'I'he engine, as now completed, is a handsome piece of well finished accurate workmanship, and performs its part admirably. The young man who made all the principal parts of the engine is a self-taught mechanic, and merits the highest praise for the ingenuity, ele gance, and perfect workmanship which he has dis played upon it.
.Hccount of Mr. G. Gurney's Tube Boiler.
Various attempts have been made to construct boilers with tubes, but practical difficulties occurred which the ablest engineers sought in vain to remove. These difficulties arise from the water being carried off along with the steam, which left the containing vessel dry, oxidated the metal, and produced hy drogen, the heat of which destroyed the packings of the joints in the pipes and the working cylinder;— from the deposition of earthy concretions in the tubes, —and from the destruction of the joints by the sudden and unequal expansion of the metal composing the boiler.
Mr. Gurney's boiler is constructed with the view of obviating this objection. It is shown in Plate DIX, Fig. 14 and 15, Fig. 14 being a section, and Fig. 15 a front elevation of the boiler. A section of one of the tubes is shown in Fig. 14 surrounding the flame. Each end of every tube opens into two cylindrical chambers c c, and these chambers communicate by pipes with the vertical chambers a a, which receive the steam and water generated in the pipes. Here the steam and water are separated, the steam rising to the top, and the water falling to the bottom. Hence these chambers are called separators. These separators are united with the top of a tube b, in the centre of which the safety-valve is placed. The injection pipe of the forcing pump is inserted into either of these cham bers, d is a small well to receive any extraneous mat ter which may pass into the boiler, e e are the guage cocks for steam and water, the lower cock being the water level of the boiler. The fire-door is shown at f. Fig. 15 and 17 and 13, show the manner in which the tubes are fixed to the chamber c.
'I'he incrustation of salt and its corrosive action on the tubes appeared at first hostile to the use of the boiler at sea ; but Mr. Gurney has removed this ob jection by condensing the high pressure steam instead of blowing it off, and returning the water thus pro cured by means of a forcing pump into the boiler, so that by beginning with pure rain or distilled water, steam is continually generated without any great ex penditure of fresh water, as the steam from the engine is not only condensed, but also a part of this procured from the fresh water which is successively employed in condensing it, and which without loss of power in a steam vessel can be led from the water thrown up by the paddle wheels to a cistern for the purpose.
The following is the condenser employed by Mr. Gurney.
Description of Mr. Gurney's Condenser.
Mr. Gurney's Condenser is shown in Plate DIX) Fig. 19, 20, where a is a bent pipe joining the eduction pipe of the engine to the cone I of the condenser, which is a cylindrical vessel 31 feet long, and 7 inches diameter inside, for a 10 horse engine. Within this cylinder 40 copper tubes five-eighths of an inch in diam eter, are arranged in circles, and are inserted in plates at each end by steam tight joints as shown in Fig. 20. The nozle c is connected with a cold water pump which discharges about two gallons per minute for every horse power. In steam boats this is not necessary, as the water can be procured from the paddles. This water will rise in the cylinder so as to surround the tubes until it is ejected from the nozle d, from which it may return to the well or cistern. The steam which passes from the engine into the tubes is condensed be fore it reaches the lower cone e and falls into the close chamber below, from which it is carried by the suc tion pipe g to the injection pump of the boiler. When there is too little water in this chamber the ball of the cock falls and admits the proper quantity from the cylinder through the tube i. By the tube k air or va pour may he drawn out. Captain Ross, who saw this condenser in operation, is of opinion that it makes Mr. Gurney's boiler quite perfect for naval purposes.
Having thus described the most important im provements on the Steam Engine, we shall now give an account of some miscellaneous contrivances con nected with it.