374 
EXPLANATION OF THE PLATES. 
internal parts of the engines, whereby 
they are rendered untrue, and a consider 
able quantity of steam escapes past them 
and is wasted. 
8. In injection engines, salt water, dirt, 
sand, and other impurities pass through 
the air pumps and thereby render them 
and their piston rods, &c., very rough and 
full of furrows; in consequence whereof, 
great friction in working them and waste 
of power is occasioned. 
9. In injection engines, a considerable 
power is required to pump out the injec 
tion water; in engines of 450 horse power, 
(like those on board the Great Western,) 
2700 gallons of water per minute have to 
be pumped out of a vacuum, (reckoning 
six gallons per horse power per minute,) 
and this requires as much power as the 
pumping of that quantity of water out of 
a well 30 or 32 feet deep. 
10. In injection engines, in stormy wea 
ther and heavy seas the condensing water 
enters the condensers as rapidly when the 
engines are going at a slow as when they 
are going at a fast speed, and as it is impos 
sible to regulate the quantity of injection 
water according to the irregularity of the 
speed of the engines, great danger arises 
on the one hand of choking the condenser 
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 
cles into the cylinder, thus, this ample 
lubrication actually improves the slides, 
valves, and other internal parts of the en 
gines instead of injuring them, whereby 
a great saving in their wear and tear is 
effected. 
In the patent engines, nothing but dis 
tilled water and oil pass through the 
air pumps, which instead of becoming 
rough are thereby rendered more smooth 
and polished, and of course brass buckets, 
piston rods, and linings to the ah pumps 
are not necessary, as is the case in injec 
tion engines. 
In the patent engines, the air pump has 
only to pump out of the vacuum, the wa 
ter resulting from the condensation of the 
steam, which in a pair of engines of 450 
horse power is only about 50 gallons per 
minute; the saving of the power, there 
fore, required to pump out the 2700 gal 
lons per minute of injection water is so 
much additional effective power gained 
and applicable to the paddle wheels. 
The patent engines, in the roughest 
weather and when the greatest power is 
required, preserve as perfect a vacuum, and 
consequently as great a power, as in fine 
weather, and all the power required in 
injection engines to supply the proper 
quantity of condensing water is super 
seded, and the engineer is relieved from 
that onerous duty.