DESCRIPTION OF THE FRONTISPIECE.

THIS Plate represents a front view of a Steam-Engine connected with a Sugar-Mill, as constructed by Messrs. Taylor and Martineau, who have kindly permitted our draftsman to make a drawing of it.

This Engine, being only twelve times larger than the drawing, is, from its compactness and simplicity of construction, peculiarly applicable to most of the manufactures round the metropolis, where power of a moderate amount is in general required.

It works horizontally, at from 30 to 40lbs. pressure per square inch, without condenser, having metallic pistons and slide-valves, and only requires eight screw-bolts to fasten it to oak sleepers, or frame-work of moderate scantling.

A is a crank connected with the piston-rod, which, as it works in the cylinder horizontally, cannot be seen. B is the cylinder, into which steam is admitted from the boiler, by means of the pipe CCC. The amount of steam flowing into the cylinder is regulated by the throttle valve at D, which is opened and shut at proper intervals by the rod E E E. FF is the governor, or regulator, consisting of two heavy balls, with the sliding collar a, suspended from the top of a vertical spindle b b. at the axis c. This spindle is connected with the main shaft, by a strap passing over the sheeves or pullies, G G G, which cause it to revolve; and as its speed varies with that of the main shaft, the governors F F, according as its speed increases or decreases, have a tendency either to fly from, or approach to, the spindle. This rise or depression of the governor affects the rod E E E, to which it is connected, and regulates the quantity of steam flowing from the boiler into the cylinder.

H is a piece to connect the top part of the piston-rod with the rod I, so that by the motion of the crank the rod I is also moved, which rod moves the slide valves in the cylinder K. By the action of these valves, steam is alternately admitted on the opposite sides of the piston; and as the engine does not condense its steam, there are two pipes, placed one at each end of the cylinder, to carry it off. One of these pipes is seen at N. When the piston has been driven by the force of the steam to the other extremity of the cylinder, the steam, by the action of the slide valves, is shut off from this end, and allowed to flow into the

opposite end of the cylinder; the orifice of the pipe N being at the same time opened, the steam at this end is, by the returning action of the piston, driven through the pipe N, and conveyed away under ground, leaving this end of the cylinder ready for a fresh supply.

The power generated by this simple arrangement is made to effect the required purpose by means of the shafting O O O. On this shafting, at a little distance from the engine, is an eccentric, L, to raise the rod M, to pump water into the boiler when required: and at nearly the further end of the shafting is another eccentric, W, which imparts motion to the rod V, for the purpose which we shall hereafter describe.

The rotatory motion which the crank has received from the engine is imparted to the shafting, to the eccentric L, the coupling-box d, the fly-wheel P, the eccentric W, and the pinion Q, which plays in the large cog-wheel, R, on the shaft S, and thence is imparted to the rollers of a sugar-mill, which rollers are moved at equal speeds by the pinions UU.

In this, and most other Sugar-mills, there are three rollers, two at the bottom, and one lying between the other two at the top. Through these rollers sugar canes are passed, and the compressed juice falls into a receiver, from whence it is pumped, by the movement of the rod V, into a copper, or other receiver. At that part of the shafting marked e e, sufficient space is left to allow of play when the canes are passed through the rollers, otherwise the shafting would be very apt to snap and be destroyed.

THE

OPERATIVE

MECHANIC AND MACHINIST.

OF THE ACTION OF FORCES.

ALL matter is continually under the operation of forces, which, if acting upon it equally, and in opposite directions, maintain it in a state of rest. But if a newly created force act upon a body in such a direction, and to such an extent, as to overcome the forces under whose action that body, in common with all other matter, exists, the result will be motion communicated to that body; and in an exact proportion as that newly created force exceeded the amount of forces that were previously acting upon it in the opposite direction. For example, if a man lift a pound weight three feet from the ground, the amount of motion created by that action is exactly equal to the amount his newly created force exceeded the force of gravity or weight which acted on the matter: for if his force had not exceeded the force of gravity, it is manifest that that motion could not have been created; and if the force of gravity had not existed, it is again manifest that the amount of motion would be exactly in proportion to the amount of the whole of the force he had applied. Again, if his force only exactly equalled, and did not exceed the force of gravitation, motion could not have taken place, and the body would have remained at rest.

This state of rest, maintained by the contrary action of two equal forces upon a body, is called equilibrium. But the term equilibrium is most commonly applied when one or more bodies are, by the mere force of gravitation, maintained in a state of quiescence, or rest: thus, if a bar of iron, A B, fig. 1, is supported at its centre C, it will balance, or remain horizontal, as the quantity of matter in CA is exactly equal to that in C B, and the amount of the gravitating force proportional to the quantity of matter that is in each arm of the bar: likewise, if a ball, A, fig. 2, be acted upon by a force at B, and by another force, exactly equal, at C, the ball A will be maintained in a state of quiescence, termed equilibrious.

B

In the common operations of mechanics, the former state of equilibrium frequently occurs; the latter rarely, and never with any permanent duration; by the term equilibrium, therefore, in general, is understood, the position first cited.

Upon duly considering that matter, when between forces acting in opposite directions, is in a state of equilibrious quiescence, it will be manifest, that motion cannot be obtained without destroying the equilibrium. It must not therefore be supposed, that the forces of gravitation or adhesive attraction can produce motion, as has been erroneously urged by some, but rather that all the motion these powers are capable of producing was primarily exerted to bring matter into that state of equilibrium in which we find it. Wherever that equilibrium is disturbed by extraneous causes, the resultant motion, attainable by such disturbance of the general equilibrium, has long since been known, and applied to useful purposes. We may with propriety, therefore, deduce from these considerations, the perfect fallacy of that most ruinous and speculative notion of a perpetually moving force. Many who have wasted their time in attempts to attain that object, have either supposed that the force of gravitation could obtain motion, or that motion once obtained could of itself increase its force; which was about as rational as to suppose that any substance could of itself increase its own bulk. The powers with which nature has supplied us, have, as far as we are aware of, been already applied; and should there be others existing of which we are ignorant, or which we have not reduced to our command, the search for, and developement of such objects, are praiseworthy and valuable: but let us with confidence hope, that the labours of ingenuity will no longer be drawn aside from the paths of prolific study, by this destructive phantasy.

Returning from this digression, when a body is operated upon by a force, and acquires motion, that motion, taking into account the amount of space through which the body passes in a given time, is called the velocity of the body; and according as the extent of distance increases or decreases in a greater or less period of time, the velocity is said to increase or decrease.

If a force acting upon any body, and causing motion, shall continue to act upon it in the same direction, so as to continue to increase that motion, the body, under such circumstances, is said to attain accelerated velocity. And