Page images
PDF
EPUB

a degree of saltness from which no practical evils can result, however long the boiling be continued.' The proposition, therefore, is to effect a continued changing and refreshing of the water in the boiler, by constantly drawing out a quantity of the supersaturated water or brine, and introducing other water to supply the place of that so withdrawn, as well as that which had been evaporated, by which means the water in the boiler can never exceed a certain degree of saturation, proportionate to the quantity so withdrawn.

409. The method proposed to effect this object is by the employment of meters, of any kind, that will regulate and adjust the quantity withdrawn to the quantity evaporated or driven off in the form of steam. No drawings are exhibited in the specification, it being considered that a general description of the method and kind of apparatus to be employed will be sufficient to enable any person to construct the necessary machinery. The meter recommended to be used is a small pump with a loaded discharge valve, worked by the engine, and so proportioned as to draw from the lowest part of the boiler the quantity determined upon.' 410. If, for instance, twenty-five per cent., or one quarter of the total evaporation, be the quantity withdrawn, it will be equal to one-fifth the quantity of common salt water driven into the boiler to keep up the supply. Thus, as sea water contains about 0-32 parts of salt, the water of the boiler will slowly but ultimately attain a degree of saltness equal to 5.32 or 4.32 parts more than sea water. After this every stroke of the engine will take as much salt out of the boiler by the pump as is left in the boiler by the steam used in the cylinder for that stroke.'

.

411. The engine working quick or slow, the quantity withdrawn bears the same proportion to the quantity left in; and, however long the engine may be worked, the water can never be more salt; thus avoiding the evils and inconveniences to which steam vessels have been hitherto subject on long voyages, in being obliged to stop to empty and refill the boilers every fifty or sixty hours, or incur the risk of severe injury to the boilers, from the deposition of salt within them, and a very great sacrifice of fuel the latter part of the fifty or sixty hours, when the water, from the quantity of salt it contains, is very unfit for raising steam.'

412. The second part of the invention is the means to be employed for arresting the heat contained in the rejected water, and returning that heat into the boilers. This is to be effected by running the hot brine into a vessel, and passing the supply water through a system of pipes or tubes of extended surfaces, immersed in the vessel containing the hot brine, and surrounded by it, in the same way as refrigerators are made to act upon worts. By these means the heat contained in the water or brine, expelled from the boiler, will be principally absorbed by the supply water, as it proceeds into the boiler, thus compensating in a great degree for the loss of heat which would otherwise be sustained, by reroving a portion of the hot water, and introducing other which is cold.

413. Mr. Taylor's improvements have for their

object the prevention of unequal friction in the working of pistons that move in steam cylinders, either in horizontal or inclined positions. This object is proposed to be effected by passing the piston-rod through both ends of the cylinder, and by keeping the rod in a state of tension, by means of weights acting at each end of the rod.

414. In order to render this more evident, let it be supposed that the working cylinder of a steam engine is fixed in a horizontal position upon brick work, and that the rod of the piston is extended in a straight line, and passed through both ends of the cylinder, the apertures being properly packed, and the rods running upon anti-friction rollers in frames, for the purpose. of keeping its action parallel; and that at the extremities of the piston-rod, bridles or sweep rods are attached, which are connected to double or right angled levers, these levers being for the purpose of giving the up and down motion to pump rods below the base of the engine.

415. It will now be perceived that in an engine so constructed, if the piston be made to reciprocate in the cylinder by the alternate expansion and exhaustion of the steam, that the long rod will move to and from, and work both the right angle double levers, raising the pump-rod at one end and depressing it at the other, and vice versa. It will also be seen that under these circumstances the piston-rod will be supported in all parts of its movement, and prevented from rubbing unequally; and this will be further aided, and the rod prevented from binding, by the tension produced by the weight of the levers and pump rods at the extremities.

416. In this way several cylinders may be connected together, and their powers made to act simultaneously upon one point, their rods being in the manner above described connected by bridles or sweep rods to the right angle levers below. This contrivance is applicable to engines that are worked either by expansive steam alone, or by exhaustion, or by the principles of expansion and exhaustion combined. The force of the engine, or combined engines, constructed as above, may be directed to one end of the piston-rod, by placing a weight upon one of the levers, 'equal to half the power of the engine and weight of the pump rod; this weight will be raised by half the power of the engine in one direction, and its gravity, added to the power of the engine in the other direction, will concentrate the total power on the rod.'

417. The patentee states his claim for novelty of invention to consist in the mode above described, of preventing the unequal friction of pistons working in cylinders either in a horizontal or inclined position, by passing the pistonrods through both ends of the cylinders, and by keeping such rods in a state of tension by means of weights or loads acting on each end of such piston-rod; and the modes, above described, of combining engines with cylinders placed in a horizontal or inclined position, so that they will work simultaneously, by which means the power of several such engines may be concentrated upon one point.'

418. Sir William Congreve obtained two patents for improvements in the rotatory engine.

The first of these consisted principally in the employment of bucket wheels, or endless chains with inverted buckets, against which the expansive force of the steam exerted itself, in an upward direction; and, by raising the buckets, in a manner exactly the reverse of their descent in a water-wheel, the motive force was given to the engine and other machinery.

419. The second specification states, I work all the various constructions of rotary steam engines, as well as those on the reciprocating principle embraced in my patent of 19th October, 1818, in a medium of fluid (or melted) metal, or alloy, in lieu of water.' By this substitution of fluid metal instead of water, an additional power is said to be obtained in engines of any given dimension, and that in proportion to the increased density of the medium so employed; hence the magnitude of an engine of any required power will be reduced, which will render it more compact, and less expensive in constructing.

420. It is further proposed to increase the power of any engine of given dimensions, by causing the temperature of the surrounding medium, of melted metal or alloy, to be kept at a higher temperature than that of boiling water; 'by which means the energy of the steam may be made equal to that of a high pressure engine, though the surface of the medium be open to the air: while, on the other hand, by working with the medium in a close vessel, and applying a condenser to exhaust the steam as it rises to the surface of the medium, a still further expansion of the steam, and consequent increase of power, may be obtained with a given temperature and given means, by thus removing the incumbent pressure of the atmosphere.'

421. The importance of these new principles will at once be understood by those who are versed in these matters, as they will perceive (taking one instance only, by way of example) that, by working the simple rotatory engine of my invention, formed by the immersion of a common hydraulic wheel (as described in the first case in the specification of my above-mentioned patent) in a medium, the specific gravity of which to water shall be as ten to one, a small wheel of two feet in diameter in such a medium will be impelled by steam of the same pressure as a wheel of twenty feet in diameter working in boiling water and, consequently, that whereas, to obtain the same pressure as that of the steam of a common condensing engine, from steam working on this principle, in a medium of boiling water, would require a machine of very large dimensions, this same effect may be produced in a heavier medium by a machine of very moderate dimensions indeed.'

422. By working the steam in a medium of high temperature, the size of the boiler may be reduced, and a considerable saving of fuel effected; for the volume of steam from a small boiler will be very rapidly increased by these means to the extent of three or four-fold, without the medium being raised to any very high temperature; and a still more rapid evolution of steam would take place by raising the temperature of the metallic medium to such a height as

it is readily susceptible of; nor would there be found any difficulty in keeping the temperature of the fluid metal so raised to perform its operations.

423. Indeed, by carrying these principles to a greater extent, the necessity of a boiler may altogether be obviated; and the steam produced at once, by the injection of small quantities of boiling water, from time to time, into a small inverted receiver, in the heated medium; whence it would be carried to the proper part of the revolving wheel, or bucket, or other receiver in which it is to act, according to the particular construction of the engine: and in which inverted receiver the steam, from the rapidity of its generation, must be created at a much less expense of fuel than in any of the ordinary processes of the boiler; wherein, as the generation is comparatively so much slower, there is consequently so much more time even for the loss of heat by radiation. In fact, whether this heated medium operates by increasing the volume of steam ready formed in a separate boiler, or in the immediate generation of it without a separate boiler, the increased volume in one case, and the entire generation in the other, are effected in the very same moment that the steam produced is brought into action; and consequently without allowing any interval of time for the loss of heat.'

424. In the present state of this novel and rapid mode of producing and applying the force of steam, it is indeed impossible to say to what extent of power the effect may be carried, in proportion to the fuel consumed. It is evident, however, that so far from any possible condensation taking place in the steam, from the time of its generation to that of its action, the tendency of this mode of applying it is that of a continued accession of temperature.'

425. It is further stated that these modes of generating steam, or of increasing its volume when generated in a common boiler, is applicable to every description of steam engine. In the first case, the substitute of the boiler should be a moderately sized strong vessel, partly filled with the melted metal, into which small quantities of boiling water are to be injected at certain intervals of time; and, in the last case, the steam is merely passed through such a vessel, surrounded by the melted metal, in its way from the boiler to the engine.

426. In order to regulate the temperature of the fluid metal employed, the iron vessel in which it is heated should be surrounded by another iron vessel or jacket, filled, (when a very high temperature is desired), with oil or other such substance; by which arrangement the maximum temperature of the metallic medium will be limited to the boiling point of the surrounding fluid; and, in this case, an alloy of tin and lead, in equal parts, is proposed as a convenient medium for the above purposes; as it is not expensive, and becomes fluid at about 300° of Fahrenheit. When only a low temperature may be required, the medium should be formed by that alloy of lead and bismuth commonly called fusible metal, which becomes fluid at about 200° of Fahrenheit, the vessel in which it is contained

being immersed in boiling water. All the provisions of this patent apply also to the hydraulic wheel engines, whether the steam be made to enter into the buckets at their circumference, or through the hollow axis, and whether these buckets be open or closed ones.'

427. In Messrs. Boulton and Watt's bellcrank engine, the cylinder is supported by brackets proceeding from a cast-iron condensing cistern, and is placed over one end of it. The beam, which is formed like a right-angled triangle, has its centre of motion at the right angle, and the axis of it is supported by bearings screwed to the cistern; and, at the opposite end to that upon which the cylinder is placed, the horizontal arm of the triangle forms the working arm of the beam, to the extremity of which the power of the cylinder is applied. The connecting rod is jointed at the upper end of the perpendicular arm, and extends to the crank, which is supported in bearings screwed to the cistern at the same end at which the cylinder is placed, the centre of motion being at the same level with the top of the cistern; and, beneath the cylinder, the hypothenuse of the triangle of the beam forms a brace to strengthen it. Two of these beams are used, and are applied on opposite sides of the cistern, upon the same axis of motion, and are united together by cross rods, thus forming two connecting rods and cranks upon one axis of motion, the fly-wheel being placed at one extremity of the axis. To connect the piston-rod with the ends of the arms of the beam, or the base of the triangle, a rod is fixed across the top of the piston-rod; and, to the two ends of this, two other rods are linked, which descend to the beam, and are pointed to it at the ends. By this means the ascent and descent of the piston-rod produce a corresponding action of the beam upon its centre of motion; the upper end of the perpendicular arm moving backwards and forwards, thus by means of the connecting rods turning the cranks. The rods which descend from the bar, which is fixed across the top of the piston-rod to the ends of the beams, are so constructed as to preclude the necessity of employing the parallel motion. This engine is very compact; it requires no fixing, and the air-pump, which is placed in the middle of the cistern, is worked by two rods jointed to the horizontal arms of the beams.

428. Mr. Woolf's double cylinder-engine nearly resembles that by Mr. Hornblower, but in another apparatus, by the same ingenious individual, he proposes to apply fire to the cylinder itself, to heat the steam after it is thrown into the working cylinder; and this was to be done by a fire being placed beneath the case containing the cylinder: the space between the case and the cylinder was to be filled with oil, wax, fusible metal, or mercury. He also proposes a method of preventing the passage of any of the steam from that side of the piston which is acted upon by the steam, to the other side, which is open to the condenser. In those steam engines which act as double engines, he effects this by employing upon, or about the piston, a column of mercury, of an altitude equal to the pressure of the ston... The efficacy of this arrangement

will, he says, appear obvious, from attending to what takes place in the working of such a piston. When the piston is ascending, that is, when the steam is admitted below it, the space on its upper side being open to the condenser, the steam, endeavouring to pass up by the side of the piston, is met, and effectually prevented by the column of metal, equal or superior to it in pressure; and during the down stroke no steam can possibly pass without first forcing all the metal through.

429. In working what is called a single engine, a less considerable altitude of metal is required, because the steam always acts on the upper side of the piston; and, in this case, oil or wax will answer the purpose. But care must be taken, either in the double or single engine, when working with this piston, that the outlet which conveys the steam to the condenser shall be so situated, and of such a size, that the steam may pass freely, without forcing before it, or carrying with it, any of the metal or other substance employed, that may have passed by the piston: and at the same time providing another exit for the metal, or other substance collected at the bottom of the cylinder, to convey the same into a reservoir kept at a proper heat, whence it is to be returned to the upper side of the piston by a small pump, worked by the engine, or by some other contrivance. In order that the fluid metal used with the piston may not be oxydated, some oil or other fluid substance is always to be kept on its surface, to prevent its coming in contact with the steam: and to prevent the necessity of employing a large quantity of fluid metal, although the piston must be as thick as the depth of the column required, the diameter need be only a little less than the steam-vessel, or working cylinder, so that, in fact, the column of fluid metal forms only a thin body round the piston.

430. Having described the nature of Mr. Woolf's engine, it may now be advisable to examine the boiler by which he proposed to generate steam of sufficient elasticity for the use of the small cylinder, which requires vapor of great expansive force.

431. The boiler represented by the diagram beneath consists of a series of tubes of cast iron,

[graphic][subsumed][merged small]

small forcing-pump, as it will be evident that the column must be carried to a considerable height before its weight can so far overcome the resistance of the steam within the tube to allow of its entering by the ordinary method.

432. The plan of the boiler will better be understood by a section of the tubes represented from 1 to 8. This is furnished in the engraving beneath, and the direction of the smoke proceeding from the grate B to the flue O is shown oy the bent arrows.

433. Passing from the boiler we arrive at the steam pipes, which should be sufficiently capacious, and as short as possible, to prevent too much exposure of surface to the atmosphere. They should pass from the upper part of the boiler to the steam cylinder, in a direction greatly inclining upwards, so that any condensed water that forms in them may run back to the boiler instead of getting into the cylinder: consequently every boiler should, if possible, be set or fixed lower than its steam cylinder; and, in order the more effectually to prevent condensation, the steam pipes should be coated with haybands, or sawdust and sacking, or some bad conductor of heat, particularly if they are long and much exposed to the air.

434. In collieries, where the common steamengine is applied for drawing water from the mines, it frequently happens that, after a continuance of wet weather, the water accumulates so much as to require the engine to be worked night and day. If the boiler is supplied with water from the mines, it contains in this case a great quantity of earthy matter brought immediately from the surface, which renders the water within the boiler very muddy; and there being little time for cleaning the boiler, owing to the accumulated water in the mines, six or eight weeks elapse before this can be done. Towards the end of this period the water in the boiler is mixed with sediment to such a degree that the ordinary supply of steam cannot be raised, although the fire is increased in the furnace; the consequence of which is that the common working speed of the engine is greatly reduced. In this case it has been the constant practice of the engine-keepers in Scotland to apply a very simple remedy for increasing the quantity of steam. The substance employed is known by the name of comings, being the radicles of barley produced in the process of malting, which are separated before the malt is sent to market. About a bushel of these is thrown into the boiler; and, when the steam is again raised, an immediate effect is visible; for there is not only

a plentiful supply of steam to produce the full working speed of the engine, but an excess of it going waste at the safety-valve.

435. Mr. William Deverell has two working cylinders placed near to one another, each having a pipe of communication, with a large vessel, in which the steam, after passing from the small cylinder, is suffered to expand itself before entering the large cylinder. The pistons in the two cylinders work alternately up and down by means of valves or cocks, opening and shutting as in the common engine. Suppose the small piston has just made a stroke, and a passage is opened to the steam vessel at the end of the stroke; at first beginning to work the engine, the vessel will be full of steam of about eighteen pounds pressure, admitted from the boiler, but afterwards will only be supplied by the steam thrown into it from the small cylinder. The vessel should be about twenty times larger in capacity than the smallest working cylinder; and the larger it is the more regular will be the pressure on the great piston, which is worked by the steam coming from the steam vessel. If the steam in the boiler be of fifty-four pounds pressure per square inch, the ratio of the two working cylinders may be as 1 to 3; for then the smaller one will supply the larger with steam of about eighteen pounds pressure; the proportion, however, may be varied, though these are thought best by the patentee. The improvements here are represented to consist in the steam going from the smaller working cylinder to the steam-vessel, and then from the steamvessel to the larger working cylinder, from which it is afterwards drawn off and condensed. By these means, the engine will be very regular in its operations. Suppose the steam in the boiler is at fifty-four pounds, the small cylinder will, at the end of the stroke, be full of steam of the same or nearly the same force; and the steamvessel being full of the steam delivered to it by the former stroke of the small cylinder, at about eighteen pounds pressure, the communication is opened between this vessel and the smaller cylinder, and the steam in each of these will be brought to nearly twenty pounds pressure, which steam will be used in the great cylinder at the next stroke. But at the end of each stroke of the pistons, before the opening is made between the smaller cylinder and the steam-vessel, the steam in the smaller cylinder will be, as before stated, at about fifty-four pounds; in the steamvessel it will be at about eighteen pounds, and in the larger working cylinder at about eighteen pounds also. Hence the medium pressure on the piston of the smaller cylinder will be about thirty-five pounds on the inch, while the medium pressure of the steam on the piston of the great cylinder will be about nineteen pounds on the inch; for it will be about twenty pounds at the beginning and about eighteen pounds at the end of the stroke. If the steam-vessel be made larger, the difference at each end of the stroke will not be so great. If the steam was let out at fifty-four pounds from the smaller cylinder to the open air, there would be but thirty-nine pounds upon each inch of the piston in consequence of the re-action of the atmosphere, equivalent to about fifteen pounds per inch:

[graphic]

thus, by letting the steam pass from the smaller cylinder to the steam-vessel, instead of letting it out to the open air, it loses about four pounds on the inch of the small piston, but it gains about twelve pounds on the inch of a piston three times as large; and, there being but half the steam required in the common way to condense, there must of necessity be a considerable gain. If the friction and loss of force be equal to nine pounds on the inch, on the piston of the smaller cylinder, there will be but about thirty pounds on the inch neat power, when the larger one will work about twelve pounds on the inch. Here, too, if the large cylinder, or piston, or airpump, or condenser, should be out of order, the small piston may still be worked, by disengaging the large piston from the beam: on the other hand, if the smaller piston be out of order, the large one may still be worked, while the other is disengaged. The steam-vessel is to be made of wood, that it may transmit the heat slowly, and the cylinders may be placed within it if found

convenient.

436. Mr. James has taken out a patent for a boiler, which, with some modifications, promises to be of great importance. It is formed by a number of annular tubes, arranged close together sideways, so as to exhibit a cylindrical shape externally; these tubes have apertures communicating into each other at opposite extremities of their diameters, arranged in two lines, one of which is at the bottom, when the boiler is fixed horizontally in its place, and the other line at its upper part. It is stated, at the end of the specification, that the shape of these rings may be elliptical or circular, and that round or other shaped tubes may be used for them, if preferred to those represented in the drawings, which are square, and such as might be produced by annular partitions soldered in between two hollow concentric cylindrical vessels.

437. The fire-place or furnace for this boiler is placed within it, and consists principally of a grate, arched upwards in the middle, supported by a bearing bar at each side, which passes through the boiler, and is sustained by the iron frames which support the doors of the furnace, and are put in front and the termination of the fire-place.

438. This compound boiler is moreover enclosed by a double cylindrical case, so as to leave some space between it and the case, in which the flame or hot vapors from the fire may circulate; while the internal part of this double case, being filled with charcoal dust, confines the heat more effectually. A flue rises from the top of the farther end of the case to convey away the smoke, which, however, is made to descend near the bottom of the boiler before it enters the case, by a partition at the farther extremity of this latter, whose only aperture is at its bottom.

439. A tube enters into the boiler in front, a little above its horizontal diameter, for the convevance of water, and a pipe passes out from it at top, also in front, through which the steam is to pass to the engine; the water pipe is furnished with a peculiar cock at the level mentioned, which revolves by the motion of the engine, and is intended to prevent the water from rising

any higher in the boiler, when it ascends to that line, though it admits its entrance whenever this is lower; but the mode in which the cock is to produce this effect is not fully explained.

440. The boiler being thus prepared is to be filled with water a little above its horizontal diameter, as above mentioned; and, the fire being then kindled, the patentee states that the flame or hot vapor from it will descend between the case and the boiler, and make the water in the latter boil; the steam from which, in passing through the upper parts of the tubes above the fire, will be farther heated, so as to produce an increased effect.

441. To facilitate the cleansing of this boiler from the sediment of the water, it is to be supported in front by four rollers, placed at equal intervals about it, in the iron frame which sustains the case and furnace, and at the back by a pivot in the centre of the partition at its end, which pivot passes through the case, and rests on the frame just mentioned; a winch is to be fixed on this pivot, and a handle at the same time is to be attached to the boiler in front, at a similar distance from its centre, by which two gripes it can be turned round, or made to vibrate backwards and forwards when required. When this operation is to be performed, the patentee directs that the furnace is to be taken out from the boiler, and all impediments to its circular motion to be removed; it is then to be nearly filled with water, and, shot or marbles' being previously put into each of its annular tubes, the whole is to be turned or made to vibrate as mentioned, which he states will be sufficient to detach the sediment from the parts to which it may adhere, and cause the whole to run off along with the water when this is discharged.

In

442. The gas-fire or water-burner is the name given to a new method of producing light and heat, invented by Mr. Morey, by which he conceives that all carbonaceous fluids may be conveniently burnt, and derive great force from their combination with the oxygen and hydrogen of water or steam at the moment of ignition. the first form of this experiment a tight cylindrical vessel, containing resin, was connected with a small boiler by a pipe, which entered near the bottom and extended nearly its length, having small apertures over which were two inverted gutters, inclining or sloping upwards over each other; the upper one, which was longer than the other, being intended to detain the steam in the resin in its way to the surface. When the resin was heated, carburetted hydrogen gas issued from the outlet or pipe, inserted near the top of the vessel, and, being ignited, afforded a small blaze about as large as that of a candle; but, when the steam was allowed to flow, this blaze instantly shot out many hundred times its former bulk, to the distance of two or three feet. Tar succeeds better than resin, and has therefore been used in the steam-boilers.

443. We have, on several occasions, been obliged to refer to the horse-power' as it is called, of various engines, and it will be necessa ry in a future page to examine this mode of estimating force somewhat more in detail; at present a few facts connected with the single and double acting engine may not be misplaced.

« PreviousContinue »