In the two cheeks of the frame A B, are cast or bored two round holes for receiving the gudgeons of the swivel E, one of which gudgeons is also seen at E, in [fig. 2]. This swivel turns in these holes; and it is itself perforated with a round hole just large enough to receive freely the body of the mandrel F G. This mandrel has now on it the cylinder, which is to be taken off. I K are, moreover, two ears or studs cast or welded on to the top and bottom of the said frame A B, and at exactly the same distance from the centres of the swivel E before-mentioned. These ears receive the ring-formed ends of the bars L M; see also the bar L, in [fig. 2]. To these bars is firmly fixed the cross-bar N O, which forms the nut of the screw P, by means of which the operation of the machine is duly prepared; for, now the cup Q (in the centre of which the screw P revolves against a proper shoulder) receives the end G of the mandrel, which it presses forcibly, while the whole is in the position E L, of [fig. 2]; that is, when the two centres E and R form one right line with the bar L, [figs. 1 and 2]. To complete, then, the process of driving out the mandrel, the bars, mandrel and cylinder are, at once, strongly made to describe the arcs a M b, a c; the mandrel revolving round the centre E, which is that of the swivel and the bars round the stud R. But, in thus revolving, a given point of the mandrel describes the quadrant a M B, and a contiguous point of the bars L M describes the quadrant a c; insomuch, that the mandrel must have been forced out of the cylinder in direction G F by the distance c b; where we observe that, at the beginning of this motion, the two curves a b and a c coincide in their movements, and only begin greatly to diverge from each other in the latter parts of these motions (see M b c.) The power, then, of this machine, when the cylinder sticks fastest to the mandrel, is infinite: and this power becomes weaker, and the velocity greater toward the end of the operation; that is, when the cylinder has slackened on the mandrel, and no longer requires to be driven with the same force as at the beginning. It may finally be observed, that the bars L M are suspended by an oblique bar or chain S N to the ceiling of the room just over the stud R or I, which is their real centre of motion, in the above-described process.
OF
A SYSTEM OF MACHINERY,
For cutting and trying Tallow by Power.
The wheel A B, [Plate 30], [fig. 3], was a horse-wheel, but may be a first motion of any given kind. It is placed on the ground-floor; and over it’s centre is another shaft, having on it’s upper end a chopping block C, which revolves with the wheel A B, as turned from below. In this wheel, A B geers a pinion D, driving the lateral shaft D E, which has two functions: the first to work the lying shaft F, and by means of the cams G H, to lift the contiguous stampers; and, by means of the knives I K, to cut the tallow on the revolving block before-mentioned. Over this block is fixed an oblique scraper, which takes the tallow as soon as it is cut, and pushes it down an inclined channel, placed at C x, into the boiler. The second use of the shaft E is to turn the mill M, (better shewn at [fig. 4]), which is let down into the boiler, in one stage of the process, and drawn out by the tackle N, when not wanted. The use of this mill is to tear the fleshy parts of the substance, while in the act of boiling, and thus to disengage the tallow with so much the less heat, in order that it may be so much the less coloured. Besides this machine, there is a grapple L to be first used, which stirs the tallow in the boiler by the rotatory motion of the arm x. This position of the grapple would alone indicate what I have yet to observe—namely, that the boiler is a kind of ring, the section of which is the line 1, 2, 3, 4, and it’s depth 1, 2, or 3, 4. To prevent, still further, the fat from being burnt or coloured, the flue for the fire is conducted solely under the bottom of the boiler, as shewn by the dotted lines in [fig. 5]: the smoke or heated air being forced to make two revolutions under it, as indicated by the arrows in this figure, where we see more particularly the fire-place F in close connection with the rising shaft of the chimney at G; and this is so, because, with so great a length of horizontal flue, the fire would not enter the chimney till it had been heated to a first degree. There is, therefore, an opening into the chimney at a, and the fire, in lighting, is suffered to escape directly from the fire-place into the chimney; by which means, continued a few minutes, there is draught enough created to make the fire take its useful course through the flue afore-mentioned. I may just observe, reverting to [fig. 3], that O shews the fire-place in elevation, and p the entrance into the flue, which last is double under the boiler, as shewn in [fig. 5]. Finally, the [4th fig.] shews an end view of the tearing-mill, before-mentioned; but here on a larger scale, A B being a part of the side of the boiler.