512 
THEORY OF LOCOMOTIVE CARRIAGES. 
transition state of society, have great 
interest and importance, and which, 
having specially occupied the attention 
of a certain class of men eminent in 
science, seem to claim for thomselves 
a separate discussion. From this neces- 
sity resulted, last year, the Sub-Section, 
which has this year merged in Sec- 
tion E. 
At eleven o’clock the Hall of As- 
sembly was filled by Members of the 
Association, among whom we recog- 
nized some of the most distinguished 
of that class of individuals who, under 
the name of civil engineers, are work- 
ing a change in the face of society, 
more remarkable, and, perhaps, more 
durable, than any which history has to 
record of the legislator or the conquer- 
or — conquerors where victory is over 
space and time, and bloodless, and who 
achieve it, not by the increase of hu- 
man suffering, but by the increasing 
profitable employment of human la- 
bour. 
The discussions were opened by 
some observations of Professor Mose- 
ley on the theory of Locomotive 
Carriages. — It appeared to be the ob- 
ject of these remarks, to establish the 
importance of causing to enter into the 
discussion of the theory of locomotion 
on Piail-roads, the friction of the ma- 
chinery of the locomotive carriage it- 
self. This friction, the Professor stated 
to be composed of two distinct elements 
—one of which he termed the passive 
resistance of the machinery, being that 
which would oppose itself to a force 
applied to turn the wheels of the loco- 
motive carriage if it were lifted from 
the rail-road. This friction he stated 
to amount, in some cases, to 120lb. and 
in others, to 170 or 180lb. in the carri- 
ages employed on the Manchester rail- 
road. 
Besides this passive resistance of the 
engine itself, independent as it is of the 
load, the elevation of rail- road, the 
velocity, or any other cause \vhich 
effects the other conditions of locomo- 
tion, the Professor stated that there 
was a second element of the friction of 
the machinery, which was dependent 
upon, and proportional to the load, 
inasmuch as it was dependent upon, 
and proportional to, the traction, which, 
in its turn, was dependent upon, and 
proportional to the load. 
The friction of the machinery being 
thus composed of turn elements, one 
constant, and the other proportional to 
the load, the Professor stated that the 
third element of the resistance was the 
traction itself, being the friction of the 
train. The resistance being transferred, 
and operating upon one side of the 
piston, that which overcame it on the 
other side w-^as the pressure of the 
steam, which, supposing the vaporizing 
power of the engine to be constant, va- 
ried inversely as the velocity. More- 
over, w'hen the machine had acquiied 
its constant velocity, he stated that 
these two pressures must have become 
equal. These results and reasonings 
be stated not to be new, but not to be 
generally known: for the application 
of them to the theory of inclined 
planes, which followed, he claimed en- 
tire novelty. If (said the Professor) 
a locomotive carriage be made, with its 
train, to ascend an inclind plane the 
following modifications will be made 
in the resistance to the motion of the 
machine and train. The passive fric- 
tion of the machine will remain un- 
changed — the friction resulting from 
the traction wdll increase in the propor- 
tion in which the traction is increased, 
— the traction will be increased by the 
resolved portion of the gravity in the 
direction of the plane, and it wdll be 
diminished, in so far as the friction of 
the train is concerned, in a ratio pro- 
portional to the course of the elevation. 
This diminution of friction of the train, 
he stated, nevertheless, to be counter- 
balanced by the increased distance 
through which the w^hole mass is 
moved ; so that, on the w^hole, its effect 
was the same as though the whole had 
traversed a horizontal plane; so that 
on the whole, the traction of the train, 
arising from friction, and the friction 
of the machinery resulting from this 
cause, remained unaffected by the as- 
cent. Again, the increased traction 
from gravity in ascent, he stated to be 
compensated by the diminished traction 
in descent, or, if the angle be greater 
than that of repose, by the actual 
acceleration in descent. But there 
remains, said the Professor, another 
clement to be considered — namely, the 
friction of the machinery, which results 
from that increased traction produced 
by gravity in the ascent. This he stated 
to have no compensation in the descent. 
II 
ji 
i 
