62 ON THE COMPARATIVE ECONOMY LIKELY TO RESULT 
sheaves, drums, and other necessary accom- 
paiiiments. The total annual expense of 
maintaining the moving power was estimated 
at 42,000^., and of this about 18,000/. was 
appropriated to the wear and tear of ropes, 
sheaves, &c. &c. 'J'hus it appears that the 
method of transmitting the power of the sta- 
tionary engines to the trains by ropes would 
absorb about 20 per cent, of tlie invested ca- 
pital, and their maintenance would consume 
about 43 per cent, of the annual expenditure. 
Another source of comparative economy 
xvould obviously be the diminished number of 
stationary engines. In the estimate already 
referred to, it was calculated that the distance 
of 30 miles should be divided into 17 stations, 
with two 40-horse engines at each station ; 
besides these, there would have been two en- 
gines at the bottom of each inclined plane, one 
at the tunnel, two at the top of the planes, 
and one at the Manchester end, making in all 
42 stationary engines to work a line of 30 
miles. Now, according to the estimate of the 
patentee of the Pneumatic Railway, from 
three to six stations would be sufficient be- 
tween Manchester and Liverpool, and the 
whole line would be worked by from six to 
twelve stearn-engines. Putting aside, there- 
fore, the saving of power which woirld arise 
from the substitution of suction in the tunnel 
for ropes, and supposing the amount of stati- 
onary power in both cases to be the same, 
it will be evident that a material saving would 
arise from the circumstance of that amount of 
power being derived from so much less a num- 
ber of engines — the number of enginemen, as- 
sistants, &c., besides the interest on capital, 
being considerably less. 
Some notion of the economy of power likely 
to arise from superseding the use of ropes 
may be collected from the result of experi- 
ments made by Messrs. Stephenson and 
Locke, on the resistance arising from the 
friction of ropes. They found that a load 
of 52 tons, drawn by stationary engines worked 
by ropes, through mile and half stages, offer- 
ed a total resistance amounting to 11,56 lbs. ; 
of this 582 lbs. arose from the friction of the 
load, and 5741bs. from the friction of the 
ropes. In the case of the Pneumatic Rail- 
way, the friction of the rope is replaced by the 
friction ofthe air-pumps and of the impelling 
apparatus; and it will be evident that the 
latter, compared with the former, must be al- 
most insignificant. Hence the power wasted 
m its transmission from the stationary engines 
to the load, which in one case amounts to 50 
per cent, of the whole moving power of the 
engine, in the other is of comparatively tri- 
fling amount. 
Slopes on railways will alway be objection- 
able, w'hatever power be used ; for even the 
most gentle ascent will increase the resistance 
of the load in an enormous proportion. The 
difficulties, however, which they present are 
materially less when the line is worked by 
stationary than by locomotive-engines, and 
w'ould be still further diminished by supersed- 
ing the rope ; the resistance arising from the 
rope being always greater on inclined-planes 
than on the level , owing to its increased thick- 
ness and consequent weight. A load which 
requires a 4-^-inch rope for the level requires 
a 5^-inch rope upon a slope of 1 in 100. The 
weights of equal lengths of these ropes would 
be iri the proportion of about 2 to 3, the slope 
requiring one-half more weight of rope than 
the level. Resides this, the moving power on 
a slope, in addition to the ordinary friction 
which it has to overcome on the level, has 
likewise to draw up the v/eight ofthe rope— a 
resistance which will be increased in proper- 
lion to the acclivity of the slope. 
The disadvantages produced by slopes 
when locomotive-engines are used are still 
more formidable. The same engine which 
is fitted to work upon the level is altogether 
inadequate for the slopes ; the consequence 
of which is, either, that the locomotive is 
strained beyond its power by working up the 
slopes and rapidly destroyed, or that the en- 
gines must be more powerful than is requisite 
for the common level of the road, and thus 
power and expense wasted ; or finally, that an 
auxiliary engine must be kept constantly 
ready at the foot of each slope, with its fire 
lighted and its steam up, ready to help up the 
trains as they arrive. Unless the trains be 
almost incessant ('which even on the most 
frequented railroad they never can be), this 
last expedient, which is the one adopted on 
the Manchester line, is attended with great 
waste of power and expense. Stationary 
engines worked on the pneumatic principle 
w’ould effectually remove all these difficulties 
and objections. 
The weight of the trains which could be 
drawn upon the Pneumatic Railway, and the 
speed of the motion imparted to them would 
entirely depend upon the power of the stati- 
onary engines. As the friction or other resis- 
tance does not increase with the velocity, the 
same absolute expenditure of power would 
draw the same load at whatever speed. 'I'he 
high speed attained by locomotive engines has 
been attended with great expense, but this has 
not arisen from the increased expenditure of 
power. It has been caused by the wear of 
the engines themselves, consequent on their 
rapid motion on the road, and by the necessi- 
ty of sustaining a fierce temperature, in the 
fire-place, in order to be able, within the 
small compass of these engines, to generate 
steam with sufficient rapidity to attain the 
necessary rate of motion. As the magnitude 
of the stationary engines would not be limited, 
and as they would not be subject to the injuri- 
ous effects of motion on the road, steam could 
be produced in sufficient quantity for the at- 
tainment of any required speed, without 
increasing its cost or in any way impairing' 
the machinery. 
One of the obstacles to the attainment of 
great speed by stationary engines worked by- 
ropes, is the delay produced in transferring 
the trains from engine to engine, and from 
station to station. The momentum imparted to 
them is lost at each change, and these changes 
occur every mile and a half, so that the train 
has scarcely attained its requisite speed when 
its motion must again be checked in order to 
hand it over to another engine. This difficulty 
is removed by the pneumatic system ; there 
being no rope to be detached and attached , the 
