1890.] on Welding by Electricity. 193 



that. You will see that there we have transformed our 100 shillings 

 into a 5Z. note. We are now about to transport the 5Z. note across 

 these wires [they might have been even finer], and we are putting this 

 current into the secondary coil of another Ruhmkorff coil. We shall 

 by this arrangement change the 6/. note into the 100 shillings again, 

 and deliver them through that little incandescent lamp, which will 

 glow, because we have lowered the pressure, and thereby increased the 

 quantity sufficiently to enable us to get a current suitable for that 

 purpose. This lamp, which is glowing, is, as you can see, on the 100 

 shilling circuit ; the other lamp, to which I should have previously called 

 your attention, is on the bl, note circuit, and although the same number 

 of watts are passing through, it is dull, and does not glow. Similarly, 

 if we had put a fine wire from the secondary coil of the first Ruhmkorff 

 to the secondary coil of the second Ruhmkorfi^, that fine wire would 

 have remained absolutely cold. We have taken a piece of the same 

 wire, and put it in position there ; as you will see when I turn on the 

 current, I can melt it. That shows the different effect for heating 

 purposes of a large or of a small quantity of current, and shows, 

 too, that you can vary your electricity, so as to have it in whichever 

 form you please. 



And now, I think, the time has come to describe and to show you 

 the electrical welding machine itself in work. Unhapj)ily, we have 

 not sufficient power at our command in this building to work the large 

 machine. We can only work the second sized one. The drawings 

 that I have here are drawings of the large machine; but if you will 

 allow me, I will describe the machine from the machine itself. 



This is the machine, and in these two pairs of jaws are fixed the 

 pieces to be welded together : in this case pieces of wire rope. The 

 pieces of rope are grasped by the two jaws, which are made of gun- 

 metal. They are in electrical communication with two conductors, 

 and these two conductors are the terminals of a hollow copper core 

 that passes through coils at the back of the machine, these coils 

 being similar to those of a Ruhmkorff coil. Inside these we have a 

 cylinder built up of a number of sheet-iron discs insulated one from 

 another, and round about these there go 70 convolutions of wire, and 

 therefore of the current from the dynamo. That is, the 5Z. note 

 form of electricity passes from the dynamo through these 70 con- 

 volutions of wire. But by the time the^ current has passed through, the , 

 pressure has exhausted itself in producing the shilling state in the 

 copper core and in the conductors connected with it. One of the 

 jaws is movable, and can be forced forward by this screw arrange- 

 ment; the other jaw is fixed, and forms the abutment. This other 

 apparatus is one by which the strength of the current can be regu- 

 lated as desired by the operator ; it consists of a number of lengths 

 of wire, the regulation of the current being performed by the 

 operator switching into or out of the circuit of wire (through 

 which the 5/. note current flows to the machine), a greater or less 

 number of these lengths, thus delivering to the welding machine a 



Vol. XIII. (No. 84.) o 



