Maritime History of the Great Lakes

Marine Record (Cleveland, OH), August 15, 1895, p. 10

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10 THE MARINE RECORD. pe waJwJwZ_a_auuooeor SSS ’ IN THE ENGINE ROOM. _ WATER-TUBE BOILERS. _ (Extracts froma paper read by M, J, A, Normand, at the thirty-sixth session of the Institution of Naval Architects, Paris, June 13, 1895.) The intensity of firing in water-tube boilers is limited by the formation of ‘‘steam chambers’’ or stationary, steam, in the heating tubes, and by the strains due to the expansion of these tubes. The temperature of a heating surface, behind which only steam exists, rises to such an extent that it rapidly becomes oxydized, externally by the hot gases, which are always mixed with oxygen, and internally by the steam. Moreover, the strength of the metal when thus over-heated is reduced so as to.render rupture probable. The formation of. those ‘‘steam chambers’’ may be prevented by the following means: (2) The direction of the tubes, especially in their lower and more heated part, must be as_ vertical as possible. (4) The circulation must be very active. This is nearly self-evident. The greater the circulation the cooler are the tubes. ‘Itis well known, moreover, how favorable is the agitation of water to the transmission of heat. Laboratory experiments have shown that the co-efficient of transmission varies from one to five, according as the motion of water is #/ or very great. Increase in the economic duty of the boiler means easier firing. (c) The proportion of length to diameter in the heat- ing tubes ought not to be too.large. Within the ordinary limits of the ratio of length to diameter the resistance to the motion of water is nearly proportional to this ratio. The circulation of water, so essential to the good working of a boiler, is reduced as the resistance in- creases. Moreover, all the steam generated in the in- ferior part of the tube must pass through the upper end. The longer the tube the smaller the density of the fluid in the upper part, and the greater the chances of its being burnt. (d) The section of the outside down-take or water-re- turn tubes, from the upper to the lower reservoirs, ought to be of large proportions. When the boiler is at work, the pressure in the inferior reservoir is always less than in the upper one. Should it be otherwise, the water would not flow down by the return tubes. It is most probable that the steam generated in the heating tubes (or the air mixed with the feed) produces the circulating of water by impulse only.” This force of impulse is so great that when the tube is vertical the ascending mo- tion of the fluid may be estimated by applying the theory of communicating vessels, according to the difference between the mean density of the heterogeneous fluid in the heating tube and that of the water in the return tubes, due allowance being made, of course, for friction. When the heating tube is more or less inclined, the adherence of bubbles to the inside surface is such that this mode of reckoning would certainly give a much higher speed than is actually the case, the error being | greater as the inclination of the tube approaches the ‘horizontal. This affords another proof of the import- ance of verticality in heating tubes. Should the soundness of these views be questioned, one thing, however, is indisputakle—the rise of water and steam in the heating tubes produces a difference of pressure between the upper and lower reservoirs, and this difference reduces the intensity of the circulation from which it is a consequence. Accordingly, it is most important to lessen this differ- ence in giving to the return tubes the greatest possible section. _ The second cause which limits the intensity of firing is the strains due to the expansion of the heating tubes. Several well-known arrangements prevent these strains. For instance, that of the Belleville boilers, the use of Field tubes, as in the Collett-Niclausse boilers, and es- pecially the adoption of heating tubes sufficiently long and sufficiently curved (both conditions are necessary) for preventing oblique strains on the junction with the tube plates. Itis also most important that no joints or riveting should be allowed in the actual vicinity of the furnace. Most of the principles laid down in this paper may ap- pear to be so simple as to render their statement useless. °* Copper would last much longer than steel, but itis very dangerous, as, in case of bursting, the tube opens out fully, allowing the hot water and steam to escape through double the section of the tube, Ordinary brass becomes brittle and: weak when overheated, With mild steel the section of the orifice is generally small, Security against personal injuries surpasses at all other considerations in importance, ‘invention of Mr. It is not so if we consider how very few of the different types of water-tube boilers are designed in accordance with all of them. However, my object is not to criticise any of these types, when not intended for intense firing, although the best boilers for intense firing are also generally the best for slow work. Many water-tube boilers are now making steam with tubes nearly horizontal, very low fire-boxes, great section of passage and short length of travel. Each can boast of particnlar advantages which cannot be disputed. But the conditions imposed for boilers become more and more severe. In order to save weights, the com- bustion of fuel per square foot of grate increases every day; 20 pounds is no longer sufficient; twice, perhaps three times as much will’soon be expected for the most powérful engines. A good design will give the owner, the engineer, or the navy that adopts it a great advan- tage. Itis worth while to examine how it will be pos- sible to meet impending exigencies. The new design of automatic marine fog signal, the F. H. Berry, of London, has been fitted to the British India Steam Navigation Co.’s steamship, the Dunera. The object of the apparatus is to give automatically, at the regular interval required by law in case of fog, the whistle or bell signals. On the bridge ‘of the vessel is mounted a switch, by turning which the officer in charge can divert an electric cur- rent to either the whistle or the ship’s bell, the latter, of course, being sounded if the shipis at anchor, and the former when she is under way. The proper inter- val between the sounds is obtained by clock-work placed in the chart-house or some other convenient position. The current is generated by means of bat- teries, the clock-work completing the circuit at the nec- essary intervals, and in this way electrical energy is obtained for either striking the bell or opening the valve of the whistle. At the same time that the whistle is blown or the bell sounded a pen is brought into con- tact with a continuous band of paper, which is marked with divisions. As the paper is wound off at a uniform speed by the clock-work an autographic record is ob- tained showing when the fog signals, by bell or whistle, are sounded. Fata rr 6 SAILS ON CHINESE CRAFT. The hack-artist of the world at large treats their sails —the most picturesque bits of China—as if they were Venetian blinds, made of big bamboo slats backed by canvas. That is not at all how they look. The bamboo slats are in them, but they are very small, and.are only seen when near at hand. Otherwise I do not think it would be easy to say anything of them that is not true —they are so dissithilar and varied and peculiar. One ‘towers like a great white steeple or a cloud above houses, trees and everything. The next may be made of awoman’s apron ora little mat. One is composed of a single blue shirt, and the next is a crazy quilt of a hundred gorgeous flags. In a day’s journey we saw white ones, red ones, black ones, and others that were splotched, patched, tattered or rent. We saw sails made of matting, madeof old coats, made of trousers and of banners. We saw sails with prayers painted pon them, others with mottoes, others with pictures, and what may be called heraldic devices... Most of them were mere parallelograms of cotton, but some were like schooner sails at home, and some were lateen-shaped. There is no rule as to the number of sails a boat may carry, and one often sees five spread on the: larger junks, upon three regular masts and two smaller ones fastened to the vessel’s sides, one forward and one aft. A great part of the din that beats upon the air of China comes of the raising and lowering of these masts and sails, for on all except the sea-going craft the masts are hinged, and are forever being pulled up or let down. To do this work the Chinese crews are bunched together on each deck, where ‘they shout with every output of strength.—_From ‘‘Eyvery-day Scenes in China,’’» by Julian Ralph, in Harper’s Magazine for August. ca HYDROGRAPHIC CHARTS Of Lake Superior, Lake Huron, Lake Erie, Lake Onta- rio, Georgian Bay and Detroit River, for sale at the office of "THE MarINE. RECORD, 144 Superior street, Cleveland, O. Price, 50 and 75 cents each. 2 “sale or otherwise. NAVAL MILITIA ORGANIZATIONS, The naval militia organizations, as bred and created largely in a yachting atmosphere and now existing in 13 states, with a present complement of 226 officers and 2,706 men, are the first auxilidries to be considered. The existing naval militia is primarily a state organi- zation, dependent largely upon local and state support, and enrolled as part of the National Guard. It is nota true naval reserve which should owe allegiance only to the general government and be subject solely to the naval regulations governing the general service. While subject, however, to state control, the naval militia is kept in constant touch with the regular estab- lishment by receiving, for arms and equipments, in each state, a portion of the $25,000 annually appropri- ated for its encouragement by Congress, and distributed by the department under such rules as are deemed wisest and best for thé object to be accomplished. Con- gress has also authorized by law the loan of unused ships and other property to states having organized and — equipped naval militia. The ships so loaned are those out of commission and unsuited for regular naval ser- vice. The greatest difficulty now encountered is to find a sufficient number of such vessels to meet the demand, The discarded wooden ships of the old navy make most excellent inshore armories for these organizations, but, unfortunately, these have nearly all been disposed of by Following the spirit; as well as the letter of the law, the department bas endeavored to give to these organizations every possible encourage- ment, keeping them in touch with the navy by advice on all professional subjects, inspection by officers when- ever desired, issuing printed documents for their in- struction, opening up all sources of professional inform- ation, and giving them each summer an opportunity for a short cruise on some of the ships in the regular service, where, in addition to being taught somewhat of the manifold duties of a man-of-warsinan. they are enabled to practice firing the great guns at a target from the moving ship. They are also allowed to draw at first cost arms and equipments from the portion of the national allowance allotted totheir state. Asa re- sult, in some of the states, the naval militia is the best armed mllitary body in the state, having rapid fire guns of the very latest pattern, magazine rifles, and good serviceable navy revolvers. All this, however, would be of little avail without intelligent, persistent and enthusiastic individual effort and the support of the state to whose forces they belong. Itis but right that it should be said here that some of the states have been most liberal and progressing in encouraging and aiding this new arm of defense. Inu the states where the or- ganization is best and most efficient these results have been secured by great labor, patienceand tact. There were and are sources of opposition calling forth deter- ~ mination and sound judgment.—From an article by the Hon. Wm. McAdoo, Assistant Secretary of the Navy, in North American Review for August. ED ee er : TRADE NOTES. A daintily illustrated little ‘advertising booklet has been issued by the Harrisburg (Pa.) Foundry and Ma- chine Works. The Davis-Farrar Co., of Erie, Pa., (Humboldt Iron Works) are sending out a neat pamphlet containing illustrations of their pumps and suction dredges. The American line steamship St. Louis, will, it is said, on the completion of her sister ship, the St. Paul, be taken to the Cramp’s shipyard in Philadelphia, where she will be fitted with larger funnels, in order that the ship’s full power may be attained. The Morris Machine Works, successors to Heald, Sisco & Co., and Heald & Morris, Baldwinsville, N. Y., have just issued a circular descriptive of the Heald and Sisco patents in centrifugal pumping machinery. ‘This firm has established a New York office at No. 39 and 41 Cortlandt street, with Hungerford Bros. & Co. . The American Ship Windlass Co. has just received an order for two Manton towing machines from the Phila- delphia & Reading Railroad Co, on whose tug Lebanon the machine has been used for six months. The man- agement say that in addition to the saving in hawsers, the energy is so equalized by the use of this machine that they can tow three barges with it cheaper than two without it. The manufacturers have inquiries from the lakes, whereby three or four additional machines will be called for within the next thirty days. iat

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