LARDNER ON THE THEORY OF RAIL-ROADS. 
513 
by the ascent of the carriage the trac- 
tion upon it might be increased double 
the friction of its machinery would then 
be doubled; but, by the descent, the 
carriage and its train being equally ac- 
celerated, the friction resulting from 
traction would, indeed, be reduced to 
nothing, but it could assume no negative 
form compensating the friction of the 
machinery in the ascent : so that, on 
the whole, there was lost the whole 
increased friction of the machinery in 
the ascent, compensated by no corres- 
ponding diminution in the descent. 
These remarks the Professor stated to 
apply exclusively to the case of inclined 
planes having an elevation greater than 
the angle of repose. The loss of power 
in this case he stated tobe considerable, 
amounting, perhaps, to one-fifth of the 
traction, and, since an inclined plane 
will not unfrequently double or triple 
the traction, amounting in the whole to 
a considerable fraction of the force 
expended and the coal consumed. The 
great loss of power thus resulting from 
the increased friction of the machinery in 
an ascent not compensated in the subse- 
quent descent, the Professor stated to be 
an element neglected in the computations 
usually made on th^ expense of differ- 
ent lines of rail-road. 
Dr, Lardner stated his entire concur- 
rence in all that had fallen from Pro- 
fessor Moseley, and then proceeded to 
enter upon the discussion of a variety 
of facts of great interest and importance 
connected with the theory of rail-roads, 
to which having had his attention of 
late called by frequent examinations 
before committees of parliament, he 
had devoted much time. The traction 
resulting from friction on a horizontal 
plane, he stated to have been estimated 
differently by different engineers, at 
from 81b. to lllb. per ton ; from some 
. experiments of his own, made with 
much care, he concluded it to be about 
7|lb., by which sum the traction was 
increased by each additional ton of 
loading. He alluded to a variety of 
circumstances by which this fraction 
may be modified, and mentioned, in 
particular, the effect which wetting the 
rail appeared to have upon it — the car- 
riages, after a shower of rain, travelling 
with much greater speed and facility 
than before it ; and he suggested, that 
watering pots might, with great ad- 
vantage, be placed before a train of 
carriages, washing the rail continually 
for the wheels which were to follow it. 
The condition of the rail opposite to 
this, of its greatest freedom from fric- 
tion, was that in which it was covered 
with particles of earth, triturated stone 
or dust ; to try the effect of this condi- 
tion of the rail he had strewed sand on 
the surface of the rail, where it had an 
inclination above the angle of repose, 
and had found the friction of this sand 
sufficient to counteract the tendency of 
the train to descend by its gravity. It 
having appeared, from some of Dr, 
Lardner’s remarks that he considered 
the loss of force produced by the work- 
ing of a carriage over an inclined plane 
to result from the necessity of applying 
the break when the angle is greater 
than that of repose, and from no other 
theoretical cause, although practically 
there was a sacrifice in the working of 
the engine by reason of the superfluous 
stream thrown off in the descent. Pro- 
fessor Mosely inquired, whether in the 
event of the steam thus lost being by 
some means husbanded from the peri- 
od when the train commenced its des- 
cent, and the break not put on, he 
would consider any force to be lost in 
the whole transit of the carriage over 
the incline. The Doctor having de- 
clared that to be his view of the matter. 
Professor Mosely stated that he had not 
then fully understood the bearing of 
his remarks, or did not agree in them* 
The resistance to the motion of the 
carriage, he again stated to be compos- 
ed of a constant element, and an ele- 
ment varying in every case with the 
traction : — the constant element in 
working an incline, to be worked round 
the two sides of a triangle instead of 
the one side, which it would traverse 
if there were no incline; — and the 
other element, varying with the trac- 
tion, and dependent upon the friction 
of the machinery of the engine, to be 
greatly increased in the ascent of the 
plane, and to be evanescent in the des- 
cent ; thus presenting itself in the 
descent in no negative form, under 
which it might compensate the loss in 
the ascent. — The Section having been 
addressed by two of its members, whose 
names were unknown to us, one of 
whom stated the method of watering 
the rails to have been adopted with 
success on some of the tram-roads in 
Wales, the President rose and shortly 
