NO. 3. ON “ PRIMING” IN STEAM BOILERS.x The economy in fuel realized by the use of tubular boilyrs in comparison with non-tubular, is in the ratio of 1-85 to; but this advantage is often more than neutralized by the greater liability of the first to incrustation and to priming, especially in the case of vertical boilers. Priming is the result of violent ebullition in boilers with restricted water ways, where the freecirculationis impeded and is made manifest by irregular or intermittent action and by large quantities of water being carried off in mechanical i suspension by the steam produced. The waste of fuel caused by priming is not readily determined. In many cases where nine pounds of water are fed into a boiler and supposed to be converted into steam, not more than five are really thus converted, and the remainder, or hot water, is carried off as such in admixture with the i steam. The loss in the above case may be calculated as j follows: Supposing the pressure in the boiler to be 90 pounds 1br square inch, the temperature will be 320 Fah., and liy Rrg- naults formula (320—32) X -305 1123-7, we find 1211-54 to be the total number of units of heat contained in one pound. If the feed water has been introduced at 60 Fah., then the amount of heat derived from the fuel would be 1211-54— I (60—32) = 118354 units of heat for every pound of working i steam generated. Five pounds of steam will contain 5917-70 units, and the water at boiling point (320 Fah.) will contain 320—32 = 288 units per pound, or 1152 units for the 4 pounds, this being equivalent to a net loss of 19-47 per cent of the fuel practi-tically consumed. It is found difficult to maintain the pressure in cases of priming and the vacuum is seriously injured by it, so that this occurrence must always be regarded as most undesirable and as a source of pecuniary loss. Priming being most frequently due to defective boiler coii-struction, can generally be remedied only by making rational changes in the interior distribution of parts, or by the substl- tution of one system of boiler for another. A less generally understood method of counteracting the injurious effects of water in steam is by superheating. This may be done either by direct action on the whole of the steam generated, or by the admixture of a certain determined quan-i tity of superheated steam just sufficient to cause the evaporation of the suspended water and its conversion into working steam of the desired tension. The calculation of this quantity and of the temperature to which it will have to be raised -i pends on many and various causes. Knowing the quantity of fee water contained in a given weight of steam, it will always be easy to determine the bet superheating temperature necessary to be applied to any given number of pounds of steam in order to convert wet into dry, or in other words, to convert suspended water into good working- steam of the requisite tension. For this pur pose proceed as follows: Subtract the total number of units of heat (b) contained in the mixture of steam and water, from the computed total o units (a) which would be contained in the same weight of working steam of the required tension; divide the result b; the number of pounds of steam (c) which it is desired to superheat; multiply this quotient by the specific heat of steam 0-847 and add the number of degrees (d) of Fahrenheit thermometer corresponding to the given tension. This last addition furnishes the theoretical superheating temperature (a) needed, but is practically too low as no allowance has been made for losses. By our formula we would have a—h c Whenever the superheating can be realized by means of the waste heat of the furnace, a very material gain in the amount of fuel consumed will always be noticeable; when, however, (as is often done) the superheating is effected bj the combustion of an extra quantity of coal the benefit derived from it is comparatively inconsiderable. Some other day we may again refer to the practical advantages and disadvantages, of superheated steam, and to the subject of superheaters in general and their various applications. This is an interesting subject which the experiments of Wethered, Partridge, Pilgrim, Lafond, and many others have failed to completely elucidate in its multitudinous aspects. The practical conclusion derived from the above considerations is: If your boiler primes, either swap it off for another, or superheat your steam moderately, but beware of anti-priming doctors and their remedies. CULTIVATION OP SUGAR IN LOUISIANA.—A correspondent from Louisiana writes us that the great want of that State is labor. Notwithstanding the planters are making use of all the labor-saving machinery which they can get, they still lack laborers. Farm hands get from $14 to $30 per month -with board; carpenters $75 to $125, blacksmiths from $45 to $60. He says if that State can get the labor, it alone will produce, all the sugar needed for home consumption. He invites northern people toturn their attention to the opportunities for profitable investment now offering there, and says there arc land and work for all who will come. LAEGE quantities of celestine, sulphate of strontia, a mineral of a beautiful delicate blue color, well known to mineral ogists, have been found at Mok-attam in Egypt, in limestone beds. 148 Improvement in Rotary Blowers for Furnaces, Forges, etc Experience has proved that in the case of large foumleries and forging establishments, where a strong, steady, and well sustained blast is required, great care is necessary in constructing blowers. Delays caused by breaking and tlio consequent repairs are not infrequently more expensive than the original cost of the blower. The machine should, therefore, be made of the best material; lubrication should be deemed of the first importance; parts liable to the greatest wear should be furnished in duplicates easily put in place, and the workmanship should be of the best quality Such, it is claimed, are the qualifications of the blower shown in the accompanying engravings, a claim that is supported by such men as the engineers of the Charlestown, Mass., Navy Yard; Wm. Mason, the well-known inventor and manufacturer, Taunton, Mass.; Pratt, Whitney & Co., the celebrated tool builders, Hartford, Conn.; 0. Ames & Sons, North Easton, Mass.; and by the Rath-bone Stove Works, Albany, N. Y.; National Foundery Pipe Works, Pittsburgh, Pa.; Hink ley & Williams works, Boston, Mass; and a hundred others in all parts of this country and Great Britain,and in Continental Europe. In short, the Sturtevant blower is too generally known and appreciated to require special commendation. The piston blower or blast engine is complicated and expensive to keep in order, and neither it, nor the ordinary fan blower, gives generally more than one pound pressure to the square inch, while this blower yields one and a half pounds, and is noiseless, perfectly balanced, and not liable to get out of order. The case of the blower is composed of a series of circular arched sections, forming the periphery, and secured to the side plates by screws, these side plates being braced on on the outside by radial ribs to render impossible any expansion or springing by the pressure of air within. A central aperture is left in these side plate, as ordinarily, which is surrounded by a dovetailed concentric groove for receiving the bolt heads by which the tripod supports to the bearings of the shaft are held. This enables the arms of the tripod or brackets to be adjusted to accommodate the direction of the belt. About this circle or annulus, is formed a scroll-shaped recess intended to diminish resistance. The fan or wheel is made with curved floats, to revolve in the direction of their convexity, and of the form of the cross section of a frustrum of a cone. They are connected to curved annuli, or plates, fixed to two yoked wheels, one on either side the fan, intended to form a partition between the air in the case and that in the wheel and to direct the air properly out of the periphery of the wheel. The large air space around the periphery of the wheel affords room for the free discharge of the air from the wheel and prevents noise, which is generally occasioned in common fan blowers by the wheel running in too close a proximity to the inside of the case. Each of the radial arms running from thewheel shaft is fastened to the base of one float, the apex of which is connected to the next arm by a stay or rod, thus holding the floats or blades in place, and preventing longitudinal expansion under high speeds. The shaft is supported in tubular bearings, sustained in the projecting brackets by means of ball joints, by which the bearings are enabled to accommodate themselves to the shaft while in revolution. The shaft is inclosed in a tubular bushing set up by a screw at its end to adjust the fan transversely. This may be removed to replace the bearing when too much worn. This bushing is bored or cored longitudinally, sufficiently far to meet radial openings opening into an annular chamber, which is fed with oil by the oil cup and wick seen in the enlarged vertical section of bearing and oiler. Around the bearing is a recess in the box which is stuffed with sponge, designed to absorb a portion of the oil that passes from the reservoir at the smaller or outer end of the journal to the larger or inner end. This is sufficient to lubricate the bearing, if, from inattention, the oil cup or reservoir is not kept properly supplied. At the inner extremity of the journal an annular recess in the box receives the superfluous oil and conducts it by a pipe or passage to a receiver un-[ der the oiler, from whence it may be drawn off and saved, and prevented from reaching the inside of the case and fouling it, an annoyance that greatly impedes the velocity of the blast in ordinary blowers. This result is further secured by the driv- ing pulley, the web of which is solid and effectually prevents the passage of the oil to the inside of the case. Where the : blower case is seated on a bed, as in the engraving, an adjust- ing screw is attached by which it may be moved to take up the belt. The eduction pipe of the case extends into a stationary flange or collar supported by a standard erected on the base. The pipe for the conveyance of the air to the furnace or forge is fitted upon tho collar, and thus the movement of the blower case may bo made without disturbing its position. These blowers are used extensively for producing a draft to carry away the dust, hot air, and impure odors from manufactories of various kinds. Patented in the United States, England, France, Belgium, and other foreign countries; the home patents being dated Oct. 29, 1867, and Feb. 2, 1869. All orders should be addressed to B. F. Sturtevant, patentee and sole manufacturer, 72 Sudbury St., Boston, Mass. Lenses versus Drills Mr. John Thompson, of Philadelphia, writes us in regard to the substitution of lenses for drills in perforating rock for blasting and other purposes. He thinks them specially applicable to the Darien excavations for the proposed ship canal, ae that locality, being tropical, he thinks,affords greater facilities than more northern localities for the object in view. We have not room for the dissertation upon burning glasses, by which he ingeniously supports his novel proposition, but recommend it to the consideration of those who are interested in the great work alluded to. Could not the same principle be applied to fusing the gold in quartz rock, so that it would run out of a hole and be caught in buckets like maple sap ? If any of our readers try the experiment, we shall be pleased to learn the result. A Natural Mechanic From the Rev. Chester Briggs, Columbus, Ohio, we have received a communication inclosing a photograph, the facts of which may interest our readers. It seems that a colored boy about 18 years old, and a slave from birth until liberated by the late war, has built, during his evenings, after laboring daily as a woodchopper, a model of a loco motive and tender combined, about four feet in length and well proportioned. Tho model is of wood, built by the aid of a few tools— ax, saw,auger, and knife—in the woods,without patterns, drawings, or any instruction whatever. Judging from the photograph, the expression of favorable opinion as to workmanship, and the natural qualifications of the young man, given by experienced mechanics who have examined the model, is fully sustained. The machine is a working model, although, of course,without steam, and is per-: fectly proportioned in every part. Mr. Briggs desires to interest liberal men in the case, and procure for this representative of an oppressed race, an education which shall fit him for the sphere for which he seems naturally designed. We commend the case to the lovers of the race. Communications may, we presume, be addressed to Rev. Chester Briggs, Columbus, Ohio. A NEW ANIMAI., to which Prof.Huxley, of England,has given the name of Bathybius.has been discovered during the operations of laying recent submarine telegraph cables, and other submarine engineering operations. It is gelatinous in consistence, and seems to reside at the bottom of the Atlantic,extending over miles of surface, yet a continuous living mass. It is believed by physiologists to be a gigantic protozoan, and the lowest form of animal life to be found upon our globe. It is also supposed to possess the power of drawing subsistence direct from the mineral world like plants. It is, no doubt, destined, in its classification become a bone of contention among naturalists, occupying, as it does, the boundary line between the vegetable and animal world. We may, therefore, expect the Bathybius to occupy a conspicuous place in zoological literature from this time forth. 149 A New Single-Wheel Velocipede The single-wheel velocipede, which we noticed as an imaginary propeller in our issue of February 13, has received a palpable body and a local habitation and name by the enterprise of the inventor of the machine herewith represented. Queer and odd as may be the appearance of the concern, Mr. Hemmings says that his son of thirteen years old propels one of these machines of five feet diameter at a pace that keeps up with good roadsters and does not allow them to pass him. As will be seen by the engraving, the grayhound is not able to keep up with the rider of this novel velocipede, but his master is compelled to reverse his motion and throw the driving friction wheel back of the center of gravity. The main wheel has a double rim, or has two concentric rims, the inner face of the inner one having a projecting lip for keeping the friction rollers and the friction driver in place, each of these being correspondingly grooved on their peripheries. The frame on which the rider sits sustains these frictions wheels in double parallel arms, on the iront one of which is mounted a double pulley, with belts passing to small pulleys on the axis of the driving wheel. This double wheel is driven, as seen, by cranks turned by the hands. The friction of the lower wheel on the surface of the innerrimof the main wheel is the immediate means of propulsion. A small binding wheel, seen between the riders legs, serves to keep the bands or belts tight. The steering is effected either by inclining the body to one side or the other, or by the foot impinging on the ground, the stirrups being hung low for this purpose. By throwing the weight on these stirrups, the binding wheel may be brought more powerfully down on the belts. Over the riders head is an awning, and there is also ashield in front of his body to keep the clothes from being soiled by mud and wet. When going forward, the driving wheel is kept slightly forward of the center of gravity by the position of the rider. By this means the power exerted is comparatively small. A patent for this unique vehicle is now pending through the Scientific American Patent Agency. Further particulars may be obtained by addressing Richard C. Hemmings, at 294. Wallace street, New Haven, Conn.
This article was originally published with the title "“Waste” and “Economy” of Fuel" in Scientific American 20, 10, 147-149 (March 1869)