obtained by manholes, Figs. 48 and 50, the latter being the type fitted on bulkheads, etc., and the former to the double-bottom compartments. The means of access to every compartment of a ship is given in the book of watertight compartments supplied, of which a specimen page is given at the end of Chapter IX.

It is laid down that every accessible part of the outer and inner bottom and framing is to be inspected once a quarter by the engineer officer and the carpenter, and any defects discovered are to be made good. In the event of dampness, the steel must be thoroughly dried and all traces of rust removed before applying the paint. Well-slacked lime is to be used in places from which water cannot be removed.

Every three years (annually in the case of destroyers and ships whose plating does not exceed in.) a complete survey is made by the dockyard officers.

Pipes at the lower parts of a ship should preferably be of galvanized iron, and not copper or lead. If, however, copper or lead pipes have to be used, it is necessary that they be well painted, covered with canvas, painted to make quite waterproof. In way of metal valves zinc protectors are fitted to assist in preventing corrosion.

The inner bottom plating under engines and boilers is specially liable to corrosion, especially the upper surface, due apparently to the fretting action of the ashes and hot water. These parts should be frequently examined, and where rust is found to be forming, or where the paint is abraded, the surface should be thoroughly scaled, cleaned, and dried, and coated with three coats of red-lead paint.

Cement. The cementing carried out in recent ships is of far less extent than that formerly adopted. The double bottom, which under ordinary circumstances will not contain water, is not cemented at all except in those spaces used for reserve feed water, where the bottom is coated with hard cement 1 to 2 in. thick. Before and abaft double bottom, just sufficient cement is used so that water will not obtain a lodgment anywhere, but will readily flow to the pump suctions. In parts, as at the extreme ends of the ship, where a considerable amount of cement is necessary, the cement is mixed with coke to keep the weight as small as possible. Cement may even be detrimental, supposing it to get cracked through any cause, as then water will get down to the plating, and corrosion may go on unnoticed.

The insides of fresh-water tanks are coated with "Rosbonite." In living spaces, etc., corrosion and discomfort is caused by the sweating of steel work, owing to the condensation of moisture from the air. In such spaces the under side of decks, bulkheads, etc., are painted with one coat of red-lead and then covered with fine cork and painted white. The cork does not cool so quickly as the steel, and so condensation does not take place so readily. This application is termed cork cementing.

(A very complete discussion of rusting, corrosion, and fouling in given in Professor Lewes's "Service Chemistry." See also a paper by Mr. Holzapfel, I.N.A., 1904.)

CHAPTER XII.

COALING.

THE rapid coaling of war vessels is a matter of considerable importance, and the present chapter is devoted to a brief consideration of the methods adopted for coaling in some recent large ships of the British Navy. The use of liquid fuel is still in the experimental stage; if it could be adopted, the getting on board and the storage would be a matter quite simple in comparison with what is necessary in the case of coal.

The subject of coaling divides naturally into three parts, viz.

1. coaling ship, i.e. getting the coal on board from lighters, etc.; 2. getting the coal down into the several bunkers; and 3. getting coal from the bunkers to stokeholds. The two latter are specially difficult in war-ships, because of the large number of bunkers caused by the extensive system of watertight subdivision (see Figs. 52 and 53), and also by the presence of the armoured decks, which it is undesirable to pierce more than is absolutely necessary.

1. Coaling Ship.-Figs. 112 and 112A show the general

arrangements adopted in a large cruiser. These arrangements would, of course, be supplemented when coaling from a ship in which derricks, transporters, etc.,

BOAT

WATER LINE.

DERRICK.

WINCH

/НАТСИ

FIG. 112A.

are fitted for dealing with the coal.

There are two steam coal winches, one on each side of the upper deck, each having a central barrel and two side warping barrels. The coal is got on board by a Temperley transporter (two in some ships), which can be suspended either from the derrick on the foremast or from the main derrick on the mainmast. This transporter is 55 ft. long, and is fixed in position by means of guys. It has to be used in a slanting

direction, so that the carrier will travel down by gravity when the coal-bags are empty. The transporter consists of an I beam, with a sheave on the upper end plumbing the upper deck; the lower end can be arranged to plumb the hold of the lighter.

The beam is provided with stops about 5 ft. apart, any one of which may be used to fix the load when it is desired to raise or lower. The lower end of the beam is fitted with a stop. The carrier itself runs on four rollers on the lower flange of the beam, and is composed of two side plates containing a number of cams. The purchase passes over a sheave on the carrier, and at its lower end has a heavy ball attached. Take the instant when the load is being lifted as Fig. 113. The double cam at the top is caught in the stop and the carrier is fixed. A further lift of the load, however, lifts up the pawl lever and catches the ball in the suspender hook as Fig. 114, and the weight is taken by the carrier. This movement of the levers, however, releases the double cam at the top away from the stop, and the whole carrier is then free to be hauled up the beam by hauling on the purchase. In order to fix the carrier to lower the load, it is hauled just past the desired stop as Figs. 115 and 116. The rope is then slightly slackened, and the toggle catches and turns the cam into the stop as Fig. 117. In this movement of the cam the carrier gets locked, and the ball gets released from the suspender hook and the weight

is free to be lowered as Fig. 113. When the empty coal-bags are lifted, the ball gets locked again by the suspender hook, and the carrier is loosened from the stop and is free to descend to the bottom of the beam by gravity. It will be noticed that a continuous motion past the stops is possible either up or down. If when going down the carrier is stopped just below the stop, then

taken up just past it and the motion again reversed, the toggle shown so acts as to turn the cam into the stop.

The largest of these transporters can deal with 20 to 30 cwt. of coal at a time. There is only one rope to deal with, and the various operations are entirely under the control of the man working the coal winch.

Besides the above, portable derricks 20 ft. long are fitted at the gangway ports, with coaling platforms (9 ft. 6 in. x 3 ft. 0 in.)

K