376 EXPLANATION OF THE PLATES. 



Fifth, as the internal parts of the engines are kept so much longer in repair owing 

 to the causes above mentioned, the perpetual expense and time required in repairing 

 such parts is greatly diminished; indeed there is no doubt but the slides, valves, pistons, 

 and all the internal parts of the engines are in much finer condition after having been 

 in operation for years, than they are the first day they are set to work. The 

 circumstance of salt being carried over with the steam into the cylinders (when salt 

 water is used in the boilers) is unquestionable, as well as that it is the cause of the 

 valves and other internal parts of the engines becoming so soon in bad condition, 

 whereby a great waste of steam takes place even long before they become so very 

 much worn as to render it indispensably necessary to give them a thorough repair. 



The regulation of injection water, and of the water to supply the boilers, forms no 

 part of the duty of the engineer, as they are quite superseded by no injection taking 

 place, and the boilers being self-supplied with undeviating accuracy. 



It may also be observed, that the comparative advantages of the patent engines do 

 not appear to be so great on the first starting of new engines, or even during the 

 first month or two, as the boilers and machinery of injection engines, are then as 

 clean and in as good order as those of the patent engines ; but afterwards, when the 

 boilers of the former become thickly coated with scale, the internal parts of the 

 engines are worn and galled, while those of the latter are actually improved, and the 

 comparison should then be made. 



Lastly, it is certain that a vessel with the patent engines of 300 horse power, 

 will effect an increase of economy and advantage of 2500 or 3000 per annum 

 over a vessel having injection engines of that power, and consequently the former 

 will realize so much greater a profit." 



The following engines are now in operation with the improvements applied to them: 



The Sinus steam ship with a pair of engines of 320 horses' power, both included, 

 on the station from London to New York, being the first steam vessel that performed 

 that voyage across the Atlantic and back. This vessel belongs to the St. George 

 Steam Packet Company, and is chartered by the British and American Steam Navi- 

 gation Company. 



The Megcera steam ship with a pair of engines of 140 horses' power, stationed 

 in the Mediterranean, and built by the Lords Commissioners of the Admiralty 

 for her Majesty's navy. Engravings of her engines are given in this work, Plates 

 XLIX., L. 



The Hercules steam vessel with a pair of engines of 180 horses' power, stationed 

 between Glasgow, Dublin, and Cork, belonging to the St. George Steam Packet Com- 

 pany. 



The Sea-horse steam vessel with a pair of engines of 260 horses' power, stationed 

 between Hull and Rotterdam, belonging to the St. George Steam Packet Company. 



