22 196 98 22 198 99 22 198 99

7,392

462,000 9.0 126 63

8,448

528,000 8.7 140 70

9,504

594,000 85

153 761

3,300 3,630

660,000 8-3 166, 83

726,000 8.0

176 88

3,960 51

792,000 7.8

187 931

4,290 5

858,000 7.6

197 98

56 28 38. 58 29 38.8 60 30 39-2 62 31 39.8 64 32 40-4 66 33 41. 68 34 41-6 70 35 42. 72 36 427 74 37 433 76 38 43 7 78 39 44-4 80 40 45 85 42 46-2 90 45 47.5 95 47 48 7 100 50 50. 105 52 51 110 55 52-2 115 57 53-4 120 60 547 126 63 56' 132 66 57 136 68 58 140 70 59 145 72160151 7561

1172 20-2 1206 20-1 7.8 9,428 71 124620.1 7.8 9,742 7 1280 20.0 7.85 10,057 7 1320 20.0 7.9 10,371 7 1360 20.0 7.9 10,686 7 1386 19-9 80 11,106 8 1433 19-9 1472 19-9 1505 19.8 1544 19-8 8-0 1590 19-8 8-0 1674 19-7 8-2 1773 19-7 8-2 1862 19-6 8-2 1963 19-6 8-2 16,176 2043 19-5 8-2 16,995 2145 19-5 8.5 18,333 2242 19-5 85 19,166 9 2340 19-5 8.5 20,000 9 246319-5 8.5 21,000 2552 19-4 8-5 22,000 9 264219-4 8-6 22,666 9 273419-48-6 23,503 9 2827 19-48-6 24,413 9

7-79

9,114 7

11,423 8

11,740 8 12,058 8 12,375 8 12,692 8 13,750 8 14,558 81

12

15 210 105 15 210 105 15 210 105 15210105 14 210105 14 210 105 14 210 105 14 210 105 14 210 105 14 210 105 13 208 104 13 208 104 13 208 104 13 208 104 13 208 104 13 208 104 12 204 102 204 102 204 102

227 113

238 119

268 134 279 1394 286 143 294 147

302 151 310 155 317 158 329 1644 336 168

366 183

15,840 16,896 1,056,000 7.1 17,952 1,122,000 7.0 19,008 1,188,000 6.9 20,064 1,254,000 6-8 21,120 1,320,000 6.7 22,176 1,386,000 6.6 23,232 1,452,000 6:5 24,288 1,518,000 64 25,344 1,584,000 6.3 26,400 1,650,000 6-2 27,456 1,716,000 6.1 28,512 1,782,000 6.1 29,568 1,848,000 6.0 30,624 1,914,000 6.0 31,680 1,980,000 5.9 32,736 2,046,000 5.9 33,792 2,112,000 5.9 378,189 34,848 2,178,000 5-8 382191 35,904 2,244,000 5.8 394 197 36,960 2,310,000 5.8 406/203 38,016 2,376,000 5-7 410 205 39,072 2,442,000 5-7 422 211 40,128 2,508,000 5.7 41,184 2,574,000 5.6 42,240 2,604,000 5.6 44,880 2,805,000 5.6 47,520 2,970,000 5.6 50,160 3,135,000 5:5 52,800 3,300,000 5.5 55,440 3,365,000 5.5 58,080 3,630,000 5-5 60,720 3,795,000 5.5 63,360 3,960,000 5.5 66,528 4,158,000 5-5

433 2164 437 218

448 224

476 238 504/252 522 261 555 2771 577.2884

632 316

216 108

249 1241 258 129

348 174 354 177

605 3021

99

103197

99

The third column of this table also shows the force which is communicated to the fly-wheel, expressed in decimals, the force of the piston being 1.

445. The above table explains itself by the titles of its different columns; and it is only necessary to remark that the variations of force are not to be considered as an absolute less of power, because, when the crank has but slight power, or arriving towards the top or bottom of the stroke, the piston descends proportionally slow; and in consequence the steam has more time to flow into the cylinder, and press upon the piston with a greater power; therefore, what the piston loses in force upon the crank, it makes up in some degree by an increase of its force; and, from moving slower, it consumes less steam than when moving with its whole velocity, and acting with full force upon the crank. Hence both the power and the velocity of the piston in the cylinder are to be considered as varying continually; and, if the fly is sufficiently heavy, it will be found that the rotative motion is very nearly regular, while the ascent and descent of the piston are accelerated from nothing at the top of the cylinder, to its greatest velocity at the middle, or near the middle, and from that point it is retarded, till it comes to nothing at the bottom

of the motion. The table shows the exact incre 'ments and decrements.

446. Mr. Taylor has made considerable improvements in the steam engine. His last patent consists of an arrangement of the piston rods of cylinders of steam engines, when in an horizontal or inclined position, to prevent the pistons from pressing unequally on the cylinders, and a method of combining two or more cylinders so as to direct their joint powers to one operation.

447. The patentee directs, for attaining the first object, that the piston rod shall pass through the piston, and out through the opposite end of the horizontal or inclined cylinder, being provided with fit stuffing boxes at both of its extremities, and that each end of this long piston rod shall be furnished with a vertical wheel, grooved at its rim, and moving between two metal guides, parallel to each other, and to the sides of the cylinder. These guides, being of course one above and the other below the wheels, would prevent the weight of the piston from making it press too much at the lower side of the cylinder, if the rod were perfectly inflexible; but, as this cannot be, the patentee supposes that he will effect his purpose by causing considerable weights to act on each end of the rod in opposite directions, by appending them to the horizontal arms of bell cranks,' or bent levers, so as to tend to keep the rods straight by their being in a state of tension. These weights may either consist of pump rods at each extremity when the engine is employed in pumping the water from deep mines, or a pump rod may be at one extremity and the weight at the other, in which latter case the power of the engine exerted in lifting the weight would not be lost, as the weight would react on the piston rod in its descent, and assist the engine in lifting the pump rod and water at its opposite extremity.

448. It is obvious that these engines may be employed in producing rotary movements for mill work, as well as those of a reciprocating nature mentioned; but with the rotary movement the tension of the piston rod would not be effected, without weights being appended for this purpose to the bent levers at each of its extremities.

449. The action of two cylinders managed in this manner may be combined by placing them parallel to each other, and uniting their piston rods at each end to strong cross pieces, from the middle of which rods are to proceed to the bent levers, weighted as before. In the specification two cylinders are represented, lying on the same horizontal plane, and having the wheels and guides at each end of the cross pieces, instead of being in the same line with the piston rod; but it is evident they may be placed one over the other also on the same principle, and that any number of them may be combined in this manner by properly disposing the cross pieces and wheels, which latter, however, need not be multiplied as the number of cylinders are increased, as the same number of wheels that will serve for the piston rods of two cylinders may also be made to support those of several more.

450. A method of binding these cylinders down firmly to their supports, whether the latter

are constructed of stone or of cast-iron, is described by the patentee; as is also the mode of disposing the tubes that convey the steam to the several cylinders, and from them to the condenser, or to the open air (according to the nature of the engines), so as to make one set of valves or slides serve for them all. But as there is nothing particular in the arrangement of these tubes, or in the method of fastening down the cylinders, being such as may be easily conceived, they do not require further explanation.

451. The steam carriages described in Mr. James's specification are intended solely for common roads. Instead of the former method, of using one steam cylinder, or at most two, for each steam-carriage, the patentee directs that a steam cylinder shall be used for each wheel, and in his draft, in fact, two cylinders are represented at each extremity of the two axles, so that eight steam cylinders will be required altogether for this plan.

452. These cylinders the patentee states are to be very small, but does not mention their precise dimensions; and, as the pistons of each pair of them are arranged to operate so on the cranks with which they are connected, that when one is vertical the other will be at right angles to it, to save the use of fly wheels, every pair may be considered as one engine acting on the wheel which it is intended to move. These cylinders are placed beneath the axles of the carriage, and the cranks are fixed above them, and each of these cranks is furnished with a spur wheel, which, by another wheel of the same sort, acts on a toothed ring, attached to the nave of the carriage wheel, which nave turns freely on its axle. From these cylinders, pipes run to the steam boiler, on which cocks are so placed that, by turning them in certain directions, the steam may be let on or shut off from each pair of cylinders as required, and also may be admitted partially sometimes; by which means each wheel can have its degree of velocity regulated in respect to that of the others, as may be best suited for making the carriage turn round a corner, or move in any curve de

sired.

453. The steam boiler is placed beneath the perch, near the hind wheels, and the chimney still further back, together with the seat of the engine-man, who not only keeps up the fire, but, by handles placed near him, which communicate with the cocks before mentioned, can stop either of the hind wheels or diminish their motion, as may be most suitable to the slope of the hills, in descending which locking of the wheels might be necessary. The engines used with these carriages are to be of the high pressure species, so that the steam might be discharged from the cylinders at once after being used; but to obviate the inconveniences which this would cause, pipes pass from them to the chimney, to carry off the waste steam along with the smoke.

454. The front axletree is made to turn on its centre as usual, and the steam pipes on it have joints at the centre of motion, similar to those of cocks, to admit of their being turned along with it; a segment of a horizontal toothed wheel

is attached to this axle, in which a pinion works, from which a vertical shaft ascends to the scat of the director, which is placed directly above it, and is constructed like a coach-box. On the top of this shaft a horizontal wheel, furnished with handles like the steering wheel of a ship, is fixed, by which the director can turn the front axletree as the curvature of the road may require. Horizontal rods are also so arranged, between this axle and the cocks, that in proportion as it is turned the steam may be shut off from the cylinders at the side next the centre or centres of the curvature of the road, by which means the wheels at that side move more slowly than the others. Besides the steering wheel, there are two levers with handles, placed near the seat of the conductor, which communicate by cranks with the rods just mentioned, by which the cocks are turned, and by moving which he can either diminish the motion of the wheels at one side, as he pleases, or stop off the steam from all the cylinders at once, when it is required to stop the progress of the carriage.

455. Mr. Vaughan's steam engine is of a very peculiar kind. An idea of its arrangement may be formed by supposing the cylinder of a single steam engine to be placed with its bottom upwards, and another similar cylinder to be fixed in the usual position directly upon it, so that the piston rods of both may be in the same vertical line. Each of these cylinders has its separate piston, and the two piston rods are connected together by two bars, which pass outside the cylinders, from the ends of a cross-piece on the extremity of one of the piston rods, to the ends of a similar cross-piece on the extremity of the other piston rod; the two pistons being previously so placed that one of them shall be near the open end of its cylinder, when the other is near the closed end of that in which it moves. A case is directed to be put over the two cylinders, to confine the heat, and the openings between this case and them at each end are to be closed, so as to exclude the air. A pipe, furnished with a cock, is to pass from the steampipe, near where it enters the valve box, to the inside of this case, to convey steam into the space between it and the cylinders when the cock is opened, to keep the cylinders hot; and from the lowest part of the case another pipe passes out, furnished also with a cock, to let off the water formed within the case by the condensation of the steam. The bars which connect the two piston rods pass through tubes of copper or other metal, placed vertically between the case and the cylinders, and fastened at each extremity to the ends of the case so as to be airtight.

456. The valve box is fixed at the junction of the two cylinders, and in it a sliding valve is used, having a cavity within it, which, as it is moved up and down, alternately forms a communication between the passages that lead to the two cylinders and those which go to the steam-pipe and to the condenser, the rod which works this valve passing through a stuffing box at the top of the valve box. The beam of the engine is to be connected with the piston rods by the links of the parallel gear being joined to

the upper cross-piece, that unites the piston rod to the vertical bars. The valve rod is to receive its motion from some of the working parts of the engine in the usual manner, and the boiler, and all other parts not particularly described, are also to be constructed as shall seem best to the engine maker. Nothing more being peculiar to this engine, except a pipe for conveying oil above the lower piston, which passes through the case and the lower cylinder near where it joins the upper one, and which is furnished with a cock, and a small upright tunnel at its outer end, to receive the oil.

457. The patentee mentions that the cylinders of this engine and the case may either be all cast together, or in separate pieces, to be afterwards united; and that the partition between the two cylinders, where they meet, may be cast with them, or be made separate and bolted in afterwards.

458. A correspondent in Brande's Journal describes a steam engine indicator' which is really a valuable invention. He says this instrument which has been long known to engineers, though I believe never publicly described, originated with our illustrious countryman, the late Mr. Watt. That which was employed in our works was made from a description of the instrument given to us by Mr. Field, of London, and was applied with the view of ascertaining in what part the extraordinary friction existed, which had for many months previous prevented the engine from attaining its proper speed.

459. In the first experiments we found, when the whole work was in motion at the usual velocity, that the average pressure upon each square inch of the piston amounted to 11.7 lbs., or about one-third more than it ought to have been; and that at this time the engine, which is of fortyfive horse power, made at Soho, exerted a power, including its own friction, of more than seventy horses. Finding, in repeated trials with detached parts of the work, that the same extraordinary absorption pervaded every department, we became convinced that the effect was produced by some generally existing cause, and naturally directed our attention to the quality of the oil which was in use throughout the work. At one time we were in the habit of using that which is known under the name of neat-foot, but owing to its scarcity, and the extreme cheapness of rape oil, we began, about two years ago, to mix with the former a small portion of the latter. No apparent difference being discovered by the workmen, this proportion was gradually increased, until the stock of neat-foot oil being at last consumed, the rape oil became the sole anti-attrition. And so gradually had the change been effected, that the workmen even to the last denied the existence of any unusual friction, and attributed the want of speed solely to some defect in the engine, which daily exhibited stronger symptoms of being overloaded. At length the use of the rape oil was suspended, and spermaceti substituted; and in twenty-four hours the average pressure was reduced to 9-5 lbs. ; in a week after it had fallen to 91. At this time a mixture of one-third sperm, and two-thirds rape oil was given out to the workmen, and the friction, after

the first day, gradually increased, until at the end of a fortnight the average pressure became 111 lbs. A return to the pure sperm oil again reduced the pressure to 9.5. Subsequent observations have given from 87 to 9-6, but the inconstant motion of the machinery in a cotton mill must at all times produce such a difference.

460. It has long been a maxim with us, and we believe is pretty generally acted upon by those at the head of manufacturing establishments, to receive and adopt the reports of our workmen upon things of which we think they have, from their different occupations, an opportunity of forming a just opinion: the present instance shows, however, that even in a situation where their daily expenditure of exertion was increased at least fifteen or twenty per cent., they were unconscious of the change, and would only be convinced of its existence by a rapid transition from one extreme to the other. The results therefore of experience, or rather the opinions which men form when, from the nature of the subject, their observations are confined to effects alone, ought to be received with care, and acted upon with caution; and it is only upon the unbiassed results exhibited to our actual observation, through the medium of inanimate matter, acting on known principles, that implicit confidence ought to be placed. The indicator is an instrument of this kind; it exhibits to our view the successive changes of pressure which take place in a steam engine cylinder during each stroke; and, by also marking the duration of each particular pressure, it affords, with an elegant simplicity, a very near and correct approximation to the power exerted. The results which it yields are so tangible, and in many situations so important and instructive to those who have the distribution and application of the power derived from steam engines, that we think it only requires to be more generally known and understood, to be oftener applied.'

461. We may now describe the indicator, plate XI.STEAM ENGINE:-A steam engine cylinder cover. B stop-cock, usually made to answer the seat of the grease-cock. C indicator cylinder, about one inch and three-quarters diameter, and eight inches long, open at top, and screwed at bottom upon the stop-cock B. Da flat pillar, screwed to the side of the cylinder C, and supporting the frame EE. F the piston, fitted so as to work easily up and down, and to be, at the same time, air-tight. EE a frame, twelve inches, by seven inside, the under and upper rail grooved to retain the slidingboard K. G the piston rod, about five-eighths diameter, and sixteen inches long. Il a guide screwed to the pillar D, at six inches above the top of the small cylinder, and through which the piston-rod passes. I a spiral spring attached to the piston at F, and the guide at H. It should be about seven inches long when at rest, and of such a strength as to allow the piston to descend nearly to the oottom of the cylinder, when it is loaded with a weight equal to fourteen pounds upon every square inch of its area. It should also admit of being compressed about one inch and a half. K a small board about seven inches square, sliding in grooves in the upper and un

aer rails of the frame EE. La smal brass socket, which may be fixed at any height upon the piston-rod, by the tightening screw M. It carries in the other end a short pencil, with a weak spring to push it forward against the surface of the sliding-board. Na weight attached by a cord to the sliding-board K. O any convenient part of the parallel motion, traversing a space of about four inches and a half during each half stroke of the engine.

462. From this description the principle on which the instrument acts will be evident. By opening the stop-cock B a direct communication is made between the interior of the large and small cylinders, and the density of the steam in the indicator becomes the same as in the steam engine cylinder above the piston. When this density

is less than that under the atmospheric pressure, the indicator piston will sink, when it is greater the piston will rise; but the spiral spring, which, if carefully made, stretches through equal distances with equal weights, restrains the motion of the piston; and, by the distance to which it allows it to move from its state of rest, indicates the pressure it is undergoing. During each stroke of the engine, therefore, the indicator piston will rise at the instant the upper steam valve opens, and during the descent of the large piston will maintain a height proportioned to the density of the steam in the cylinder. When the eduction valve opens it will sink, and by the rapidity of its descent, and the distance to which it falls, denote the quality of the vacuum. If, during this perpendicularly alternating motion of the small piston, the sliding-board be made to perform its reciprocating and horizontal course, the pencil, in the socket L, will trace upon the board, or upon a piece of paper applied to its surface, a figure, something like PQRS; of which figure, the part PQ is drawn during the descent of the large piston. At Q, the condensation taking place, the atmospheric pressure acts upon the piston indicator, and makes it descend until the tension of the spring counteracts the force of the pressure. Meanwhile the engine begins to perform the up-stroke, and, as the board traverses, produces the line RS. When the engine piston arrives at the top, the admission of the steam destroys the vacuum that existed below the indicator piston, and allows the spring to raise the latter until the equilibrium is restored. It consequently follows that the distance between the line PQ, and the line R S, will be greater in proportion to the difference between the pressure in the cylinder during the existence of the va

cuum and the pressure of the steam, and the curve QR be more acute in proportion to the rapidity with which the vacuum is formed. If this distance be measured in eight or ten places, and an average taken, then a simple proportion gives the pressure upon each square inch of the piston. Let a = area of indicator piston,-b, any weight applied experimentally to that piston, -d, the distance to which it falls with that weight, and let e be the average distance taken from a diagram, and f the average pressure in pounds upon the steam engine piston during the b formation of that diagram. Then, as d to

b

b.e

da

- SO a

is e to f, or =f. And as, for every individual instrument, abd are constant quantities, then a, a constant number by which to multiply the average distance obtained from a diagram, for the average pressure in pounds upon each square inch of the steam piston.

a a

463. A table of the amount of work really effected by the principal engines in Cornwall in one month may here be furnished. The whole number of engines reported in the month was, fifty-three pumping engines, fourteen whim engines, three stamping engines. Of the pumping engines fifty are single and three double power, and three of the single power engines have combined cylinders; the diameters of the cylinders as under :

41

do.

do. 80

do.

do.

do.