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14 MARINE REVIEW. Instructions for Use of Howden Draft. Now that some forty steam vessels on the lakes, of various kinds, and most of them of the largest type, are fitted with the Howden system of hot draft, the management of the Dry Dock Engine Works of Detroit, controlling patents on this draft, has issued instructions to engineers, with a view to getting the very best results fromthe appliances. This system of draft is, of course, very simple, and officials of the dry dock company say that there is no difficulty whatever in having engineers and firemen understand its main principles, but they realize that the great demand for economy in fuel from this time on is going to require care in every detail of cost connected with making steam, and they want to bring out the full advantages of the draft. They have accordingly issued the following instructions: FIRE BARS AND FURNACES. 1. The side bars must be fitted close to the sides of the furnace so as to prevent air from passing up at the sides. Fire clay should always be kept in the recess made for the purpose. The dead plates must also be air tight at the sides. 2. Care must be taken to have all the fire bars fitted so as to have no slackness sideways when working. 3. Thin bars should be used to pack the bars sideways should the last bar of the ordinary thickness to be put in be too thick for the space. The proper allowance for expansion of the bars under heat must be al- lowed for lengthways. 4, No air whatever must be allowed to pass through the bridge from the ashpit. Air must pass from the ashpit through the fire grate only. If the tubes are clean when starting, the boilers may run with the retarders continuously for a fortnight (if the fires are properly worked) before requiring to be cleaned by the steam jet. FIRING. The highest evaporative power combined with the highest economy will be obtained with the least labor by carefully attending to the follow- ing directions : "i 1. In firing, the coal must be maintained nearly level across the fur- nace, and always a good height at the bridge. 2. The coal must not be heaped upin front, as is usual in natural draught boilers, or lie against the cast-iron boxes inside the furnace fronts. When the fire is too high in front, the air from the cast-iron boxes at the sides of the furnace, and from the box on inside of the fur- nace door, is prevented from striking over the level of the fuel and effect- ing its proper combustion. Heaping coal up near the furnace door also destroys the air boxes, and consequently causes the admission of too much air to the furnace without increasing the combustion. All un- necessary use of airin the furnace wastes fuel. The air boxes at the sides of the furnaces and on the inside of the furnace doors should keep in order for a year if the firing is properly done. 3. The fires should never be so thin as to allow air to pass up too freely through the fuel, nor should the fires be too thick to prevent the ignition of the fuel all through. When thick fires are used, they should be opened up by the slice shortly after firing. 4, As thecoal burns more quickly at the sides and the back, care must be taken to lay the coal well in at the sides in firing, and to push it back when leveling before firing. 5. Fresh coals should not be thrown on the fires before the fires are levelled with the light rake. The rake should be used to level the fires after they are well burned and a short time before firing. When this is regularly done the surface of the fires will always be easily keptin good order. Note.--Heavy smoke with distillation of gas and production of soot, causing deposits of tar and soot on the back tube plates and in the tubes, and which sometimes also causes flaming in the uptake and funnel, is entirely due:to the coal being allowed to lie in a dead mass without a sufficient quantity of air being passed through it. CLEANING FIRES. 1, All fires must be cleaned from the top and never pricked from below. Pricker blades should not be allowed on board. When the light is not seen shining through the bars from the window in asphit door, the fire is either too thick, and requires to be opened up from above by the poker, or clinker has formed on the firebars, preventing the passage of air through the coals. The heavy slice must then be used and the sharp chisel end made to pass over the top of the firebars and lift up the clinker from them. The window on asphit door shows when the fires require the poker or slice. Solong as the light shines through the firebars into the asphit no poker or slice is required in the furnace. Examination through the window will generally show the part of the grate where the combustion is most retarded. WORKING AIR VALVES. 1. Thetop air valve should not be shut when firing or even in cleaning fires. It should be set by the engineer to suit the kind of coals ia i lk, being used when starting, and never moved during the voyage unless to prevent steam blowing off when the engines are stopped. 2. Before opening the furnace door for firing, the asphit valves must be shut. and opened again whenever the dooris shut. When steam is rising faster than is wanted, shut one asphit valve, and if that is not sufficient, shut both valves. Should steam still rise, shut the upper valve also. 3. When working natural draught shut both asphit valves, open asphit door, and keep the upper valve full open. Never open the furnace or smokebox doors to keep down steam, as the combustion is perfectly controlled by the air valves. Be careful when working to have the fur- nace and asphit doors perfectly closed. WORKING A NUMBER OF BOILERS TOGETHER, To maintain a constant and full supply of steam when working a number of boilers together, each fireman should work the furnaces under his care as if there were no others in the ship. As each fireman will use different quantities of coal and will give the fires different treatment, a number of men firing merely by rotation will always bring the fires into an irregular and unfavorable condition, Likewise, the cleaning of fires should not be left merely to be done at a given hour. Somecoals very soon run aclinker over the bars and prevent combustion from below, which will reduce the effect of the furnace from one-half to two-thirds. Whenever the mica windows (which should always be kept clean) do not show the light shining in the asphit, the slice must be used to lift the clinker from the bars. It is not always necessary to remove alltheclinker. If it is turned on edge it will not hinder combustion, and it can be removed at convenience. The frequent use of the slice to clear the firebars from clinker, and par- tial cleaning of fires whenever required, will always keep the firesin the the best condition and make the thorough cleaning of the fires at the usual intervals a much lighter operation, which should occupy only a few minutes' time. Cleaning fires with this forced draught should in no case cause any drop insteam pressure. Though one fire in each boiler was being cleaned simultaneously, the steam pressure should be fully maintained. This is easily accomplished by the simple rule that no fireman begins to clean a fire until the other fires under his care are put in good condition, with a proper charge of coal on each and full air pressure below bars. Following this course in some steamers with single boilers, having three ~ furnaces only, the engines are maintained at full speed, and the safety valves made to blow off while cleaning fires. An equal effort should be aimed at also in high-powered steamers with many boilers. Treatment of fires, whether in firing, slicing, dressing, or cleaning, should be done rapidly. Fartoo much timeis generally taken sorting fires. Suitable tools for each fireman should always be lying at his hand, so as to pre- vent loss of time in completing his operations. Following these in- structions, every fire should always be in good order and steam plentiful. A Deposit of Asbestos. A large body of short fiber asbestos was discovered some time ago in White county, Ga. The asbestos rock in this body is about 350 fee, wide, 950 feet long, and as far as known, 60 feet deep. The material in this rock is not adapted for textile fabrics but is especially valuable for paper pulps, cement and for bricks for lining furnaces, heaters and grates. The bricks can be cut directy from the rock. For other pur- poses the rock needs only to be milled, no separation being necessary, on account of its almost absolute purity, The analysis of the rock show, about 50 per cent silica and 80 per cent. magnesia. The deposit is owned by the Sall Mountain Asbestos Co. of Saute, White county, Ga. The company manufactures the asbestos into lagging for locomotives, cover- ings for boilers and steam pipes, insulating materials for refrigerators and cold storage cars, coaches and sleeping cars and material for deafen- ing floors. It is also made into material for fire proofing and insulating partitions. The sales agency of the Sall Mountain Asbestos Co. is in the hands of Bruner, Sprague & Co., 1027 Manhatten building, Chicago. Further information regarding the asbestos can be obtained from the sales agency. On July 25 the Penberthy Injector Co. of Detroit will celebrate the event of the manufacture and sale of 100,000 Penberthy injectors during a period of ten years, extending from June 5, 1886, to May 12, 1896. An excursion will be given on the Detroit and St. Clair rivers. Friends and customers of the company, as well as employes, are being invited to join in the festivities. The Blue Book of American Shipping answers questions that arise daily in every vessel agent or owner's office. If the book is not satis- factory it costs nothing, as the $5 will be returned. Order at once, No. 409 Perry-Payne building, Cleveland. The I. 0.0. F. excursion rates to Buffalo via Nickel Plate road will be a fare anda third. Tickets areon sale Aug. 4,5 and 6, 203-July 31 ar