14 APPENDIX. 



be anticipated, such as canvass would effect, it being sufficiently understood by commanders 

 who have the least acquaintance with steam vessels, that the sails are a disadvantage when 

 they give the lee-wheel too much depression. A single boiler may be at least eight feet wide 

 without any risk, with the ordinary quantity of water above the tubes ; indeed nearly twice this 

 width may be trusted safely, as instanced in front boilers containing four fire-places of 

 considerable size. A wash plate fitted into the middle of the after boiler, fore and aft, upon 

 the flues as high as the water line, would answer every purpose of preventing the water from 

 entirely leaving the wing flues, on taking a lurch : the same arrangement may be adopted in 

 a front boiler ; but it is not absolutely necessary, the water above the tubes having a greater 

 depth, generally, than that of the other boilers. 



25. Boilers for steam vessels of great or considerable power are necessarily constructed in 

 two, three, or more parts : these parts are best arranged when they are the entire length of the 

 boiler fore and aft, their ends forming the front and back of the whole : thus the longitudinal 

 boiler precludes the inconvenience liable to connecting pipes in the coal-boxes, and to the 

 heavy rolling of the vessel causing the water to recede from above the flues. Each boiler 

 can then be entirely distinct from its neighbour, having its own feed and blow off pipes, and 

 containing its own fire-places and flues ; the smoke and heated air arriving at the upper 

 surface of the boiler, to the chimney, before it mixes with that from the other boiler or 

 boilers. The base of the chimney in the case of three boilers, placed side by side, may be of 

 an elliptical or oblong, instead of cylindrical figure, covering the mouths of the flues, which 

 should each be furnished with a damper, fitted directly on the boiler, and quite distinct from 

 the funnel ; having a communication by levers with the engine-room in front of the boilers, 

 and thus being at all times under the control of those below. 



When a DAMPER is fitted in the chimney, it will inevitably be carried away with it in case 

 of accident, and the ship exposed to fire: a recent instance occurred in the 'Thames' Irish 

 steamer, in the Channel, where the vessel was nearly on fire from the sudden loss of the funnel 

 by a ship running on board her in the night. I have seen funnels carried away in harbours, 

 by getting athwart hawse of other vessels. Accidents are not uncommon at sea, particularly 

 when the funnels are of copper, which, decaying rapidly within the air casing, is less calculated 

 to resist a gale than iron. I have frequently been surprised that funnels stand so well as they 

 do ; preventer stays are often necessary : therefore, fitting dampers in the chimney should by 

 no means be adopted. 



To complete the arrangement, each steam pipe should have a COMMUNICATION VALVE ; or 

 a valve should be fitted on top of the steam chest of each boiler, where they join the common 

 steam pipe; so that either of the boilers may be employed, without at all depending on its 

 neighbour ; the safety valves, as usual, having one common waste steam pipe. The advantage 

 of this mode of construction is obvious, when it is understood that in a gale of wind, or in the 

 case of a ship of war cruising with a squadron by steam, not half the power can be 

 employed with effect j then one boiler or two can be dispensed with, according to necessity, 

 with a saving of fuel, almost in a ratio to the consumption of the boilers unemployed ; I say 

 almost, because a certain portion of heat will be lost by radiation, and by the absorption of the 

 contiguous boiler. In going head to wind the above advantages are most felt ; for the number 

 of revolutions at full speed, of sea-going steam vessels, varying from thirty to twenty-two 

 per minute in smooth water, within the limits of 80 and 200 horse power inclusive, and 

 when contending with a strong gale ahead, the speed being reduced to eight or nine 



