nozzle on each side, with a moveable month,
the vessel could be made to move forward or
backward, or to turn round, at pleasure. It is yet
a disputed point how much more power is lost
by the pump than by the screw; but when we
remember how many years we have been by
slow processes getting the screw to its present
condition of utility, there is little doubt that
further experiments will give important results
with the pump. The same screw that we apply
at the stem of a vessel wherewith to propel,
serves equally well to raise water when applied
as a pump, if the sides be inclosed to form a
bucket.
One thing is certain, the stem screw is much more out of the way than the side paddles or screws, and the pump in the bottom is still more out of the way than the stem screw. There is nothing to get foul in the case of the pump, and in a war-ship even something of speed might be sacrificed for such an important object.
While we use explosive boilers, it is worth while to consider how to minimise the danger if an explosion does take place. The usual course of explosion is upwards, like gunpowder; and therefore if the boiler be confined within firm wrought-iron walls, there need be no communication to the boiler space save by the furnace and ash-pan doors; and in such case the stokers might be kept comparatively cool by constant currents of air passing over and around them, in contra- distinction to the present very common practice of nearly roasting them alive. Apart from the cruelty to the men, this is no trifling matter in point of safety to crew and passengers. No man can do his work well and thoroughly while his bodily sensations are those of pain and discomfort, and even inspection cannot be well performed with im willing workmen. We have no right, as we are not despots, to roast people alive in a stoke-hole, and shall infallibly get punished for it, by their doing what they ought not to do, and leaving undone that which they ought to do. Examination of valves and all other matters can be provided for, without having the heated boiler in close contact with the stokers. A war-ship depending wholly on the management of her steam, would be in great peril if the condition of her boilers were such as to drive the men away at intervals to get fresh air, as we so commonly see in our river passenger- steamers.
Supposing the walls of the boiler space to be carried up a sufficient height above the deck like a square chimney, and roofed over only sufficiently strong to keep out wind and water, the probable result of an explosion would be similar to that of a gun placed vertically. It would blow the steam and all fractured portions upwards, with little mischief and without permeating horizontally, and scalding the men; and the boiler could be arranged so as to make the upper portion the weakest part, thus determining the fracture to the line of safety, if burst by over pressure. It is obvious that in the construction of boilers the same principle ought to obtain as in the construction of the vessels, viz., to get rid of rivets, and to substitute solid welding, even if the question involved a change of form in the boilers, so arranging them as to make all parts capable of being welded.
In all vessels there is one line of floatation or displacement which involves the least amount of retardation through the water. In the ordinary arrangement of vessels this -varies in proportion to the consumption of provisions and water by those on board. In steam-vessels, the item of coal-consumption makes a much more serious difference. In the Great Eastern this difficulty is met by pumping sea or other water into the various compartments to replace the weight consumed. From the time that iron tanks were used instead of water-casks this plan has been resorted to, but in steam-vessels, with fixed pumps and pipes, and with steam to do the work, the old plan of ballasting by shingle or gravel may be dispensed with. Water ballast is the most convenient arrangement, and, placed in close cells so that it cannot shift, it is the safest of any kind, for common ballast may shift by the rolling of a vessel. Moreover, no other ballast than water can be procured at sea to supply the daily waste.
(To be continued.)
HOW I BECAME A HERO. By G. P.
PART II. THE CHANGE.
Thursday came, and I stood at the entrance- gate to bid my new friends welcome to Beaumont. At the first sound of my voice Leslie Barrington uttered my name; and “How kind!“ — “How pleasant to be welcomed by a friend!“ — Mrs. Barrington laying great stress on the last word — followed immediately. While the trunks were being taken from the carriages, Leslie said:
“Walk me round, Terese.”
“This way, then,” she said.
She then, as people do with the blind, walked round the green in front, describing it to him, always using the word that sounded to me so sadly:
“See, see, dear Leslie, there on the right is the gate by which we entered — a handsome-looking iron gate; there is a low wall on each side of this gate with iron railings on the top. It joins the house, see, on one side of the gate, and it is met at the other angle by a high wall — the high wall opposite to us. How pretty it looks! — a vine, a Virginia creeper, and such a climbing rose! A high wall, just like the opposite one, on our left, too. I wonder why that side is bare of trees and plants! Close to the house there is a narrow doorway, a doorway in the wall — let us go through it.”
I opened the door, and she exclaimed:
“Oh, such a sight! Leslie, this is what you are supposed to know nothing about. There is a gable standing: how melancholy those exposed walls look, with their green and brown paper! The timbers in the roof are pretty, forming lines and triangles.”
We walked through the large square at the back of the house, which had been made tolerably free of rubbish for the convenience of the tenants, and we stood on the open down, with the skylark singing above us and busy insect life all around. Mr. Barrington enjoyed it greatly.