What a convenience it would be if all the street lamps of a town could be lighted and put out at once! Mr Lane Fox has proved at a commercial station in the neighbourhood of Fulham that it can be done. All the lamps are connected by wires overhead or underground; to each burner is fitted an electro-magnet composed of a coil of wire round a soft iron core, and above it hangs a movable magnet. The ends of the connecting wires are attached to or detached from a battery at pleasure. When the gas is to be lighted, a current is sent through the wires; the electro-magnet on each burner is excited; the movable magnet swings round, and turns on the gas; a current from a powerful coil is then sent through the wires, and produces a spark at each burner, and thereby lights the gas. The putting out is effected by a reverse current. From twenty to forty lamps have been thus treated, and with entire success; and it is thought that three hundred might be included in the circuit with a like satisfactory result. Thus in order to light up London or any other large town, the lamps would have to be divided into groups of three hundred. The lamplighter, or man in charge of the battery, would of course require to know that none had been missed, and this could be made certain by placing the first and last lamp of the group within sight of his station. If they are alight, then all are alight. The practicability of the operation appears therefore to be settled. The next question is‒Will it prove a saving to the ratepayers? Complaints that ordinary gas-light is not so brilliant as it ought to be, are often heard, and not without reason. The Pure Carbon Gas Company claim for their gas that it is not open to the objections urged against other gas. The process of manufacture has the merit of being very simple, and free from the usual noxious results. At a demonstration made a few weeks since, proof was given that but little space and little skill are required in the manufacture. The tar formed during the process, instead of being carried away as at present, is passed back into the retorts, whereby, as is said, three thousand feet more of gas can be produced from a ton of coal than by the ordinary process. An arrangement is introduced which separates the ammonia and the sulphur, and in consequence this pure carbon gas has but little smell. Ordinary gas is passed as good if it contains not more than twenty-five grains of sulphur to the hundred feet: the quantity in the new gas is less than three grains. We are told that the cost of manufacture is not more than eighteenpence the thousand cubic feet, that it does not require skilled labour, that in consequence of its freedom from smell it could be carried on in a ship or in a house, while its simplicity renders it applicable to villages where at present there are no public lights. The Collinge Engineering Works, Westminster Bridge Road, are mentioned as the place where the demonstration above described was given.