessel, in rough weather, lie on the water, or rather advance through it, like a 
log of wood sharpened at the front, the water washing every exposed part of 
it except the high upper deck. Taking this view of it, there seems to me 
some similarity between it and the catamaran of Madras: this is merely three 
logs lashed together; upon it one, two, or three men kneel, and paddle through 
the surf when no other craft can venture. In this case the catamaran and the 
legs of the natives washed by the waves may represent the body of my vessel 
and its roofs; the heads, bodies, and arms of the natives may represent my 
upper deck and its occupants. Another objection is that a violent storm would 
soon wash away all my sloping roof. This is easily answered: the first 6, 8, 
or 10 feet above the water-line must be made as strong as the bulwarks, or 
rather the sides of other vessels. Beyond 8 or to feet the force of the waves 
is not against the sloping roof, except the mere weight of the water, but ob- 
liquely upwards at the angle of the slope; and I would have the movable 
panels only about 6, 8, or 10 feet above the water-level. Another objection is 
that straight lines are wrong, because seamen liked a lively boat. My object 
is to prevent liveliness. Another is, that there would be a choking ation in 
the tubes. This seems to me a question of power: increase the power and 
strength of materials, or diminish the size of the screw. The engraving is 
meant to represent a transverse vertical section through the after staircase, St, 
and a longitudinal vertical centric section, both about ,},th of real size, rinch 
representing about 25 feet. vr T, tube or tubes for propeller or propellers ; 
WL, water-level; McC, FC, EC, main, fore, and engineers’ cabins; MD, main 
deck; sR, SR, sloping roofs, the bow and stern slooping roofs not lettered ; 
GR, flat roof, partly glazed; 0 s,OS, open space for waves to pass through 
below upper deck; vu D, upper deck; RR, railings round upper deck. 
GEOLOGY. 
Physical Geology.—Professor Prestwich, in discussing the origin of the 
Chesil Bank, has concluded that the shingle was originally derived from the 
cliffs between Budleigh Salterton and Lyme Regis, and that it was propelled 
eastward by the action of wind-waves, due to the prevalent and heaviest seas. 
Referring to the raised beach of Portland, he pointed out that therein were to 
be found all the materials noticed in the Chesil Bank. Remnants of this beach 
could be traced in or on the present cliffs, at intervals from Brighton to the 
coast of Cornwall, and it was to the destru@tion of this old beach that the 
pebbles in the Chesil Bank were largely due. 
The rocks of the mining distri&s of Cornwall have been lately described by 
Mr. J. A. Phillips. He observes that the clay-slates of Cornwall differ mate- 
rially in composition, but no rearrangement of their constituents could result 
in the production of granite. 
Speaking of the origin of continents, Prof. Seeley stated (at a recent meeting 
of the Geological Society) that remembering that the lifting power of the moon 
coresponded to about 1-250,oooth part of the earth’s weight, and that the sun 
