[Fig. 32] illustrates a method proposed by Mr. Kenneth Mackenzie, which is somewhat similar to the system of conduit which, used at Tours for the past two years, has been found most efficient for the high potential supply mains to the transformers. The troughs would be about 4 ft. long and 15 in. deep, having spigot and socket joints at the ends like ordinary water pipes. Transverse pieces of wood, or preferably slate, would rest upon projections, and would support the mains, and a cover recessed as shown would make the conduit fairly water-tight; drain holes would be provided, and the branches to houses led off through glands in the side of troughs. The American plan is, doubtless, the best, as there is no space for moisture to collect in the conduits; but Mr. Mackenzie’s system is well worth trying, and has the advantage of being much cheaper in first cost.
The Edison plan is to place two solid conductors in a tube which is filled up solid with an insulating material, suitable bends and offsets being supplied, so that the tube containing the two conductors can be buried in the ground like a gas-pipe. The system is very largely used both in the United States and in Continental cities; but it is doubtful whether the protection would suffice in our towns, where the streets are already at the mercy of the gas and water companies, whose workmen, with a single blow of a pick, might perforate the tube, and cause a dangerous short circuit.
The Interests of Gas Companies
as to Electric Lighting.
The policy of gas companies with regard to electric light has, with few exceptions, been a state of indifference to the progress of things electric, with contempt for a rival whose opposition is not sufficiently powerful to be appreciated. The chairman of a well-known gas company stated, what is undisputed,—that the introduction of electric arc lights was accompanied by an increased consumption of gas in the immediate neighbourhood where these lights are used; but it is very doubtful whether this will be the case when incandescent lights are generally supplied. The introduction of these lights into any business district would mean the displacement of at least as many burners as there are electric lamps; and this reduction not only means loss of income, but also loss by interest on plant which is not kept at work to the capacity for which it was designed. The question suggests itself, “Are existing gas companies more favourably situated for furnishing electricity than any one else?” There are many reasons in favour of the supposition that the directors of gas companies have at the present time an opportunity of acquiring almost as complete a monopoly of lighting by electricity as they have with gas. As regards central-stations, everything is in their favour; there is generally some spare ground for the machinery, waste heat could be utilised, and a cheap fuel in the shape of coke is ready to hand. They have greater facilities for breaking up streets without danger of troubles arising with the local authorities, and if the Gasworks Clauses Acts, which authorise their existence, tie them down to one illuminant, a very little expenditure would enable them to enlarge their powers. In many towns the shareholders are local men who wish to use the electric light, but cannot favour its introduction because they think it would tend to smaller dividends or lower quotations for their shares; if, however, a scheme was promoted either by the gas company, or, if that was impossible, if the directors interested themselves in a separate electric light undertaking, the security which the gas and water investments command would, no doubt, cause a sufficient number of local subscribers to come forward and make even a small installation a paying concern. The Imperial Continental Gas Association have already taken up the supply of electricity in Vienna, and are likely to extend this new branch of their business to the other cities in which they hold gas concessions; also in the United States the growing opposition of the electric light companies is being seriously discussed, and already several gas companies are installing electric light plants.
It is not at all probable that the scare which caused such a drop in the value of gas shares when the electric light first appeared will be repeated, but the present high price of gas shares cannot be maintained. Kerosene lamps have been for some time a far greater rival to gas than electricity. The cheapening of petroleum, which is now shipped in bulk to this country in tank steamers, will cause the consumption to increase, and enable the oil to be supplied at a price so that it can be used in petroleum-engines, and give a motive power which will be found to be far more economical than the gas-engine. The latest development of petroleum-engines is that shown by Messrs. Priestman at the Royal Agricultural Society’s Show at Nottingham. The engine in external appearance is like the Otto gas-engine, but uses the ordinary “paraffin oil” of commerce, which has a high flashing point. The oil is simply put into a closed tank, and on the top of this, air is forced which drives the petroleum into a chamber heated by the exhaust from the engine, where it is partially vaporised and led into the cylinder with sufficient air to cause it to ignite by means of an electric spark.
The report of the trials with a 5 horse-power engine show that a brake horse-power was obtained for 1·7 lb. of oil, or at 6½d. per gallon for 1·4d. per horse-power per hour; with the Spiel engine the cost is stated to be 0·8d. per horse-power per hour.
Any serious reverse to the gas industry would cause a great pecuniary loss to a large number of investors. The paid-up and borrowed capital devoted to the manufacture and supply of gas in the United Kingdom exceeds £56,000,000, of which above £36,000,000 appertain to the companies and the remainder to the local authorities, whose receipts in respect of their gas undertakings last year exceeded £4,400,000.
The corporation of Bradford, who are owners of the gasworks, have wisely foreseen that it is better to keep the electric light in their own hands, and are now about to erect a central-station, and will lay underground wires; the amount sanctioned for this preliminary installation is £20,000.
The Lucigen Light.
A few remarks on this method of obtaining light from the combustion of crude petroleum may be added, as the light has been put forward as a cheaper and better substitute for the electric arc. The Lucigen light is produced by burning creosote oil, tar oil, or other heavy hydro-carbons, by means of compressed air in a special form of lamp, and consists of a cylinder at the side of which a steam donkey compressing pump is mounted, or in a more recent form known as the Wells’ light, no separate air compressor is used, but, instead, the pressure is obtained from the water mains or from a small force pump. The cost is stated to be 3d. per hour for 2,500 candle-power, requiring three gallons of oil per hour, but is in reality at the present time double this owing to the price of the oil, which, under the most advantageous circumstances, costs on average 2d. per gallon. At the Forth Bridge these lights have been found of use in illuminating open spaces, but have not supplanted the electric arc lights which are universally employed for the lighting of the works and the interior of the shops. The disadvantages are the noise, the oil shower which pervades the vicinity of the light causing timber staging to be highly inflammable, and the difficulty of preventing water from entering the burner, a few drops sufficing to extinguish the light. The use of the Lucigen light is, therefore, very limited, and it is probable that, in situations where shadows from the arc light are found to be objectionable, large incandescent electric lamps, which are supplied up to 1,500 candle-power, would meet the case; or, failing these, petroleum could be burnt in lamps similar to those used in lighthouses with greater safety, and at not much increased cost, than the compressed-air system.