POPULAR SCIENCE REVIEW.

STEAMSHIPS FOR THE CHANNEL PASSAGE.

By C. W. MERRIFIELD, F.R.S.

[PLATE XCII.]

THE A

HE ambitious schemes for the formation of harbours on one or both sides of the channel, and the still more extravagant proposals for tunnels and bridges, can hardly be considered as being of any immediate public interest. An estimate of the profit and loss account is sufficient to settle this part of the question to the satisfaction of any but an enthusiastic inventor or an interested promoter. Not that it would be at all safe to assert that such things will never be done, or that they may not be useful when done. Bigger bubbles than these, and blown with less soap, too, have been looked upon before now as solid investments by confiding capitalists. In all these schemes the dead-weight charge of interest on an enormous capital is quite out of proportion to any probable traffic return. It is easy enough to talk in general terms of absorbing the whole of the continental passenger traffic, increased by a safe and comfortable means of transit; but in the first place it is not possible to secure all or nearly all of it at renumerative rates, and secondly the whole annual number of passengers is very limited. We in England are apt to talk as if the channel passage were of even greater importance to Europe than to ourselves. The fact is the reverse. It is a primary matter to us, a secondary affair to France and Belgium, and a thing of very small concern to anybody else. It is the English who have most to gain by it; and on England, therefore, in some shape or other, the charge will ultimately fall. In so far as they depend upon passenger traffic across the channel, large engineering works cannot be renumerative. It is true that a company may be promoted, and that it may make the fortune

of the engineer and of some of the early directors; and it is also true that if the works succeed in their material intention— of which there is, perhaps, almost an even chance—the shareholders will enjoy the satisfaction of having conferred upon their country a benefit as enduring as their structures. Their patriotism will be its own reward.

More reasonable projects are those which have in view the use of the existing harbours, either as they now are, or with such improvements as the local authorities could be induced to make without large contributions from the companies; and which propose to substitute large, safe, and comfortable vessels, with special provisions for preventing or alleviating sea-sickness, for the present mail steamers-passenger steamers it would be absurd to call them. I make this remark advisedly. The boats are admirably suited to the mail service, and to the light goods traffic, especially in fruit and fish, which take up so much of their available deck space. But a fishing lugger, with its hold cleared for a sailing party, or a tug chartered for a cheap trip, usually carries its passengers with less discomfort than the best means which English enterprise has furnished for the most important sea-ferry in Europe. I know of nothing more disgusting than the main cabin of these channel steamers on a wet night, unless it be the ladies' cabin; and it is a marvel to me how a nation which prides itself on the care with which it protects women from all coarse contact, can submit to see gentlewomen exposed to crowding and filth in the midst of which decency is scarcely possible, and delicacy is out of the question.

Apart from the discomforts of overcrowding, small boats have much more motion than large ones; and it is a general result of experience that, under like conditions in other respects, the sea-sickness varies inversely as the size of the ship, being very severe in small vessels and scarcely felt in very large ships. The ailment itself appears to be of a rather complex character, both in its causes and its effects, and the exact relation of each separate cause and effect does not appear to have as yet been completely disentangled from the others. That its ultimate cause is solely and entirely the motion of the ship, there is no doubt at all; but physiologists are by no means agreed as to the chain of operation, or the intermediate detail which separates the primary cause from its final result. Some attach more importance to the changes of mechanical pressure induced by the varying motion; others to the optical effect reacting on the stomach through the brain. My own opinion is that with unseasoned travellers either of these causes is alone sufficient to produce the sickness, and that they are generally in simultaneous operation; but that the mechanical

is the leading one. We know that there is mechanical cause. When a man is standing or sitting, the weight of his intestines is taken by the pelvic bones, and through the reaction of these there is but little upward pressure against the stomach, diaphragm, and liver, which are supported by the scaffolding of the spine and ribs. When this reaction is prevented by the ship sinking from under one's feet, the elasticity of the intestines is no longer controlled by gravity, and they are free to press upwards against the stomach and other organs. Elsewhere than at sea, we know that this relief of weight does produce uneasiness. A qualm is felt in the descent from a swing, and in jumping feet foremost from great heights, while no such feeling is experienced in a high dive taken head foremost. The alternation of this pressure is quite a sufficient cause of irritation to produce sickness. A very remarkable confirmation of this view is afforded by the fact that sea-sickness in women occasionally presents different and far more serious symptoms than it is usual to meet with in the case of men.

Whether the optical effect be alone sufficient to produce seasickness in an ordinary person may be open to doubt; but there is no denying that it very much enhances whatever effects may be due to the mechanical causes, especially the distressing giddiness which is a frequent symptom. Giddiness is not solely due to optical causes. I have seen a child make itself sick by turning round and round with its eyes shut. I draw from this the further inference that the amount of motion necessary is not very great, if it be sufficiently long continued.

The upward and downward motion on board a ship is due not only to the upward and downward movements of the ship as a whole, but also to the rocking, whether rolling or pitching; just as in a see-saw the ends of the plank move up and down, although the plank, as a whole, has no vertical motion, seeing that it turns on a fixed pivot. There is no such fixed pivot in a ship: every point of it moves; but at the extreme ends and sides this see-sawing is added to the unsteadiness of the middle part of the ship, which accordingly seems to be comparatively still.

The uneasiness of a ship is greatly enhanced by the continually varying mixture of heaving, rolling, and pitching, which prevents our adapting ourselves to the motion in the same way that a little muscular action, combined with the selection of a suitable attitude, enables us to meet a simple oscillation like that of a swing. Any mechanism which simplifies the motion will therefore probably tend to reduce seasickness.

One point, which is common to all the improved designs of ships for the channel passage, is large size. The harbours on

the French coast impose considerable restrictions upon this, especially as regards draught of water. At or near low water, six or seven feet is all that can be depended upon, and this only in still weather. With large boats, accordingly, any idea of a service at fixed hours, irrespective of tide, must be abandoned, and there will also be certain rough days in which small mail steamers can enter the harbours when the larger boats cannot do so with safety. There can be no question, however, that no real improvement can be effected without larger boats. Three or four years ago the Society of Arts offered a prize for a model of good arrangements for deck passengers aboard vessels of the same size as those now in use. Of more than twenty models submitted for adjudication, only three or four complied with the conditions laid down as to size, and these three or four showed no real improvement. Under these circumstances no prize could, of course, be awarded; but it was quite evident to the writer (who was one of the committee), that the limitation as to dimensions rendered a good deck arrangement impracticable. The only really improved designs postulated increased dimensions.

Of the schemes which have been laid before the public, while there are several which aim at reducing the amount of motion, and of consequent sea-sickness, by due proportion and dimension, there is only one which takes special and direct means of securing that the passengers shall not partake of the motion of the ship. That scheme is Mr. Henry Bessemer's.

Most of our readers must have noticed the way in which a ship's compass, and the cabin barometer, are suspended-in a sort of universal joint, commonly called jimbals. The idea of suspending a cabin in this way is no novelty; but there were several practical difficulties in the way of carrying it out on a large scale. The double pivoting makes rather an insecure connection between the large moving weight and the structure of the ship. There are also difficulties about getting in and out of such a cabin. Moreover, there is no really fixed point in a ship at sea, and the motion of the point of suspension reacts upon the suspended mass, which thus acquires an oscillation of its own. Oscillations have a regular rhythmical period, like a musical note, and every freely suspended body has its own note, or periodic time. If it happens that the periodic time of the suspended cabin coincides, absolutely or approximately, with that of the point of suspension, there may be an accumulated roll far in excess of that of the ship itself. A freely suspended cabin, therefore, would not answer the intended purpose.

The point of Mr. Bessemer's invention consists in the steadying of the cabin being controlled by hand instead of acting

automatically. A man sits at a lever, by which he commands hydraulic machinery which adjusts the position of the cabin relatively to the ship. He has a spirit-level in front of him, by which he keeps the level, just as the helmsman keeps his course by means of the compass. This retention of controlling power appears to me to be the chief point of the invention. It is by no means the only point in the actual design, about which there are many features, constituting in their entirety a very bold and original as well as an ingenious design.

The steam-ships which are to carry this swinging cabin have been designed by Mr. E. J. Reed, C.B. The following description is taken from information furnished by the designers :

"These steam-ships are double-ended, and are propelled by four large paddle-wheels, two at each side. The ends are kept low for the purpose of reducing the motions produced by the action of the wind and of the sea, and the middle portion is made sufficiently high to enable them to steam at a high speed against the worst seas they will have to meet. A rudder is fitted at each end, with means for locking, so that the ship will be able to steam in either direction, and will not require to be turned round in harbour.

"Each steamer will be 350 ft. long, 45 ft. wide along the deck beam, and 65 feet wide across the paddle-boxes. She will draw 7 ft. 6 in. of water, the same as the present steamers, and will be propelled at a speed of twenty miles per hour, by two pairs of engines of the collective power of 4,600 horses. The centres of the two pairs of paddle-wheels will be 106 ft. apart.

"The great peculiarity, however, of these ships is that each will contain a large saloon, designed by Mr. Bessemer, suspended in the middle of the ship in such a way that it can be moved about a longitudinal axis parallel to the keel. The motion of this saloon, which would be set up when the vessel rolled if left free to move, will be governed by a hydraulic apparatus, and will be completely under the control of one man, whose duty it will be to keep the floor of the saloon, under all circumstances, in a line with a spirit-level.

"The passenger accommodation will consist of the Bessemer saloon, which is 70 ft. long, 35 ft. wide, and 20 ft. high; a fixed saloon at one end between decks, 52 ft. long; and a line of fixed cabins on each side of the ship, between the paddleboxes. This line of fixed cabins will occupy a total length of 150 ft., and include a refreshment-cabin, smoking-cabin, lavatories, and small deck-cabins. The luggage will be stowed in the hold at the opposite end of the ship to the passengersaloons. The Bessemer saloon will form by far the finest cabin that has ever been fitted in a ship. Its great size and height