A vacuum can now be produced almost perfect. It is of course impossible to extract every tiny particle of air from the globes, but by the Sprengel pump, in which mercury is employed, excellent vacuums are obtained. Several very curious phenomena have been observed in these vacuums, and the Royal Society has been engaged upon their consideration. Another advantage of the vacuum, as applied by Edison, is that little or no heat is generated. The electricity is all, or very nearly all, converted into light. Thus the glass globes remain almost unheated, and are unbroken. The electric current passes along the wire, W, and at a certain place marked B, the copper is soldered to a platinum wire, which enters at C, and so by platinum clamps into the horse-shoe, L. The return wire is similarly arranged; the carbon is enclosed in a glass bulb, GG, and all the air is extracted by the pumps; the end is then sealed up by melting it at F. The world is now in possession of a lamp for household use, and we are surprised that it is not more extensively adopted in England. There are some Swan lamps used in parts of the British Museum, and when we have explained the application of the light, and the uses to which the motive power can be applied, we shall, we believe, convince the most conservative gas bill advocate that Edison’s lamp is cheaper, safer, and far better in illuminating power than gas, if the success of the electric lamp can be assured. We need not dwell upon the construction of the “pumping station,” for that is virtually what the magneto-electric generator is. Several of these stations can be established in various parts of the city, and each station will supply a district with electricity. The wires are laid in a tight box along the street, beneath the footpath, or other convenient position, and we are informed that the frost rather improves their electrical condition. Here is one advantage over gas. From the main wires smaller ones enter the houses, and are carried through a “meter” containing a safety valve. There are two wires—a distributing wire and a waste—coloured, one red and the other green, which communicate respectively with the main supply and return wires to the “pumping station” or generator. The electricity is admitted between carbon points and flows round a magnet, the armature of which is held above it by a spring. If too much force be put on and any danger incurred, the magnet will attract the armature, and the current will cease. A snap connected by a small wire will then be closed by the electricity, and melting from the heat will cut off all the current. In ordinary circumstances the electricity passes through regulators (wire wound on spools) and on to a copper plate, “through a solution of copper salt.” Thus for every unit of current a certain quantity of copper is deposited. A certain standard amount represents five cubic feet, and the bills, based on the accumulation of copper, are made out like gas bills.