374 EXPLANATION OF THE PLATES. 



internal parts of the engines, whereby cles into the cylinder, thus, this ample 



they are rendered untrue, and a consider- lubrication actually improves the slides, 



able quantity of steam escapes past them valves, and other internal parts of the en- 



and is wasted. gines instead of injuring them, whereby 



a great saving in their wear and tear is 



effected. 



8. In injection engines, salt water, dirt, In the patent engines, nothing but dis- 

 sand, and other impurities pass through tilled water and oil pass through the 

 the air pumps and thereby render them air pumps, which instead of becoming 

 and their piston rods, &c., very rough and rough are thereby rendered more smooth 

 full of furrows ; in consequence whereof, and polished, and of course brass buckets, 

 great friction in working them and waste piston rods, and linings to the air pumps 

 of power is occasioned. are not necessary, as is the case in injec- 

 tion engines. 



9. In injection engines, a considerable In the patent engines, the air pump has 

 power is required to pump out the injec- only to pump out of the vacuum, the wa- 

 tion water; in engines of 450 horse power, ter resulting from the condensation of the 

 (like those on board the Great Western,) steam, which in a pair of engines of 450 

 2700 gallons of water per minute ha veto horse power is only about 50 gallons per 

 be pumped out of a vacuum, (reckoning minute ; the saving of the power, there- 

 six gallons per horse power per minute,) fore, required to pump out the 2700 gal- 

 and this requires as much power as the Ions per minute of injection water is so 

 pumping of that quantity of water out of much additional effective power gained 

 a well 30 or 32 feet deep. and applicable to the paddle wheels. 



10. In injection engines, in stormy wea- The patent engines, in the roughest 

 ther and heavy seas the condensing water weather and when the greatest power is 

 enters the condensers as rapidly when the required, preserve as perfect a vacuum, and 

 engines are going at a slow as when they consequently as great a power, as in fine 

 are going at a fast speed, and as it is impos- weather, and all the power required in 

 sible to regulate the quantity of injection injection engines to supply the proper 

 water according to the irregularity of the quantity of condensing water is super- 

 speed of the engines, great danger arises seded, and the engineer is relieved from 

 on the one hand of choking the condenser that onerous duty. 



and the air pump, and of even breaking 

 down the engines, by the admission of 

 too much water when they are going 

 slow, or on the other hand, of deducting 

 greatly from the power of the engines by 



