382 REPORT—1883. 
care having to be taken beyond what is ordinarily given in casting gun- 
metal. 
It also possesses this very important advantage in the production 
of large castings, that it may be melted in an ordinary reverberatory 
furnace without injury to the metal; very careful analysis of this alloy 
«before and after passing through the reverberatory furnace showing that 
there is no appreciable alteration in its constituents. A bar of this 
metal cast in sand in the ordinary way, 1 inch square, placed on sup- 
ports 12 inches apart, requires upwards of 4,200 pounds to break it; and 
before breaking it will bend to about a right angle, and it will sustain 
from 1,700 to 1,800 lbs. before taking a permanent set. These results 
are in every respect fully up to those of the best rolled wrought iron, as 
some test bars of both, exhibited, will show: we have therefore in this a 
material which can be cast with facility into any intricate form, which it 
would not be possible to forge in iron, yet possessing all its strength, 
toughness, and hardness. This quality of manganese bronze is used for a 
variety of purposes, including spur bevel, and all kinds of toothed wheels, 
gearing, worms and worm wheels, framing, brackets, and all kinds of 
supports, and connections of machines, crank-pin brasses, the shells of 
main and other bearings of marine and other engines, axle-boxes and 
other parts of locomotive engines; and it has been found admirably 
adapted for statuary and art purposes generally, being much admired for 
its fine colour; but the latter quality is quite a matter of taste, and the 
members of the Association will be able to form their opinion thereon 
by examining the beautiful clock and ornaments, kindly lent by Messrs. 
Elkington & Co., made of the manganese bronze. The metal also seems 
to be peculiarly adapted for large bells. The advantages in this latter 
application are that bells cast from it possess the same, or greater, sono- 
rousness with a more mellow tone, and are at the same time so tough 
that they cannot by any means be cracked, like bells made of ordinary 
bell-metal, which is obliged to be made brittle in order to acquire the 
requisite sonorousness. The sound of a bell is also, to some extent, a 
matter of taste, and those who take an interest in this question may form 
an opinion as to the suitableness of the manganese bronze for this pur- 
pose by sounding the one exhibited. But the most important application, 
in a commercial point of view, is undoubtedly to that of steamship pro- 
pellers, to which it has been largely applied. 
Owing to the great strength of this metal, and its non-liability to 
corrosion, propellers of it can be made thinner than even those of steel, 
the surface is beautifully smooth, and when cast they are theoretically 
true to form, as, not having to pass through the annealing furnace, they 
do not become distorted, as is generally the case with steel. For these 
reasons the manganese bronze has a great advantage over steel. It has 
been proved conclusively by the logs of a number of steamships that have 
had their steel propellers replaced by manganese bronze blades that their 
speed has been increased, and the consumption of coal diminished, while 
the weight, vibration, and strain on the ship and machinery is consider- 
ably reduced. In addition to this, all these advantages are secured at a 
considerably less ultimate cost, taking it upon the average life of a vessel ; 
for although the first cost of a manganese bronze propeller, or a propeller 
with manganese bronze blades, is about double that of steel, it is inde- 
structible, whereas at the end of about every three years the steel blades 
become so pitted and corroded that their renewal is indispensable, which 
