MAGAZINE OF SCIENCE AND ART, 
79 
It is a fact, however, that this law is not found to 
apply to weights moving upon a railway, for, in this 
case, mechanical science has introduced a new and 
grand principle, heinc nothing less than a means of ex¬ 
tinguishing almost the whole effect of friction—that 
great natural opposer of all motion. 
From a series of experiments on the performance of 
locomotive engines on the Liverpool and Manchester 
railway, made by the Chevalier de Tambour, in which 
the value of every force which operates cither to effect 
or to retard motion has been deduced from actual ex 
periment, the following results were obtained :— 
Weight in Tons. Velocity in Miles per hour. 
25 . 40.07 
50 . 31-34 
75 . 25.74 
100 . 21.83 
125 . 18.96 
150 .. 16.75 
166 . 15.59 
One of the most important results of these experi¬ 
ments is that the velocity on a railway is not, as is 
usually supposed, in the inverse ratio of the weight; 
and if we examine the velocities here given as cor¬ 
responding to different weights moved, we shall find 
that the most useful effect produced is when the weight 
is the greatest. 
For instance—Taking the extremes in the table, we 
find 25 tons conveyed at tbe velocity of 40.07 miles in 
an hour, equal to 1 ton conveyed 1,002 miles ; whereas 
166 tons, at 15.59 miles an hour, aie equivalent to 1 
ton conveyed 2,588 miles. Hence the useful effect 
where a load of 25 tons is carried on a railway, is to 
the useful effect with a load of 166 tons in the ratio of 
1,002 to 2,588, or as 1 to 21. Hence we see that the 
most useful effect is produced by conveying the greatest 
possible weight that the engine is capable of, and that 
any less weight is carried at a sacrifice of useful effect. 
An ordinary passenger train may be estimated to 
weigh about 50 tons, which, at the ordinary railway 
speed of 31 miles an hour, gives an effect equal to 1 ton 
conveyed 1,550 miles But if the weight of the train 
he reduced to 25 tons, the speed being the same, the 
effect produced is equal to 1 ton conveyed 775 miles 
only. Now, in cases of moderate traffic, it will often 
happen that the weight of the load carried is les«s than 
25 tons, while the power of the engine may be equal to 
the conveyance of a load of 150 tons. The loss of effect 
in this case is apparent, for the engine must always be 
kept in readiness, whatever may be the number of pas¬ 
sengers or the quantity of goods to be conveyed, This 
evil is a constant one and cannot be remedied. In 
bringing into view so prominently the value of steam 
as a moving forco upon railways, it is too common to 
overlook tlie fact that the great weight of locomotive 
engines is a positive evil. It is so because they have 
to carry this weight constantly, and because their 
weight does more harm to the road than anything else, 
and that a railway must necessarily be made much 
stronger and more costly on account of it. 
Again, it is well known that in order that the same 
locomotive may travel, without any assistant power, 
from one end of the line to the other, the steepest incli¬ 
nation must be taken as the guage of the power of the 
engine, and that the weight of an engine must be in¬ 
creased, in a certain ratio, to tbe power it is intended to 
exert. 
The weight of engines and tenders varies considerably 
on different railways, according to the gradients. On a 
line with variable gradients and with a narrow guage, 
the weight varies from 15 to 20 tons ; and on the broad 
guage from 25 to 35 tons. Here, then, we have a dead 
and unprofitable weight to be moved, equal in the first 
case, wnen the whole weight of the train does not exceed 
50 tons, to no less than one-third of the gross weight to 
be conveyed, and tho increased weight of the engine and 
tender will add very materially to the weight and 
strength of the rails, which must of course be provided 
of a strength sufficient to support the engine intended to 
be used. ^ _ 
It must be borne in mind that the gross weight of the 
goods to be conveyed on a railway does not affect the 
strength of the rails, as the load, independent of tbe 
engine, is distributed in a train of carriages over a con¬ 
siderable length, without materially increasing the 
pressure on tho rails at any one point. But an in¬ 
creased weight of engine must evidently require an 
increased strength in the permanent way over which it 
has to pass, because in the engine the weight can only 
he distributed upon four or, at most, upon six wheels. 
Another consequence of using a large and heavy 
engine is that a much greater supply of water and fuel 
will be required, and the quantity of these regulates 
the size and weight of the tender employed to carry 
them. 
Since it is the steepest piano or incline on a line of 
railway which determines the power and weight of the 
engine! it is found in practice that unless the inclina¬ 
tions are of very great length, little advantage can be 
taken of the diminished resistance in going down them, 
as regards the expenditure of steam ; for although it is 
not wanted to an equal extent, as in ascending the in¬ 
clines, yet a great portion of steam is wasted by blowing 
oft* at the safety valve. Again, the consumption of 
steam will be in proportion to the power which it is 
necessary for the engine to exert; but, on account of 
the limited area of the boiler of an ordinary narrow 
guage locomotive engine, there seldom exists more 
steam than is immediately required, for the supply and 
demand are in general so nearly balanced, that the one 
can hardly be said to exceed the other. 
If the line be greatly undulating, and an average 
velocity be not maintained, it will of course be neces¬ 
sary to* increase tbe speed on tbe descending planes, in 
order to make up for the. loss of speed on tbe ascending 
ones, and when compelled to proceed at very high ve¬ 
locities, the working parts of an engine are subject to 
considerable injury. The pistons might to travel with 
great equality of speed, because any sudden changes in 
the rapidity of the stroke give rise' to concussions which 
are highly detrimental to the engine, and occasion the 
slides to become leaky, causing a great waste of steam. 
All these circumstances entail the necessity of con¬ 
stant and vigilant attention on the part of the persons 
entrusted with the care of the engines. A steam rail¬ 
way requires not only rails and sleepers of great 
strength and durability, but also turn-tables, switches, 
points, signals, expensive engines, tenders and carriages, 
together with costly workshops, tools, aud a host of 
skilled workmen and mechanics, all of which, in Aus¬ 
tralia, preclude economy. But tho cost of working and 
maintaining a railway by steam power does not consist 
•solely of the expense of engine power. There are also 
other expenses which remain constant, and which are 
termed fixed expenses. These expenses vary in Eng¬ 
land from £250 to £300 per mile, and they embrace 
every charge except that appertaining to tho engines, 
the carriages and their attendants—as the salaries of 
the resident engineer, the secretary and the superinten¬ 
dents, the wages of station keepers, turnplate and signal 
men, the expenses attending the supply of water and 
fuel at the stations, the repairs of buildings, bridges, 
cnlverts and viaducts, and the keeping in repair the 
permanent way. 
It is difficult to fix these expenses, with any degree 
of certainty, in Australia, or the cost of locomotive en¬ 
gine power. In England this cost varies from Is. 2d. 
to 2s. 4d. per mile per train, at an average speed of 31 
miles an hour. The latter sum, at 80 miles per day 
for 313 working days, amounts to £3,077 per annum. 
It is believed that, taking into consideration thejrighor 
rates of wages in Australia, the cost of locomotive en¬ 
gine power may be estimated at 3s. Cd. per mile per 
train. The cost, therefore, of a locomotive engine 
travelling 80 miles per day for S13 working days, will 
amount to £4,382 per annum. 
In England passenger trains frequently travel at a 
