in cleaning the grate-bars, that they do not get so 
much of it out as to bring the hot coals in contact with 
the bars and melt them down, and being compelled 
to use this inferior coal has made the consumption 
appear more than it really should be. 
The best coal could not be used in our locomotives 
with any certainty of success, until water grate-bars 
were substituted for cast iron; in fact, it was looked 
upon as a bad article for the purpose, because it would 
melt the cast iron grate-bars; but the water grates have 
shown that it is far preferable, as it not only takes less 
of it to perform a trip, but there is less required on the 
grate at a time, and the fire being thinner, a larger 
exhaust can be used, and consequently a much milder 
draft is produced; no fire is thrown from the chimney, 
and the increased area of the exhaust relieves the back 
pressure on the pistons, and thereby increases the 
power of the engine. 
In using the best anthracite coal in our passenger 
engines fitted with water-grates, I have seen the fire 
run down so low, when near the ends of the road, that 
a portion of the grate bars would be bare. And I 
have no hesitation in saying, that, with a properly 
constructed boiler, fitted with water- grates, and the use 
of good anthracite coal, all classes of locomotives, both 
passenger and freight, can be used with as much 
reliance as to their performances, both as to speed and 
power, as engines burning wood or any other fuel; 
and that a more uniform pressure of steam can be 
maintained on them, than any wood-burning pas- 
senger or freight engines that have been on our 
road for the past eleven years. It is, however, a 
matter of experiment with us now, to know what is 
the best material for a firebox, and the proper shape 
to put it in for service with anthracite coal. In the 
fireboxes of Winans’ engines, having a grate seven 
and a half feet long, and three and a half feet wide, 
with vertical side-sheets, we have been using copper, 
three-eighths of an inch thick; this, however, would 
not last more than about eighteen months, running 
about 25,373 miles, when the boilers had the entire 
back end of the firebox open, with two upper and one 
lower door to close when in use, and cast iron grate- 
bars. 
In this kind of a firebox, the side-sheets would be 
worn down in places to not more than a sixteenth of 
an inch thick; and in others, it would retain nearly 
its original thickness, but from what cause I am not 
able to say; but probably from mechanical action, as 
the thin places are generally found about where the 
coal would strike the side-sheets when thrown in with 
34 BULLETIN 252: 
a shovel. To remedy this wearing away of the side- 
sheets, I put in a harder material, iron; but it does not 
last so long as copper placed in a vertical position, 
as it appears to become very much overheated, and 
cracks vertically, showing a crystalline fracture, 
which, I have no doubt, is caused by the absence of 
water on the opposite side of the sheet from the fire. 
The steam generated on the side next to the water 
(in consequence of the sluggishness of the circulation, 
if any, in this part of the boiler), remains there in 
contact with it, and as it will not take up heat with as 
much facility as water, allows the iron to become too 
much overheated, and the first strain that comes upon 
it in the way of unequal expansion or contraction, 
causes it to crack; but copper being a more ductile 
material, is not affected in the same way, but becomes 
softer by the frequent heating and cooling, and there- 
fore appears to be the best material of the two, for 
this kind of firebox. 
I closed up one-half the open end firebox by putting 
a water back that took up one-quarter of the opening 
on each side of the firebox, leaving one-half the area 
of the end open from top to bottom; the lower half of 
the opening was closed by a grate door, which serves 
to admit air to the coal in that part of the furnace that 
would not be supplied with air if a solid door was 
used, and also for the purpose of inserting a slice-bar 
to break up the cinder on the grate. The upper half 
of the door is used for firing, and consists of two plates 
of cast iron, the inner one about two inches from the 
outer, leaving a space between, that was supplied 
with air through holes bored or cast in the outside 
plate; which air protects the inner plate to some ex- 
tent from the heat, and also supplies air to ignite the 
gases, and not to allow them to pass from the furnace 
unconsumed. 
‘This arrangement of doors increases the durability 
of the side-sheets, and engines whose boilers have 
been thus fitted, have run an average of 29,391 miles 
before the sheets required replacing. 
To introduce the water-grates, I was compelled to 
close the back end of the firebox, leaving an oval 
door for firing, the same as in the ordinary wood- 
burning boilers, but with a number of small holes in 
the inner plate of the door, and larger in the outer; 
and in some of the boilers, I have put hollow stay 
bolts, with an opening about one-quarter inch in 
diameter, in the back end of the fire-box. The side- 
sheets in the first boiler fitted with water-grates and 
closed back end, run 39,254 miles; and as this is the 
only one that wants the side-sheets renewed, I have no 
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