Kingdom.] KAIL WAY AND MARINE MECHANISM. 221
North Areas A. B. 10 to 34 ; 0. D. E. 1 to 10, & 19 to 33 ; F. 1 to 32 ; Q-. H. 1 to 13, & 19 to 26.
which the steam has a power superior to the resistingforce will advance by acceleration, but the fixed arm notpartaking of the increased speed, the space between thesecond roller and the arm of the boss will be increased,and by the action of the rollers the spring will be com-pressed ; that period being passed, and the impellingpower falling below the resisting power, the latter willprevail, and bring back the wheel again to the place, withrespect’to the mean place, from which it started. Now,when the fly-wheel advances, by its oscillating move-ments, it will leave the arm of the boss behind, and thestrap connecting it with the second roller, will occasionthe roller to move on its axis, which will result in thedrawing up of the bolt, and compressing the spring;. andthe reverse will happen when, through its oscillations,the fly-wheel loses speed; and thus the fly-wheel will goon oscillating twice in every revolution, the oscillationsplaying smoothly and harmlessly upon the spring.
Now, if both the rollers be cylinders of the same dia-meter, the reactive force of the compressed spring, andthe force dragging the led arm and main shaft, will beequal; and as constant variations will take place in thecompression of the spring, an equal variation will occurin the force leading the arm; and although, to a greatextent, an equalization will have been effected, theproblem of the conversion of a fluctuating force into aconstant force has, as yet, received no solution.
But the rollers are not both cylinders; the secondroller is bounded by an irregular curve, a part of which—called the isodynamic curve—is so formed that, in itsrotary motion, the lever of resistance within it, throughwhich, and the second strap, the fixed arm acts againstthe force of the spring, shall become lengthened as thatforce increases, the curve offering in every position a leverof resistance proportional to the force of the spring.With this final appliance, a perfect uniformity of force isobtained, and the problem proposed is solved.
In order to explain the actual working of a specificsteam engine with these appliances, suppose the modelextended, in all its parts, linearly in the ratio of 3 to 10 :the fly-wheel will then be of 10 feet diameter, and willhave 1,500 pounds weight in its rim. The engine to be of10-horse power, clear of all loss by friction or otherwise,in its own parts; strokes, 40 per minute. The steammay be applied to the piston at any amount of pressure,and be worked expansively, or not. The springs, as inthe model, to be 3 : coiled of steel wire, £ inch in dia-meter ; the coils to measure 2J inches in diameter to themiddle of the wires; the space between the coils, whenthe spring is relaxed, to be equal to the diameter of thewires; the number of coils, 70; its whole length, whenuncompressed, consequently, will be 35 inches. Such aspring will suffer compression of 1-17 inch for every10 pounds of compressive force. It is proposed that eachspring shall be confined between the studs, with a forceof 40 pounds, by which the length will be reduced to30 • 32 inches: this compression is not necessary to itsproper action, but it keeps the length of the spring withinconvenient compass. The breadth of the rim to be7 inches ; therefore, the circumference of a circle, at themiddle of the rim, will be 29'6 feet; and the speed, atthis place, will be 1,184 feet per minute. The meanforce communicated, at any point in this circumference,will be equal to 279 pounds. Let this force be trans-mitted, through 3 springs to the arms, then we shallhave a force of 93 pounds applied to each arm.
A wheel thus circumstanced will have an oscillatingmotion of 1*26 inch from its mean place, and the mea-sure, between the extremes of its oscillations, will be2 • 52 inches; and as the axis of the rollers is placed inthis circle, the variations in the compression of eachspring will be of the same measure (2 • 52 inches). _
Now, since the compression of the spring is 1*17inches, with a force of 10 pounds, a compression of 2- 52inches will be the exponent of a force of 21 • 54 pounds,and 21 • 54 pounds will be the variation of force commu-nicated from the fly-wheel to the fixed arm; and since themean force, applied to one arm, is 93 pounds, the maxi-mum force, when the fly-wheel is at the extreme of its
advance, will be 103-77 pounds, and the minimum, inthe contrary position, 82-23 pounds; and this variationis so moderate, that, for most of the purposes to whichsteam-engines are applied, it would scarcely have anyappreciable disturbing effect.
For the final correction of this remainder, the isody-namic curve must have a length equal to the extent ofthe action of the springs, or the wheel’s oscillations,2 ■ 52 inches; and the radius of resistance of the mini-mum force must be to that of the maximum, as thesmallest force of the spring is to the greatest that is, as82-23 to 103-77.
With respect to the minimum weight of fly-wheel thatmay suffice in a given engine, under these arrangements,it must depend upon the range of action that can beobtained in practicable springs. In the case assumed,the wheel is supposed to have a rim of 1,500 pounds; ifhalf that weight had been taken, the length of the arc ofoscillation would have been doubled; and if we couldemploy springs in which the range of compression wouldbe twice as great as in those proposed, when acted on bythe same force, we should have a regulating power of thesame efficiency; and if we desire to perfect the uni-formity of force, we might do so by employing an isody-namic curve of twice the length, keeping the radii whichconstitute the levers of resistance of the length proposedin the first case, and the action of the engine would bethe same.
This invention claims not only to improve, but to per-fect the action of the Reciprocating Steam Engine ; it issimple, of easy and inexpensive construction, and butlittle liable to go out of repair. A proper method oftrying the action of the model is, to stand at the right-hand side, holding one of the arms of the fly-wheel in theleft hand; then applying the palm of the right hand tothe fixed arm in advance, and forcing the arms apart.It will require a force of about 40 pounds to bring thesprings into action.
7 6 Craddock, Thomas, Manelagh Works, Pimlico —Inventor and Manufacturer.
Patent high-pressure, expansive, and condensing steam-engine, with tubular boiler and regulating damper. Thenovelty consists in the mode of condensing the steam andobtaining the vacuum without cold water, in the mode offixing the cylinders of the engine at an angle, so that thetwo connecting-rods take hold of the same crank-pin, andin the construction of the valves, the expansive gear,’ andthe regulating damper.
82 Morrell, G., 149 Meet Street —Inventor.
Patent rotatory engine, fitted as a steam-engine. Itmay also be used as a pumping and forcing-engine, or asa blowing apparatus for blast-furnaces. The following-cut represents the front elevation of the engine, and
Front Elevation. Section.