almost infinite variety of different powers, and this variation is obtained without the least alteration of any part of the machine. If, in unloading a vessel, there should be found goods of every weight, from a few hundreds to a ton and upwards, the man that does the work will be able so to adapt his strength to each as to raise it in a space of time proportionate to its weight; he walking always with the same velocity as nature and his greatest ease may teach him. It is a great disadvantage in some cranes, that they take as long time to raise the smallest as the largest weight, unless the man who works them turn or walk with such velocity as must soon tire him. In other cranes, perhaps, two or three different powers may be procured; to obtain which, some pinion must be shifted, or fresh handle applied or resorted to. In this crane, on the contrary, if the labourer find his load so heavy as to permit him to ascend the wheel without its turning, let him only move a step or two toward the circumference, and he will be fully equal to the task. Again, if the load be so light as scarcely to resist the action of his feet, and thus to oblige him to run through so much space as to tire him beyond necessity, let him move laterally towards the centre, and he will soon feel the place where his strength will suffer the least fatigue by raising the load in question. One man's weight applied to the extremity of the wheel would raise upwards of a ton; and it need not be added, that a single-sheaved block would double that power. Suffice it to say, that the size may be varied in any required ratio; and that this wheel will give as great advantage at any point of its plane as a common walking-wheel of equal diameter, as the inclination can be varied at pleasure, as far as expediency may require. It may be necessary to observe, that what in the figure is the frame, and seems to form a part of the crane, must be considered as a part of the house in which it is placed; since it would be mostly unnecessary should such cranes be erected in houses already built. With respect to the horizontal part, by walking on which the man who attends the jib occasionally assists in raising the load, it is not an essential part of this invention, where the crane is not immediately contiguous to the jib, although, where it is, it would be certainly very convenient and economical. Notwithstanding, however, the advantages which have been here enumerated, Mr. Whyte's crane is subject to this theoretical objection, that it derives less use than might be wished from the weight of the man or men: for a great part of that weight (half of it, if the inclination be 30 degrees) lies directly upon the plane, and has no tendency to produce motion. Besides, when this crane is of small dimensions, the effective power of the men is very unequal, and the barrel too small for winding a thick rope: when large, the weight of the materials added to that of the men put it out of shape, and give it the appearance of a large, unwieldy, moving floor. We know one large crane of this construction, which has an upright post near the rim on each side, to support it and keep it in shape; and, as much as possible to prevent friction, each post had a vertical wheel at its top. We were informed this crane was seldom used, and that it was soon put out of order. Nor, moreover, is it every situation that will allow the crane-rope to form a right angle with the barrel on which it winds, and when this angle is oblique the friction must be much increased. The friction arising from the wheels at top of the vertical crutches might, indeed, be got shut of, by making the inclined wheel very strong; but this would add greatly to the friction of the lower gudgeon of the oblique shaft, and considerably enhance the expence of the machine. 8. There remains, then, another stage of improvement with regard to the structure of cranes, in which the weight of the labourers shall operate, without diminution, at the end of a horizontal lever; and in which the impulsive force thus arising may be occasionally augmented by the action of the bands either in pushing or lifting. This step in the progress has been lately effected by Mr. David Hardie, of the East-India Company's Bengal warehouse. After a few preliminary observations, we shall point out the distinguishing particulars of this gentleman's invention. The capstan, the wheel and pinion, with a winch, and the walking-wheel, are the cranes in common use at the present time; though a slight view of the method of working these machines might be sufficient to shew that they are essentially defective in regard to the grand object in procuring the force of men, on which the quantity of work performed necessarily depends. The capstan and walking-wheel call for little or no use of the arms; and the crane of the wheel and pinion derives very little advantage from the legs, while the force of the men acting upon the winch must of necessity be very fluctuating. At the capstan, and wheel, and pinion, a considerable force is expended unproductively in giving action to the greater part of the men's weight, which does not contribute to the moving power of the machines; the power actually exerted seldom exceeding 20 lbs. at a moderate velocity. The merchants and wharfingers would instantly discharge from their service any porter who would refuse to carry a load of more than 20 lbs., yet these very merchants and wharfingers are daily paying full wages to cranemen for exerting a force which, when duly ap plied, is greatly within the power of a boy of ten or twelve years of age. And as to the common walking-wheel, the men who are stationed within it expend a great portion of their strength in moving themselves forward; which proves unproductive, because the effective velocity is only according to the sum of the heights attained, and the waste of force through such unprofitable deviation from the vertical direction renders the men incapable of the due velocity of ascent: besides, the velocity of descent, which ought to be proportional to a due velocity of ascent, is materially impaired by the shortening of the effective lever in the course of its depression, and a consequent diminution of mechanical power; and these obstructions are frequently aggravated, by placing men in the wheel to walk behind the others. And when this loss of labour by the often counteroperation of a rear rank is avoided by applying an additional wheel, the machine occupies much space, becomes extremely expensive, and is attended with extraordinary friction. Although nothing but necessity can justify the hazarding of the lives of men, yet the walking-wheel is attended with imminent danger; and being a very defective engine, employed without either necessity or expediency, those persons who use them are responsible to humanity for the shocking disasters they frequently occasion. But the various evils just enumerated, as well as many others which attend the cranes now adverted to, have been obviated in a very effectual manner by Mr. Hardie; whose crane is at once so simple and efficient, as to render it no easy task to point out any faults which it has not avoided, or any defects which it has not supplied. It is a walking-crane; but the men walk on the outside of the wheel, instead of inside of the rim; and during the whole of their labour they are exposed to no kind of danger, and they can walk in an upright posture, well suited to free respiration. Five cranes of the kind are at work at the East-India warehouses: and as the contrivance (for which Mr. Hardie obtained a patent about 1803,) must ultimately prove a considerable acquisition, we have examined the construction and mode of operation of two of these machines with particular attention, that we might be enabled to furnish the public with the following description. The reader may turn to plate XI. where fig. 1. is an elevation of the side of the crane on which the men operate. Fig. 2. An elevation of the end of the stage to assist the men in stepping on and off the wheel, as well as to support a seat for them to rest upon, in the intervals between the operations. The edge f of this stage does not stand more than 4 inches from the point s by which the edge of each step passes. Fig. 3. An elevation of the end of the wheel. Fig. 4. An elevation of the side of the crane, opposite to that given in fig. 1. The same letters of reference being put to the corresponding parts in these figures. AA is a wheel (on the principle of the wheel used in China for men working at the chain-pump, for raising water to the higher grounds, employed in the culture of rice), on the outside of which are placed 24 steps for the men to tread upon, at a situation where the steps are found at a height equal to that of the axis, or where the plane of the steps becomes horizontal; the diameter of the wheel being 6 feet, steps included. The crane represented in the figure is adapted for 4 men; though they may easily be contrived for 5, 6, or 8. At one end is B, the crane rope barrel, of a diameter suited to the drafts of goods commonly raised, and the number of men generally allowed, with ca brake-wheel, all fixed on the same axis, and D a brake attached to the framing of the crane, to press on the brake-wheel, occasionally to stop or retard the motion; being conducted by a man at the loop-hole by means of, a lever of wood, loaded with a piece of lead or cast-iron at the extremity, to give it sufficient weight to stop the motion of the wheel; a rope fastened to the end of this lever, and conveyed over two pulleys, terminates in a handle for the loop-hole man, with an iron ring at the lower part thereof to receive a pig, fixed at the side of the loop-hole for the purpose of keeping it down, that the lever might disengage the brake from the brakewheel during the operation of raising the goods. G, G, G, G,G, are vertical handles, and H, H, H, H, H, horizontal handles for the men to take hold of with both hands, when treading on the steps: sometimes both hands are applied to the vertical handles; at others, one hand to a vertical, and the other to a horizontal handle; and at others, both hands to the horizontal handles; thus producing a variety in the action, and, when necessary, a considerable augmentation to the force. 1 (fig. 1. and 3.) is a pawl which drops in at every step, to prevent the wheel and its incumbent weight from overpowering the men at any time: it has at its lower part a cord with a loop to pass over one of the horizontal handles, near the extremity of which there is a notch sufficiently deep to retain the loop when drawn into it, for the purpose of raising the pawl, to disengage it from the wheel preparatory to the operation of lowering the goods or crane rope. Now it is obvious, that by treading on the steps as they arrive at the position t, t (figs. 1. 3.), just above the horizontal plane, passing through the axis, the men both ascend and descend nearly in the vertical direction: of consequence, the greatest possible velocity is produced without any unproductive labour; and the men are enabled to maintain the action by means of a hold of an upright handle on each hand; or occasionally to augment the action, by pushing at these handles. Further, by taking hold of the horizontal handles, each man can, by an act similar to that of lifting, augment the force arising from his weight through all the degrees, from about 150 to 300 lbs. So that the same number of men can perform many operations of raising greater drafts than usual; such as with the common walking-wheel or most other cranes could not be accomplished without additional men and the pawl which drops in each stop provides in the most effectual manner for the safety of the men, even if the crane had not been so constructed that their feet need never be more than 12 inches distant from the stage sf, and the distance fs far too small to admit of falling, through. Thus the very judiciously chosen dimension of a 6-feet diameter unites the advantages of a weight acting on a horizontal instead of inclined lever with those accruing from the vertical and horizontal handles; while it completely precludes the danger which attends the common walking-wheel, and has by no means so much friction as necessarily attends Mr. Whyte's crane. Mr. Hardie has likewise contrived a truly advantageous mode of operating without a gibbet, which he has carried into effect. with four of his cranes. He has placed the crane at the top of the warehouse, so as to allow the crane-rope to drop directly down from the barrel of the crane in front of the loop-holes; and at the upper floors, where the shortness of the rope dimi-. nishes the swing of the goods in or out of the loop-holes, he has provided a sliding floor immediately under the floor of the warehouse, which one man draws out or in, by pulling a cord, with the greatest ease, to receive or deliver the goods by a truck at the loop-hole. The part of the warehouse floor which is immediately above the sliding floor consists of a thin plate of cast iron, which allows the truck to run off the one on the other without any obstruction. Thus more than one man's labour in five or six is saved, by getting rid of the friction of the pulley of a gibbet; and a still greater saving of labour is effected by accelerating all the movements at the loop-holes. 9. The common method of lowering goods by the brake and brake-wheel, even with the assistance of a counter-weight, is liable to injurious accidents to the men, as well as to the goods, when they consist of perishable articles, such as wine, spirits, glass, &c. Sometimes, from the rapid motion of the crane, parts of it fly off with violence, and kill or wound the persons near it at other times the brake-rope becomes entangled by turning off the pulleys or otherwise, or the rope slips out of the hand of the man who conducts it: in either of which cases the |