A Catechism of the Steam Engine

by C. E. John Bourne

A.--In some cases of collision, the funnel is carried away and lost overboard, and such cases are among the most difficult for which a remedy can be sought. If flame come out of the chimney when the funnel is knocked away, so as to incur the risk of setting the ship on fire, the uptake of the boiler must be covered over with an iron plate, or be sufficiently covered to prevent such injury. A temporary chimney must then be made of such materials as are on board the ship. If there are bricks and clay or lime on board, a square chimney may be built with them, or, if there be sheet iron plates on board, a square chimney may be constructed of them. In the absence of such materials, the awning stanchions may be set up round the chimney, and chain rove in through among them in the manner of wicker work, so as to make an iron wicker chimney, which may then be plastered outside with wet ashes mixed with clay, flour, or any other material that will give the ashes cohesion. War steamers should carry short spare funnels, which may easily be set up should the original funnel be shot away; and if a jet of steam be let into the chimney, a very short and small funnel will suffice for the purpose of draught.

MANAGEMENT OF MARINE ENGINES.

736. Q.--What are the most important of the points which suggest themselves to you in connection with the management of marine engines?

A.--The attendants upon engines should prepare themselves for any casualty that may arise, by considering possible cases of derangement, and deciding In what way they would act should certain accidents occur. The course to be pursued must have reference to particular engines, and no general rules can therefore be given; but every marine engineer should be prepared with the measures to be pursued in the emergencies in which he may be called upon to act, and where everything may depend upon his energy and decision.

737. Q.--What is the first point of a marine engineer's duty?

A.--The safe custody of the boiler. He must see that the feed is maintained, being neither too high nor too low, and that blowing out the supersalted water is practised sufficiently. The saltness of the water at every half hour should be entered in the log book, together with the pressure of steam, number of revolutions of the engine, and any other particulars which have to be recorded. The economical use of the fuel is another matter which should receive particular attention. If the coal is very small, it should be wetted before being put on the fire. Next to the safety of the boiler, the bearings of the engine are the most important consideration. These points, indeed, constitute the main parts of the duty of an engineer, supposing no accident to the machinery to have taken place.

738. Q.--If the eccentric catches or hoops were disabled, how would you work the valve?

A.--If the eccentric catches or hoops break or come off, and the damage cannot readily be repaired, the valve may be worked by attaching the end of the starting handle to any convenient part of the other engine, or to some part in connection with the connecting rod of the same engine. In side lever engines, with the starting bar hanging from the top of the diagonal stay, as is a very common arrangement, the valve might be wrought by leading a rope from the side lever of the other engine through blocks so as to give a horizontal pull to the hanging starting bar, and the bar could be brought back by a weight. Another plan would be, to lash a piece of wood to the cross tail butt of the damaged engine, so as to obtain a sufficient throw for working the valve, and then to lead a piece of wood or iron, from a suitable point in the piece of wood attached to the cross tail, to the starting handle, whereby the valve would receive its proper motion. In oscillating engines it is easy to give the required motion to the valve, by deriving it from the oscillation of the cylinder.

739. Q.--What would you do if a crank pin broke?

A.--If the crank pin breaks in a paddle vessel with two engines, the other engine must be made to work one wheel. In a screw vessel the same course may be pursued, provided the broken crank is not the one through which the force of the other engine is communicated to the screw. In such a case the vessel will be as much disabled as if she broke the screw shaft or screw.