ADDRESS. 15 
raising a given amount of iron to the temperature of fusion, he points out 
that the same object would probably be more economically attained by 
the use of a magneto-electric machine, which would allow the heat to be 
provided by the expenditure of mechanical force, developed in the first 
instance by the expenditure of heat; and he indicates the possibility of 
arranging machinery to produce electric currents which shall evolve one- 
tenth of the total heat due to the combustion of the coal used, so that 
5,000 grains of coal applied through that agency would suffice for the 
fusion of one pound of iron. The successful practical realisation of Joule’s 
predictions in regard to the application of electric currents, thus developed, 
to the welding of iron and steel, and to analogous operations, through 
the agency of the efficient machines devised by Professor Elihu Themson, 
was demonstrated to the members of the Association by Professor Ayrton 
at Bath two years ago, and was shown upon a larger scale to visitors at 
the Paris Exhibition last year, and recently to highly interested audiences 
in London by our late President, Sir Frederick Bramwell. The latter 
demonstrated that the production of iron-welds by means of the Thomson- 
machines was accomplished nearly twice as rapidly as by expert 
craftsmen ; the perfection of the welds being proved by the fact that the 
strength of bars broken by tensile strains at the welds themselves was 
about 92 per cent. of the strength of the solid metal. At the Crewe 
Works Mr. Webb is successfully applying one of these machines to a 
variety of welding-work. The rapidity with which masses of metal of 
various dimensions are raised by them to welding heat is quite under 
control; the heat is applied without the advent of any impurities, as 
from fuel, and the speed of execution of the welding operation reduces 
to a minimum the time during which the heated surfaces are liable to 
oxidise. With such practical advantages as these, this system of electric 
welding bids fair to receive many useful applications. 
Another very simple system of electric welding, especially applicable 
to thin iron- and steel-sheets, hoops, &c., has been contemporaneously 
elaborated in Russia by Dr. Bernados, and is already being extensively 
used, The required heat at the surfaces to be welded is developed by 
connecting the metal with the negative pole of the dynamo-machine, or 
of a battery of accumulators, the circuit being completed by applying a 
carbon electrode to the parts to be heated; the reducing power of the 
carbon is said to preserve the heated metal surfaces from oxidation daring 
the very brief period of their treatment. This mode of operation appears 
to have been practised upon a small scale, some years ago, by Sir William 
‘Siemens, to whom we also owe the first attempt to practically apply 
electric energy to the smelting of metals. 
In his Address in 1882 he referred to some results attained with his 
small electrical furnace, and pointed out that, although electric energy 
could, obviously, not compete economically with the direct combustion of 
fuel for the production of ordinary degrees of heat, the electric furnace 
