1875.] Engineering. 399 
Dr. W. S. Carmichael thus describes his Breakwater Steamer :—The inven- 
tion is intended to modify the influence of the waves, &c., by covering certain 
generally exposed parts of vessels, and thereby to lessen tne dangers and in- 
conveniences of the sea. It consists of one general principle, viz., the defence 
of certain generally exposed parts of vessels by a covering. Ist. The defence 
of the sides and decks by sloping roofs, thereby enabling the vessel to retain 
a more horizontal position, and abating the dangers and inconveniences of the 
sea. 2nd. The defence of the screw or screws by a covering, thereby saving 
it or them from shot, &c., and enabling it or them to act with more effect. It 
consists of a hull up to the water-level, w L, somewhat like that of other ves- 
sels, except that the keel is straight and horizontal, the bow perpendicular, 
and it is perforated by one or more openings to be afterwards described. I 
propose that the vessel shall be nearly flat-bottomed, the sides below the 
water-level nearly perpendicular, and also that the heaviest parts shall be on 
the outside. Near the water-line, w L, or several feet above it, according to 
the size of the vessel, the sides all round slope inwards, become a sloping roof 
(s R) over the cabins (Mc, Fc, EC) and main deck (Mp), &c., at an angle of 45°, 
more or less, forming a breakwater on which the waves in rough weather may 
harmlessly expend their force, instead of dashing against nearly perpendicular 
sides, or washing the deck. These sloping roofs at the front of the vessel 
meet and form a sharp ridge, by which a wave at the front is cut in two. The 
upper part of this sloping roof, SR, may be made mostly of sliding panels, 
which may be pushed aside in calm weather, so as to render the main deck, 
MD, at such times nearly as open as in other vessels. Of course in the har- 
bour these panels will always be drawn aside, so as to leave room for the 
entrance and exit of passengers, the carriage of luggage and cargo, &c. 
Seven feet, more or less, above the main deck, mp, the sloping roofs end ina 
flat roof, G R, to allow the more violent waves to pass harmlessly from wind- 
ward to leeward, and, by being partly glazed, to give light to the decks below. 
The cabins below may also be lighted by the usual bull’s-eyes. Three or four 
feet, more or less, above the partly glazed roof, there is a smaller upper deck, 
U D, about half or a third of the size of the main deck, for captain, pilot, &c., 
and from which the vessel may be steered. This is supported on iron rods, 
braces, &c., not represented in the illustrations, and also by having a round 
enclosed staircase (St) at each end, leading down to the decks and cabins 
below. [I think this upper deck should be surrounded merely by a light 
railing, R, So as not to catch the wind. The movirg-power is generally one or 
two propellers, P, within or immediately behind one or two tubes, TT, 2 to 
8 feet in diameter, more or less, extending from stem to stern. If, on account 
of friction or other cause, these long tubes be found inexpedient, I propose 
two shorter tubes near the stern, either passing through part of the vessel, or 
altogether on the outside, or, finally, one tube from the stern with a branch 
passing through each side. By such means I expec that in calm weather 
such a vessel will advance through the water pretty much like other vessels— 
perhaps a little faster; that in rough weather the waves will rush harmlessly 
up the sloping roof and through the open space, os, to leeward, and that the 
windward side of the vessel will not be so inconveniently raised, both on ac- 
count of the heaviest parts being on the outside and on account of the shock 
of the waves being received on a sloping roof, which will causé that part to be 
depressed rather than raised; and my object is so to balance these forces, by 
varying the angle of the slope if necessary, as to keep the vessel steady. I 
expect, also, that the bow, by modifying the slope if necessary, will advance 
straight through a wave, instead of rising over it, and thus that the vessel will 
remain much more steady than is usual, and, as there will be less pitching, 
rolling, &c., that foundering and sea-sickness, and other dangers and incon- 
veniences will be less likely to occur, and as its course will be shorter, passing 
through instead of over the waves, that it will also be more rapid. An open 
space for the waves to pass through, and a high deck beyond their reach, is an 
old idea of mine revived by the late discussions about the means for preventing 
sea-sickness. I expect, also, that as the water reaches the screw more 
directly, this will have more power ; that the loss of power from slipping will 
VOL. V. (N.S.) 3E 
