water-lines so as to let the stem cut and split the ice, and (2) that the buttock lines should enter the water at a mean angle with the horizontal of from 21° to 30° as a maximum. He explains that with such bows the ice-breaker cracks the ice with the stem, and then rises on to it and breaks it down by its own weight, and shoves it away sideways and downwards. He discusses the value of the spoon-bow, and the angle which the sides of the vessel should form with the vertical, and mentions several recently constructed successful ice-breakers, including the one for the new port of Libau, and alludes to the one for ferrying the train across the Baîkal Lake, and the powerful one called "Ermack," with 10,000 I.HP., now in course of construction by Messrs. Armstrong, Mitchell & Co., intended to keep the passage clear through the Cara Sea in summer, for navigation to and from the Enisëi river, and to keep open the channel to St. Petersburg in winter. There are a great many ice-breakers at work in different parts of Russia, and the Author is glad to find that his views concerning their form have been gradually adopted more and more; but he regrets that they have not yet been carried out in their entirety. Admiral Makarov contributes some remarks differing on some points from Mr. Runeberg, especially with regard to the Arctic Ocean ice-breaker "Ermack." He also makes some interesting remarks about the importance to Russia of extending the use of ice-breakers, so as to increase the duration of the navigation of their extensive waterways all over the empire. C. H. M. one. Danish Ice-Breakers and Railway-Train Ferries. N. AFANASSIEV. (Morskoi Sbornik, November, 1898.) Referring to a Paper by Captain Tuxen, on "Danish Steam Railway Ferries and Ice-Breaking Steamers," read at the International Naval Architects and Marine Engineers Congress of 1897, in London, the Author says his Paper is really supplemental to that He begins by giving some particulars of such vessels built by Armstrong, Whitworth & Co., viz., a train-ferry steamer and separate ice-breaker for Saratov, on the Volga; a combined ferry and ice-breaking steamer for the Siberian railway to cross the Baikal lake; an ice-breaker for Finland; and the largest icebreaker yet made for use in the Kara Sea. All these have one screw propeller at the bows (besides others aft) which is found useful in breaking up the ice. Then follows what is practically a reproduction of Captain Tuxen's Paper. The Author then discusses the proper lines for the hull and trim of the vessel; it should be short, with the largest cross-section well forward of midships, giving a fine run aft, so as to allow the ice which has been forced down by the bows to float up before reaching the propeller, and with a spoon bow; the draught should be much greater aft than forward, and large water-ballast tanks are required at each end of the vessel to adjust the trim according as the vessel is going ahead or astern. He explains various special arrangements about the machinery to meet the exceptional requirements of the work these vessels have to perform. C. H. M. Petroleum Fuel for Vessels of the Russian Navy and (Morskoi Sbornik, July, 1898, p. 129.) The object of this article is to demonstrate the importance of the use of petroleum fuel for the Russian fleet. Thus far it has been found, in workable quantities, only on the northern slope of the Caucasus Range; but there are indications of it on the southern slope also, towards the Black Sea. The Baku district yields 400 million poods (6,450,000 tons), and the other districts 50 million poods (800,000 tons) per annum, and the yield is continually increasing. The Author suggests that 10 per cent. of the total yield should be contributed annually to the Government, by way of impost, to secure a supply of fuel of 40 to 50 million poods (650,000 tons to 800,000 tons) a year for the navy. The use of petroleum fuel dates only about 17 years back. Now all the steamers on the Caspian (about 200) and all those on the Volga (about 1,000) use it, as well as most Russian railways and most of the works in the basins of the Volga, Kama and Oka. The total consumption of petroleum as a fuel has reached 300 million poods (4,840,000 tons) per annum. The Black Sea fleet could be supplied by direct pipe-lines, and for the supply of the Baltic fleet, the Government should form depôts at suitable places along the Volga, which would be supplied by water-carriage from the Caucasus, and from which the oil could be conveyed to St. Petersburg and the Baltic ports by rail or water-carriage. This would make Russia independent of any other country for the fuel supply for her fleet at home; whilst when the vessels are out of reach of petroleum, the furnaces could readily be changed for the use of coal fuel. The trials, hitherto made with petroleum as fuel on vessels of the Russian navy, have not been successful, because they were not properly carried out. The crude petroleum of the Caucasus, which is called raw naphtha in Russia, has a specific gravity of 0.75 to 0.925, and consists of 86 87 per cent. of carbon, 12.19 per cent. of hydrogen, 0.88 per cent. of oxygen, and 0.06 per cent. of sulphur, besides [THE INST. C.E. VOL. CXXXV.] 2 F very minute quantities of lime, oxide of iron, alumina, copper, and traces of silver and gold. The products of distillation are, first, 4 per cent. to 5 per cent. of benzene, which is useless for burning; then 30 per cent. to 35 per cent. of the ordinary kerosene of commerce, leaving a residue of 60 per cent. to 65 per cent., which is called astatki (meaning residue) or mazoot, and which forms the ordinary petroleum fuel. This is commonly called naphtha in Russia, in contradistinction to raw naphtha or crude petroleum. The demand for this fuel is increasing more rapidly than its production, so that the price is going up, and it will soon become necessary to use crude petroleum as a fuel, either mixed with astatki, or by itself; and the Author considers it will soon become a regular practice to prepare crude petroleum for fuel, by heating it, to drive off some of its more volatile compounds. Crude petroleum may be used with perfect safety, even without previous heating. Fresh crude petroleum at Baku does not ignite at a lower temperature than 25° C. (72° F.); after a short exposure to the air this temperature rises to 40° C. (104° F.); after a week's exposure, to 60° C. (140° F.); and after a fortnight's exposure, to 70° C. (158° F.). The temperature of ignition of astatki varies from 80° C. to 170° C. (176° F. to 338° F.), according to the amount of distillation it has undergone. As a matter of fact, about 20 million poods (322,000 tons) of crude petroleum, taken from the tanks at the wells, are now consumed annually at Baku, by the locomotives on the local railways and in the furnaces of most of the works' boilers in the place, without any accidents. The regulations laid down by the Russian Technical Society, in 1882, and which are still in force, are given by the Author. According to these, the use of any liquid fuel, with a flashing point below 56° R. (158° F.), is forbidden. These regulations apply to crude petroleum as well as to astatki. The Author deals with the properties of coal and petroleum as fuels in considerable detail, and summarises the advantages of petroleum over coals for the Russian navy, as follows: (1) economy; (2) speed, cheapness, simplicity and cleanliness of loading fuel; (3) reduction of the number of stokers and of labour generally; (4) absence of ashes or clinkers; (5) continuous and uninterrupted firing; (6) facility of management of the fires; (7) speed with which steam can be raised in case of need; (8) absence of sparks or smoke; (9) the form of the flame can be varied to suit the shape of the furnace; (10) economy of space, and facility of storage and transport; (11) complete combustion without residue; (12) less heat and more air in the stokeholds; (13) facility of checking quantities received and consumed. Although the actual cost of petroleum fuel is somewhat greater than that of coals, wood, or turf, on most of the railways on which it is used, as well as in most works in St. Petersburg, Moscow, and the manufacturing districts, yet its advantages in other respects are so great that its use is spreading in all directions and increasing from year to year. C. H. M. Oil v. Soap-and-Water for Calming Broken Waves. GERHARDT. (Centralblatt der Bauverwaltung, 1898, p. 355.) A short account of some experiments made at sea by Captain Gathemann of the North German Lloyd steamship "Oldenburg to determine the respective effects of oil and soap and water on a heavy and broken sea. The soap and water was composed of 7.5 kilogrammes (16.5 lbs.) of green soap to 40 litres (8.8 gallons) of water. The "Oldenburg" is 132 6 metres (435 feet) long, and the oil or soap and water was dropped from the forward water-closets, 24 metres (79 feet) from the stem, when the ship was travelling at a speed of about 12.5 knots. The oil used amounted to about 1.25 kilogrammes (2.7 lbs.) per hour and was most effective; the soap and water, contrary to the results of Professor H. Köppen's experiments, proved quite useless. W. B. The Sparking of Commutators. H. F. PARSHALL, M. Inst. C.E., and H. M. HOBART. (Engineering, 16 September, 1898, p. 349.) Great improvement has recently been made in the sparkless collection of commutated currents, with constant position of brushes. Radial bearing carbon brushes are now extensively used, while the commutator segments are insulated by mica, wearing at the same rate as the copper, and remaining even therewith. The avoidance of sparking depends on an understanding of armature interference. In the formula E = KTMN 10 - 8, T and M must have such relative values as to fulfil the necessary conditions for sparkless collection of the current and regulation of the voltage with varying load. The brushes must be so placed that each coil, when in contact therewith, shall be in a magnetic field of the direction and intensity necessary to reverse the current it has just been carrying. Under such conditions there is no sparking. But as the current output is increased, a stronger field is necessary to reverse it, while this stronger current so magnetises the armature as to distort the field, and weaken the magnetic flux. The shifting of the brushes further intensifies the demagnetising effect of the armature. Finally, a current output is reached at which sparkless collection is impossible. Experiments have been made to ascertain the distribution of the magnetic flux in the gap by means of an exploring coil. The excitation of the field was maintained constant. Curves are given showing the distribution of flux with various positions of the brushes, which show that the total magnetic flux, as represented by the area of the curve, is the same with no current in the armature as with the full load current with the brushes at the neutral point. The distribution is, however, different. A. P. H. The Multiple-Resonance of Electrical Oscillations. L. DECOMBE. (Archives des Sciences Physiques et Naturelles, vol. v., 1898, p. 121.) The Author has photographed, by means of a revolving mirror, the discharge of a condenser made as follows: Twelve plates of brass, 15.7 centimetres by 28.9 centimetres, were fixed parallel to one another 2 centimetres apart. A brass bar on each side connected the alternate plates, and the whole was immersed in a bath of oil. Two solenoids of brass wire 4 millimetres thick connected the condenser with the spark-gap, which consisted of two adjustable spheres in a glass vessel filled with vaseline oil, beneath the surface of which the spark was taken. The revolving mirror made from 400 revolutions to 500 revolutions per second. The photographs show about fourteen oscillations. On careful measurement with a dividing engine the oscillation period was found to be constant throughout the entire duration of the discharge, disproving the hypothesis of Swyngedauw, according to which the heating effect of the spark should cause a diminution of the period, and confirming Feddersen's experimental proof that the period is independent of the resistance. G. J. B. The Earthquakes of the United States. F. DE MONTESSUS DE BALLORE. (Archives des Science Physiques et Naturelles, vol. v., 1898, p. 201.) The Author has collected statistics of 5,121 earthquakes in 588 localities, which he has grouped together in 14 districts. With the exception of the New England district, for which the data go back to 1725, most of the records relate to the last 50 years. Under each district he gives the names of the localities, with the number of earthquakes in each, and the Paper is accompanied by a map in which the relative seismic activity of the various regions is indicated. G. J. B. |