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of the smoke-box or pass out through bhe netting above. TULs is but one of the many 
devices in use, varying in construction, but yet embodying the same general princi- 
ples. With bhe u Extended Front-end" the principle is different iu many particulars; 
the exhaust pipes are oarried higher, fche point of discharge being above tho netting, 
creating what may be perhaps fitly called a vacuum draft, instead of a direct or more 
forced draft (as in the ot her devices named), thus admitting of a larger area of netting 
and « ([uali/.ing the draft more perfectly than with the other arrangements, in which the 
point of discharge is below the netting and nearer the bottom of the boiler or flues. 
My experience has been that more complete combustion of smoke and gases is ob- 
tained by this device than by the "Diamond Stack" and the appliances used in con- 
nection with it. The question of brick arches, or deflectors as an aid to combustion, 
has also received a good deal of attention and discussion from many who have made 
careful experiments with them, but I believe there is a great difference of opinion in 
regard to their utility for that purpose. My own experience is, that I have got better 
results from their use as an aid to combustion, and also as a preventive of lire being 
thrown from the stacks. of locomotives than without them. While no doubt a large 
percentage of the destruction of forests along the lines of railways may be attributable 
to fires originating from sparks from stacks and ash-pans of locomotives, yet it is also 
a question whether, owing to the imperfect combustion, a large percentage is due 
also to the escape of noxious vapors and gases from locomotives. At the time this 
may be an unseen factor, yet I believe it is a very potent one, and one, too, that can 
be overcome only by more perfect appliances for effecting that result. The practice 
now is, largely, to increase the dimensions of the cylinders of locomotives to the 
maximum which boilers with our present standard gauge of road can be made to 
supply. This forcing process I presume will prevail as long as coal ean be furnished 
for fuel to locomotives as cheaply as it is at present on many of the large railroads of 
the country, and in view of the increased tonnage locomotives can haul under this 
system; for it is a process quite necessary in generating steam enough to supply 
cylinders, which are perhaps not always in proportion to the boiler-capacity, nor 
with the end in view of a more perfect combustion. 
In regard to the best appliances to prevent the evils complained of, I have en» 
deavored as far as possible to confine myself to my own experience in the matter. I do 
not think it is my province to commend any one or particular device for this pinpose, 
nor do I think that any one can, in view of the fact that the service on the railways 
of this country and its conditions are so varied. The great difference in the quality 
of the coal used on the different roads, and many other factors, all combine to make 
it difficult to recommend any one device that would he applicable to all; while the 
same general principles might apply if modified to meet the requirements of differ- 
ent kinds of service and conditions. But from my own experience I believe that we 
are obtaining, and shall obtain, better results from the use of the "Extended Front- 
end," and its appliance, in the way of combustion and less liability to fire, than from 
the use of the " Diamond Stack" and its appliances. I believe also, if the importance 
of the matter should be properly presented to the managers of railways of this coun- 
try, and a reasonable amount of discretion is allowed to officials.in charge of the 
motive power of our railways to make a system of careful and intelligent experiments, 
tho best results will be obtained. 
Very truly yours, 
G. W. TILTON, 
Superintendent Motive Power and Machinery. 
