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part of the duty of the engineer, as they are quite superseded by no injection taking 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 Sirius 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 Meqcera 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 Eotterdam, belonging to the St. George Steam Packet Company.