; 
378 REPORT— 1883. 
is no doubt greatly due to the fact that Messrs. Adamson and Co. make 
it a rule to test strips from every plate put into the boilers, having 
special machines of their own design for testing the tensile strength of 
the plates. The tunnel is lighted during construction by electric arc 
lights. The ventilation is at present secured by air-compressors, by 
bratticing, and by the staple-shafts connecting the tunnel and heading, 
but it is intended to erect permanent machinery for the mechanical venti- 
lation of the tunnel, through which trains will run at intervals of a few 
minutes only. [ Note.—The headings were successfully connected January 
17, 1884.] 
On Manganese Bronze. 
By P. M. Parsons, M.Jnst.C.k. 
[A communication ordered by the General Committee to be printed in extenso among 
the Reports. | 
BErForE entering on the immediate subject of this paper, I propose to 
give a brief description of what has previously been done in the same 
direction, and to review the theoretical considerations which have led to 
the production of manganese bronze. 
Many samples of bronze made by the ancients have been found to 
contain a small percentage of iron, but, as far as I am aware, no traces 
of manganese have ever been discovered; it is not unlikely that the 
ancients knew that the addition of iron to bronze would increase its 
hardness, and introduced it with that view. In more recent times the 
combination of iron with the brass alloys seems to have engaged 
the attention of inventors considerably, and a few have also introduced 
manganese by reducing the black oxide of manganese and combining it 
with the copper, but none of these alloys appear to have shown sufficient 
advantages to lead to their permanent adoption. 
Among the earliest of these inventors was James Kier, who, as far 
back as the year 1779, proposed an alloy of ten parts of iron with 100 of 
copper and 75 of zinc. Alloys of a similar character to this, but con- 
taining less iron and different proportions of copper and zinc, were sub- 
sequently introduced under the name of stereo-metal and aitch-metal, and 
Sir John Anderson, late Superintendent of the Royal Gun Factories, and 
Inspector of Machinery to the War Department, carried out a number of 
experiments with similar alloys, and with some good results, but no 
practical applications of any of them appear to have been made. The 
addition of iron unquestionably increased the strength and hardness of 
these alloys, but the experiments I have made show that they acquire 
these qualities at the expense of ductility and toughness, and it is pro- 
bably on this account that they have not come into general use. Besides 
these, various other inventors have proposed to combine iron with the 
brass alloys, but only Mr. Alexander Parkes, and the late Mr. J. D. 
Morries Stirling, both eminent metallurgists, proposed the use of man- 
ganese and appear to have carried their ideas into practice. 
Mr. Parkes’s inventions consisted in combining manganese with copper, 
and using this alloy instead of ordinary copper with zinc, to form im- 
proved alloys of brass, yellow metal, &c., of which to make sheathing, rods, 
wire, nails, tubes, &c. Mr. Everitt, of Birmingham, has also lately 
