made to the car by a flexible running conductor. The greatest difficulty experienced so far has been in the attempt to regulate the flow of water to the wheel by an automatic governor, the trouble being that the stoppage of a car throws off instantly 80 to 85 per cent of the work from the turbine, so that an immediate corresponding decrease of the water supply must be made; on the contrary, in starting the car the water must be turned on again gradually. When it is added that Sir Wm. Thompson now occupies a position in the board of managers in place of the late Sir William Siemens, it will be seen that the electrical arrangements of this road are and have been in the best of hands. The following details may be of interest. Two loaded cars upon the worst gradient require a current of 60 ampères, the maximum potential being 250 volts. The resistance of conductors from the generating station to Portrush and back is less than 2 ohms, while the resistance of the insulation ("insulite ") of the conductors varies from 500 to 1000 ohms, according to the weather. The total leakage along the line may be as much as 2.5 ampères, or ₫ H. P. In eight months after the opening, 13000 "electric-car miles" were run, the daily run in summer being 100 car miles with 600 to 800 passengers. For nearly a year previous to Nov., 1883, steam cars were used on the line so that a reliable comparison between the cost of running by electricity and by steam can be made. The cost of running by steam, including the wages of attendants, coke, oil, etc., was ten cents per mile run, while with electricity this was reduced to less than four, and with such additional traffic as could easily be accommodated with the existing plant it would not be over two and one-half cents. Experience also warrants the prediction that "on a more favorably circumstanced tramway, with a service of single cars, running at short intervals, the working expenses might be reduced to d (one cent) per mile run, and that even though the electricity should have to be generated by steam power." It would seem from an inspection of the detailed expenses of running, that, owing to the higher wages paid here, the comparison, while leaving a large margin in favor of electricity, would not be so overwhelmingly against steam except in localities where abundant water power is available. "parlia The cost of the line has been $150,000, as follows: mentary law, engineering and preliminary, $15,000; construction of six miles of tramway, one mile of branch and sidings, buildings, carriage and engine sheds, $80,000; water-power generating station turbines, electric conductors and cables, $22,500; electric plant, generating dynamos and motors, $10,000; rolling stock; two tramway engines, nine tramway cars, fourteen wagons and mineral trucks, $22,500." The road is understood now to be not only in successful and continuous working, but in a paying condition, which recommends it to the careful study of those interested in such matters in the United States. ELECTRIC TRAMWAYS. By M. HOLROYD SMITH, Fern Hill, Halifax, England.1 [ABSTRACT.] To demonstrate the practicability of Mr. Smith's system of electric tramways an experimental line has been laid in a field near the works of Messrs. Smith, Baker & Co., Manchester, England. The track is 110 yards long and 4' 8" gauge; it is essentially level and the car is driven by the traction of the ordinary wheels, but it contains some sharp curves. On the latter account one wheel on each axle is loose and the power is distributed between the two wheels on the axle by differential bevel gears, so that both wheels drive equally well on curves and straight line. The movable bevel gear in this arrangement is driven by a steel chain from a Siemens motor and the current is brought up from an underground conduit, which forms the main feature of the line. This conduit is constructed in much the same manner as a cable line, with a copper conductor in place of the cable. This copper conductor is double and consists of two half tubes,-as if a tube had been cut in two lengthwise and vertically and the two halves separated somewhat from each other. In this tube, then, a shoe slides, being connected both electrically and by leather straps with the car, the leather straps breaking should the shoe be accidentally obstructed, as by pebbles jammed in the groove. The rubbing part of the shoe, or shuttle, consists of spirally-grooved rollers, whose axis is that of the tube, and whose slow revolution, caused by friction, keeps the tube cleaned out perfectly. The rails answer 1 Mr. Smith not being present the paper was read by Mr. Preece. Abstract by the Secretary. for the return current. This method of supplying the electrical current to the cars is so successful, and the conductor is so well protected in the underground channel, that after a week's rain the leakage, if any, was so small that the improved contact of the moist shoe prevented any difference from showing in the speed of the cars. (It would seem that this system would be specially fitted to replace the cable system so soon as a sufficient economy of power can be shown in its favor.) ARE THE ADVANTAGES OF A TRIP GEAR WORTH ITS GREATER COST THAN EXCENTRICS? By ARTHUR RIGG, President of the Society of Engineers, London, England. [ABSTRACT.] THIS paper discusses the construction of "trip-gear" regulated engines, as compared with the action of double excentrics. Its conclusions are based upon the idea that the use of such gear limits the revolutions of an engine to a rate considerably below that of any other parts of its construction. Therefore the first cost of such engines is rendered excessive. It is then pointed out that two excentrics can cut off steam through any desired range with a speed sufficiently great for all practical purposes, and the author concludes that any arrangement of valves now worked by trip-gear could be equally well driven by double excentrics with the advantage that the number of revolutions and power of such engines might be considerably increased. THE STRENGTH OF CAST IRON. By W. J. MILLAR, C. E., Secretary Institute of Engineers and Shipbuilders, Glasgow, Scotland. [ABSTRACT.] (1) Object of paper:- Results of tests of strength of cast iron (made in Glasgow). (2) References to former experiments by the author. These summarized are: (3) The test bars used were 40" long, 2" deep and 1" broad. Span 36", loaded at centre. (a) Deflection varied fairly with load. (b) The "set" decreased with successive applications of the same load and even for increased loads ;-ultimately disappearing. (c) The fracture when at centre of span was straight; when at points more or less removed from centre it was curved. (4) Recent Experiments. Influence of vibratory action on bars and tensile links, from which the author finds that bars and links may be broken by striking with light and continuous blows, even although the load at the time may be considerably below the ultimate load, the deflection and extension increasing with each blow. (5) The average transverse strength of 30 bars was found to be 3476 lbs., deflection .390 inch. The tensile strength of 15 links of same metal was found to be 11 tons, 11 cwt. (6) Equations derived are as follows: T= WXS XW= 2 × TX bd2 where T tenacity in tons sq. in.; W = ultimate load T = in cwt. at centre of bar; S = span in feet, b and d being breadth and depth in inches. (7) Bars and links cut out of casting give much lower results than bars and links cast separately, say 30 per cent less. A MODE OF HEATING FROM A CENTRAL SOURCE. By Sir FREDERICK BRAMWELL, F.R.S., V. P. Inst. C. E. [ABSTRACT.] A DESCRIPTION of the method of warming employed in the Third Middlesex County Lunatic Asylum, Banstead, England, where the circulation of warm water is produced by centrifugal pumps which maintain parallel mains in a relatively plus and minus condition. FLOOD REGULATOR. By JAMES DILLON, C. E., Glengeary, Co. [ABSTRACT.] THIS flood regulator is used for two purposes: to reduce the cost of river excavations or conservance works by reducing the volume of flood sent down a river in a given time, and for preserving for dry seasons some of the waters now allowed to pass to the sea in wet seasons unused. The author has effected this in places where large natural lakes are found to exist at the head of a river system proposed to be improved, by increasing the natural range of the lakes one, two or more times more than their ancient range between high and low water by deepening the river channels into them; of course this operation would in itself increase instead of diminish the flood discharge. To prevent this increase, he constructs large self-acting sluices on down-stream side of lake, kept open in dry seasons, having their sills to correspond with the new low water level of the lakes. On the floods entering the lakes they escape through these sluices, and by the time the maximum discharge is reached the sluices are closed, gradually, by the action of iron floats rising with the flood surface of the lake; then by the time the sluices are completely closed the maximum calculated flood discharge is found to be passing through the permanent boat or ship-pass at all times kept open at one side of the weir for the preservation of watersupply to lower countries, for navigation, fishing and other rights. This maximum flood discharge, however, cannot be reached through this ship-pass until the lake is made to withdraw from the ancient maximum floods the increased flood volume required for dry seasons, and by operating on the regulating screws attached to the sluices, ordinary floods can be reduced or increased with the greatest nicety, etc. AUTOMATIC SOUNDER. BY JAMES DILLON, C. E., Stratford House, Glengeary, Co. Dublin, Ireland. [ABSTRACT.] THIS instrument has been successfully used for some time by the author for preparing soundings of lakes, harbors, estuaries, rivers, for chart and sections, etc. |