PROGRESS IN ENGINEERING.
Mr. T. Forster Brown, in his address to the Mechanical Science Section of the British Association, said that great progress had been made in mechanical science since the British Association met in the principality of Wales eleven years ago; and some of the results of that progress were exemplified in our locomotives, and marine engineering, and in such works as the Severn Tunnel, the Forth and Tay Bridges, and the Manchester Ship Canal, which was now in progress of construction. In mining, the progress had been slow, and it was a remarkable fact that, with the exception of pumping, the machinery in use in connection with mining operations in Great Britain had not, in regard to economy, advanced so rapidly as had been the case in our manufactures and marine. This was probably due, in metalliferous mining, to the uncertain nature of the mineral deposits not affording any adequate security to adventurers that the increased cost of adopting improved appliances would be reimbursed; while in coal mining, the cheapness of fuel, the large proportion which manual labor bore to the total cost of producing coal, and the necessity for producing large outputs with the simplest appliances, explained the reluctance with which high pressure steam compound engines, and other modes embracing the most modern and approved types of economizing power had been adopted. Metalliferous mining, with the exception of the working of iron ore, was not in a prosperous condition; but in special localities, where the deposits of minerals were rich and profitable, progress had been made within a recent period by the adoption of more economical and efficient machinery, of which the speaker quoted a number of examples. Reference was also made to the rapid strides made in the use of electricity as a motive power, and to the mechanical ventilation of mines by exhaustion of the air.
COAL MINES.
Summarizing the position of mechanical science, as applied to the coal mining industry in this country, Mr. Brown observed that there was a general awakening to the necessity of adopting, in the newer and deeper mines, more economical appliances. It was true it would be impracticable, and probably unwise, to alter much of the existing machinery, but, by the adoption of the best known types of electrical plant, and air compression in our new and deep mines, the consumption of coal per horse power would be reduced, and the extra expense, due to natural causes, of producing minerals from greater depths would be substantially lessened. The consumption of coal at the collieries of Great Britain alone probably exceeded 10,000,000 tons per annum, and the consumption per horse power was probably not less than 6 lb. of coal, and it was not unreasonable to assume that, by the adoption of more efficient machinery than was at present in general use, at least one-half of the coal consumed could be saved. There was, therefore, in the mines of Great Britain alone a wide and lucrative field for the inventive ingenuity of mechanical engineers in economizing fuel, and especially in the successful application of new methods for dealing with underground haulage, in the inner workings of our collieries, more especially in South Wales, where the number of horses still employed was very large.
STEAM TRAMS AND ELECTRIC TRAMS.
Considerable progress had within recent years been made in the mechanical appliances intended to replace horses on our public tram lines. The steam engine now in use in some of our towns had its drawbacks as as well as its good qualities, as also had the endless rope haulage, and in the case of the latter system, anxiety must be felt when the ropes showed signs of wear. The electrically driven trams appeared to work well. He had not, however, seen any published data bearing on the relative cost per mile of these several systems, and this information, when obtained, would be of interest. At the present time, he understood, exhaustive trials were being made with an ammonia gas engine, which, it was anticipated, would prove both more economical and efficient than horses for tram roads. The gas was said to be produced from the pure ammonia, obtained by distillation from commercial ammonia, and was given off at a pressure varying from 100 to 150 lb. per square inch. This ammonia was used in specially constructed engines, and was then exhausted into a tank containing water, which brought it back into its original form of commercial ammonia, ready for redistillation, and, it was stated, with a comparatively small loss.
IMPROVED CHANGEABLE SPEED GEARING.
This is the invention of Lawrence Heath, of Macedon, N.Y., and relates to that class of changeable speed gearing in which a center pinion driven at a constant rate of speed drives directly and at different rates of speed a series of pinions mounted in a surrounding revoluble case or shell, so that by turning the shell one or another of the secondary pinions may be brought into operative relation to the parts to be driven therefrom.