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6 MARINE An Aluminum Boat from Scientific Builders. A boat weighing only 10 tons with steam up and coal in the bunkers, but capable of developing 20} knots speed under 300 horse power, 1s a remarkable example of progress in naval architecture. Sucha boat is the second-class aluminum torpedo vessel, just completed by Messrs. Yarrow & Co.,the famous British builders of torpedo vessels, for the French government. The boat isof the dimensions now usual with second class torpedo vessels, being 60 feet long and 9 feet 3 inches wide, and is the largest aluminum boat of any kind afloat. Her machinery con- sists of a set of triple expansion engines, driving an aluminum bronze propeller at 580 to 600 revolutions per minute. These engines are balanced ALUMINUM TORPEDO BOAT. without bob weights at'two points only, the balance weights being fitted at properly calculated angles to the cranks. The boiler is of the ordinary Yarrow water-tube type. The object of what is termed a second-class torpedo boat is to be car- ried on the deck of large men-of-war, to be lowered in the water and to act, when necessity requires, ds a scout to watch the movements of the enemy's torpedo boats, or for the use of the ship for landing and embark- ingthe officers. Itis self-evident that lightness of construction is of paramount importance in craft of this kind, not only because reduced displacement secures increased speed, but, considering that the boat has to be lifted and lowered by the tackle available on board the ironclad or other vessel, it is clear that the weight to be handled should be reduced toaminimum. The French navy up till last year had not adopted boats of this kind, but when it was decided to build some of them the right to submit proposals was not confined to French builders. The proposal sub- mitted by the British firm was the one accepted, as they were prepared to guarantee a higher speed and lighter weight to be lifted than any other firm, mainly in consequence of having determined to adopt aluminum for the construction of the hull. Comparatively little has hitherto been known about aluminum as a structural material, and before adopting it Messrs, Yarrow & Co. carried out a series of elaborate experiments on the metal to obtain information. The success of this firmis largely due to their elaborate system of ex- periments in all ventures. The trials of aluminum referred to its stiff- ness, best working temperature, corrosion, etc. It was found, in the first place, necessary to alloy the metal, by which its tensile strength was raised from 9 tons per square inch to about 18 tons. The alloy is mainly 6 per cent. of copper. As regards stiffness, etc., a general result was ' arrived at. All scantlings were increased 25 per cent. over that allowed for steel, and as aluminum weighs about one-third of steel, it follows that areduction of about one-half was effected in the weight of the hull, which was reduced from about four tons for steel to about two tons for alaminum. In order to arrive at some precise information concerning corrosion, two aluminum plates were accurately weighed, and then secured on the sides of a wooden coppered sailing ship, the copper being removed and replaced by the aluminum. This ship made a voyage around the world, then the aluminum plates were removed, weighed, and found to have suffered no appreciable loss. The great foes to aluminum are alka- lies, which attack it powerfully, and heat. It fuses at a moderate heat, and loses much of its strength at comparatively low temperatures. In the case of a torpedo boat there is no trouble incurred in avoiding both sources of risk. No plates or angles were touched by the fire; everything was bent cold. The frames area little closer together than they would be if of steel. The stem and stern frames are of galvanized steel, and the chimney is also of steel, though the outer casing to itis of aluminum. The deck plates over the boiler space are likewise of steel, it being con- sidered unwise to subject aluminum tothe danger from distortion that might arise through heat. The extra cost of material in the use of this particular boat was $5,000 as compared with that of steel. In return there is a saving of about two tons in weight and a gain of about 3% knots in speed over vessels of the same class and dimensions in the British navy which steam under the like conditions at 17 knots. The extra cost is, of course, the crucial . point, and to judge from experience with this little boat, there does not seem much probability that the new metal will be largely used for ship building purposes for many years to come. In vessels like the torpedo REVIEW. boat chasers, of which a large number are now being built in Englan d, the cost of aluminum would be considerably over twice as much as steel, During a trial of this boat of two hours' duration the engines made 70,948 revolutions, being at the rate of 591.2 revolutions per minute, correspond ing to a mean speed during the entire run of 20.558 knots per hour. The description and engraving is from the Engineer of London. Stocks of Grain at Lake Ports. The following table, prepared from reports of the Chicago board of trade shows the stocks of wheat and corn in store at the principal points of gecuimulation on the lakes on Oct. 13, 1894: Wheat, bu. Corn, bu. iin bo BED EE Te SANE 25,349,000 1,674,000 See ae sas ieee B318,000 ev Mivierece piudi sity 200" iba oon 76,000 "Ra ere Koysnends ndbboondeSedasbocdde ogg Gn0bSdo00 3,436,000 24,000 Busalow ees AR ae. BES 2,283,000 270,000 Metal toe, «saat os coc ceeteacenens 36,694,000 1,984,000 At the points named there isa netincrease for the week of 280,000 bushels of wheat, and a net decrease of 103,000 bushels of corn. Mining Notes. At the Mountain Iron, the principal Rockefeller syndicate mine on the Mesabi, the body of ore now uncovered is 1,200 feet long and 500 to 600 feet wide. A deep cut the entire length of the stripping is open for steam shovel work. It is claimed that if a great output was desired 9,000 to 10,000 tons could be loaded daily without a heavy expenditure for further stripping. The Mountain Iron's shipment this season are now about certain to aggregate 600,000, so that with about 500,000 tons from the Oliver and smaller amounts from other mines on the new range, the entire output of the Mesabi will be above 1,500,000 tons. The Franklin had shipped 190,000 tons on Oct. 15, and will have a total output of about 220,000 tons. Probably of all the mines of the Marquette range, the Pewabic, which produces a high grade ore, and in which the Carnegie company is part owner, will make the best showing. Its output to Oct. 1 this year was 265,000 tons. For previous years the best record of this mine was 265,745 tons, shipped in 1893. Although mining operations will not be suspended at the Chapin on account of the sale to take place a few days hence, all shipments will be stopped at the time of the sale,in order to settle accounts between old and new owners, whoever the latter may be. Shipments of ore from the Canton, one of the Minnesota company's properties on the Mesabi, are practically at an end. Stock piling was commenced at one of the shafts last week. The output of the mine is estimated at 225,000 tons. . Obituary. CAPT. THOMAS. HARBOTTLE. Capt. Thomas Harbottle, steamboat inspector for the port of Toronto, died suddenly of heart failure on Friday last. He was seventy years of age and had held the position of inspector since 1883. Previous to that time he commanded a number of Canadian vessels, among them the Prin- cess Royal, Passport and Chicora. His home for about fifteen years was in Hamilton and the burial occurred at that place. Of seven sons who survive him, three are in command of lake vessels, and two are pur- sers on large passenger boats. CAPT. F. G. BOOTHMAN. Capt. F. G. Boothman, who was known in all parts of the lakes as the master of several Canadian vessels, and who was later in the American steamers Progress, Rust and Alcona, died at his home in Cleveland, Sunday. His illness was short. The remains were taken to Hamilton, Ont., for burial. Capt. Boothman was only thirty-six years of age but he was a very capable master and his services were highly regarded by his employers. He had been in the Alcona for three seasons past. A light to indicate the location of the government wharf at Sault Ste. Marie, on the Canadian side of the River St. Mary, between Lakes Huron and Superior, was put in operation on August 10. The light is fixed red, shown from a square tubular lantern hoisted on a pole. It is elevated 14 feet above the level of the river and should be visible two miles from all points of approach. The mast stands on the wharf 25 feet from its south east corner, : The color of the tower at Milwaukee pierhead light station has been changed from white to gray, and that of the fog signal houses from white to brown Capt. Philip M. Price of the corps of engineers, U. S. A., whose death was announced recently, was engaged on the survey of the great lakes.