and is almost unnecessary where such a crane is to be erected in a house already built. In warehouses this crane would be extremely simple and cheap; as the wheel, though of considerable diameter, occupies but little room, from its thinness and inclination. A slit in a floor about two feet wide, with a support above and below for the axis, is all that is necessary to constitute and contain the crane: for goods may be stowed both under the whole wheel, and above nearly half of it; and there would be ample room to stow a large quantity of goods properly sheltered from the weather. Hence, the house would diminish the wharf room much less than many others. One man's weight alone, applied at the extremity of the wheel, would raise upwards of a ton; and a single-sheaved block would double that power: and 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. A represents a circular inclined plane, moving on a pivot underneath it, and carrying round with it the axis E. A person walking on this plane, and pressing against the lever B, throws off the gripe D, by means of an iron rod C, and thus admits the plane and its axis to move freely, and raise the weight G, by the coiling of the rope F round the axis E. To show more clearly the construction and action of the lever and gripe, a plan of the circular inclined plane is added, fig. 2; where B represents the lever, D the spring or gripe. In this plan, when the lever B is in the situation it now appears in, the spring or gripe D presses against the periphery of the plane, as shown by the double line; and the machine cannot move but when the lever B is pressed out to the dotted line H. The gripe is also thrown off to the dotted line I, and the whole machine left at liberty to move. One end of a rope of a proper length is fixed near the end of the lever B, and the other end made fast to one of the uprights, serving to prevent the lever from moving too far, when pressed by the man.

In 1805 Mr. Gilbert Gilpin received the silver medal of the Society of Arts for the invention, in fact, of Mr. Smeaton, above alluded to; the society appearing ignorant that it had been used before. The pulleys were in this machine grooved to receive the lower half of the alternate links of the chain in the same manner as in Mr. Smeaton's. But Mr. Gilpin farther proposes, that the lower pivot on which the vertical arbor of the crane turns, instead of being fixed to that shaft, and turning in a bush or socket fastened in the nether block, shall be fixed in that block, while a socket in the lower part of the shaft shall be made to fit it, and turn about it.

Many practical and scientific men have thought highly of Mr. D. Hardie's crane, of St. James's Street. It will be seen to be on the very principle of the modern tread-mill.

This crane is in fact the same kind of walkingwheel as is used in China for working at the chain-pump, in raising water to the higher grounds employed in the culture of rice. The wheel is six feet in diameter, and may vary in length from six to twelve or more feet, according to the number of men intended to be employed

in working it; on the outside of the whees are placed twenty-four equidistant steps, after the manner of float-boards in a mill water-wheel; these are for the men to tread upon, where the steps are found at a height rather exceeding that of the axis, or just above the position where the plane of the steps becomes horizontal. At one end of the wheel, and upon its axle, is the cranerope barrel, of a diameter suited to the draft of goods, and the number of men generally allowed. The men ascend by a flight of steps to a platform on the same horizontal plane as the axle of the wheel, and which reaches to within a few inches of its rim; on this platform is a seat, on which the men may rest themselves at the intervals between the operations. On the general framework which supports the wheel, there are placed above it, at suitable distances and convenient heights, both vertical and 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; at others, both hands to the horizontal handles; thus producing by either pushing or lifting, or both, a variety in the action, and, when necessary, a considerable augmentation to the force. There 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 any operation of lowering. It is obvious, that by treading on the steps as they arrive at the position just above the horizontal plane passing through the axis, the men both ascend and descend nearly in the same vertical direction, of consequence the greatest possible velocity is produced without any unproductive labor; and the men are enabled to maintain the action by means of a hold of an upright handle in 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 step provides in the most effectual manner for the safety of the men; besides, that the distance between the edge of the platform and the revolving wheel is by no means large enough for a man to fall through.

Mr. Hardie has likewise contrived a method of operating without a gibbet, in which he places 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 diminishes the swing of the goods in or out of the loop-hole, he has provided a sliding floor immediately under the floor of the ware

house, 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 sensible obstruction. Thus more than one man's labor in five or six is saved by getting quit of the friction of the pulley of a gibbet; and a still greater saving of labor is effected by accelerating all the movements at the loop-holes.

Mr. Hardie's lowering regulator is invented for the special purpose of removing the evils and dangers attendant upon the usual practice of lowering goods by the brake and brake-wheel. The part essential to this invention is a cast-iron box, fixed firmly to a floor, and divided into two cylindrical compartments; each ten inches long, one of four inches diameter, and the other of two inches diameter: these are both filled with oil, a liquid not subject to any material change by frost; or they may be filled with water in summer and mild weather, and some spirituous liquor (gin for instance) in frosty weather. These two cylinders communicate by apertures at their top and bottom; the smaller compartment having a cock with its axle passing through the side of the iron box, guarded by a stuffingbox, and a quadrant with equidistant notches fixed at its end, to receive an iron claw which retains the cock in any proposed situation, and shows the extent of its apertures when opened. The larger compartment has a piston, with its rod passing through the top of the iron box (guarded here also by a stuffing-box), and passing through a guide; this rod is connected with a joint moved by a crank, which is turned by a pinion of about six teeth, and this pinion is moved by a wheel of a size suited to the diameter of the barrel of the crane, and the weight of the goods commonly lowered: this latter wheel is fixed to the axle of the crane by a simple mode of connexion, which admits of its being disengaged during the operation of raising; it is also provided with the barrel-rope and counter-weight, which are commonly used for the purpose of winding up the slack crane-rope on the barrel of the crane, to be ready to repeat the operation of lowering.

Now if the cock were quite shut, the oil or other liquid confined between it and the piston would prevent the piston from moving, and of course hinder the goods hanging from the wheel, &c, connected with the pinion from descending: but, if the cock were opened a very little, the oil would pass slowly through it, and would therefore allow the piston to move up and down slowly, and the goods to descend slowly also; and in like manner a farther opening of the cock, will permit the load to descend with a greater velocity; thus the cock, by being more or less opened, gives the precise velocity desired to the descent of the goods, whatever their weight may be. The dvantages resulting from these inventions are too obvious to require our dwelling upon them. Although the crane is a walking-crane, yet it is free from the dangers and disadvantages of the common walking-wheel; for as the men

walk on the outside of the wheel instead of inside of the rim, they are, in consequence of the adjoining platform, and the use of the pawl, free from danger; while, during the whole time of their labor, they can walk in an upright posture, well suited to free respiration; and farther, as they act at the extremities of horizontal levers, their weight and occasional muscular force act with all the advantages they can have; while the modifications they can make at pleasure in their action, will frequently supersede the necessity of calling in any more men, even when a double load is to be raised. Indeed, there can be no doubt that with a crane of this construction, any given number of men will raise at least twice as much in a day, as they could in a common walking wheel, or working at a capstan, or at a wheel and pinion. And as to the lowering apparatus, it possesses a much higher degree of perfection in lowering than any of the other cranes. The means afforded of regulating it to lower either small or great weights with facility, expedition, and safety, and without depending during the operation on the precarious attention and management of a man, render it in our opinion far preferable to the hazardous and limited mode of lowering goods by the brake; while, with respect both to safety and great saving of labor, it obviously surpasses the modes of lowering by the capstan and the walking-wheel, which require nearly the same number of men to lower that they take to raise any weight.

It appears that Mr. Ferguson, the late popular lecturer on mechanics, first suggested the application of the vertical rollers above the axis or upper gudgeon of the jib. These ought so to be placed, that, if the rope be stretched close by their outermost sides, the half thickness of the rope may be perpendicularly over the upper gudgeon of the jib; for then the length of the rope, between the pulley in the jib and the axle of the great wheel of the machine, will be always the same, in all positions of the jib; and the jib will consequently remain in any position to which it may be turned; and they thus let the rope bend upon them as the jib is turned to either side. Almost all the jibs of the London warehouse cranes are constructed in this manner, the wheel-work being in the interior of the premises.

A useful crane, connected with the action of a capstan is in much use; and has been thus described. At the extremity of a beam, supported horizontally ten or twelve feet from the ground, is the upper pivot of a jib supported, the lower pivot resting on a post fixed in the ground. The jib is formed of a triangular frame and perpendicular sides, moving upon pivots on a vertical axis of motion. At an angle of about 90° or upwards, a beam is projected from near the upper end of the perpendicular part of the jib, and forming the upper side of the triangle. The third side is formed by a strong brace projected from near the foot of the perpendicular post, towards the extremity of the upper beam. From this extremity the weight is suspended by a rope passing over a pulley: the other end of the rope is wound round a vertical roller or capstan turning on pivots, one of which