THE London JOURNAL OF ARTS AND SCIENCES. No. XIII. Recent Patents. To CAPTAIN JOHN NICHOL, (in the East India Service,) of West End, Hampstead, Middlesex, for an Improved Capstan, Windlass, and Hawse-roller. THE improvement here suggested, is applicable to three distinct machines: to the capstan, the windlass, and the hawse-roller. The improvement upon the capstan, consists of a method of shifting the whelps,* so as to enlarge or diminish the diameter of the barrel; and hence, in the one case, to increase the speed by which the cable. may be hove in, or in the other to afford a greater power. Plate 1, fig. 1, represents a single capstan, the whelps of which are capable of being shifted. Fig. 2, is a double capstan upon the same principle; and fig. 3, is also a double capstan, with a contrivance for attaching * The meaning of this word is explained in the subsequent part of our description. VOL. III. or detaching the two spindles; the relative letters refer to the same parts in each figure.-a, is the drumhead, with its mortices for the reception of the capstan-bars; the centre block of the drum-head having a square or hexagonal hole, to fit on to the square or hexagonal part of the spindle, b. c, is the upper whelp plate; d, the lower whelp-plate; e, e, e, the whelps, of which there are six. The object here proposed, is to shift the whelps to different distances from the spindle, by means of which, the diameter of the barrel may be increased, and consequently the facility with which the cable may be hove in, is increased also. The mode of shifting the whelps, is by sliding them in grooves, formed in the upper and lower whelp-plates, and being advanced equal distances from the spindle, are secured from sliding back by bolts passing through the plates behind the whelps. Mortice holes are to be provided in the whelp-plates, at certain distances from the spindle, for the purpose of receiving the stops or bolts above mentioned. The shifting of the whelps in the above manner, may be performed in the short space of one minute, without the least inconvenience. A provision is made for supporting the whelps, by means of arms to be bolted on to the spindle, as k, and fig. 4; but it is considered, that the whelps being made of castiron, and of a proper substance, will of themselves be found sufficiently strong to support any resistance that the cable may be calculated to bear. The advantages to be derived from thus changing the diameter of the barrel, will be evident from the following considerations. Five different powers are proposed to be obtained from the same capstan, for the purpose of giving facility to the heaving in of a ship's cable in every state of the weather, and under all circumstances of difficulty which may occur; and also of heaving a ship afloat, after having been aground; both which may be effected with a smaller number of men by this improved capstan, than have hitherto been required on such occasions. To shew the effect of the changes in the diameter of the barrel, we will suppose the whelps placed at the outer position, by which they form a diameter of four feet, and that the bars, or levers, extend sixteen feet from the circumference of the whelps or barrel. It is evident, the power will then be as four to one: sixteen the lever, divided by four, the diameter of the barrel gives that sum. Let the whelps be shifted from this to the second position, and they will then form a barrel, the diameter of which will be three feet; the bar and a portion of the drum-head, now becoming a lever of sixteen feet and a half, which, being divided by three, gives the power as five and a half to one. Let the whelps again be shifted to the third position, the diameter of the barrel will be two feet, and the bar and portion of the drum-head will become a lever of seventeen feet, which, divided by two, gives the power as eight and a half to one. Let the whelps be shifted once more, the backs of them now resting against the spindle, the diameter will be one foot, and the bar and portion of the drum-head a lever of seventeen feet and a half; consequently the power will be as seventeen and a half to one. Lastly, in a case of great emergency, such as heaving a ship afloat that has been driven ashore in a gale, the whelps may be removed, and the spindle, b, of six inches diameter, used as a power which will be as thirty-five and a half to one. This sum being divided by four, the power of one man at the extremity of the bar in the first instance, gives nearly nine, That is, one man with the last mentioned power, is equal to nine men with the first; or, as one man at a common capstan, of four feet diameter, with a bar or lever one hundred and forty-four feet in length. From the foregoing description, it is evident that the different powers of this capstan, are obtained without any increase of friction, which is unavoidable where compound machinery is used, and the number of parts in contact consequently increased. The quantity of cable hove in by each revolution of the capstan, will depend on the position of the whelps, which, at the outer situation, will be two fathoms; at the second, one fathom and a half; at the third, one fathom; at the fourth, three feet; and at the spindle, one foot and a half which shews that the less mechanical power with which the object can be accomplished the better; as time must inevitably be lost in proportion to the power gained. It is, therefore, an important feature of this capstan, that time need not be lost unnecessarily, as its power may, even during the act of heaving up the anchor, (by shifting the whelps outwards or inwards,) always be proportioned exactly to the resistance that is to be overcome; from which circumstance, it is presumed that the improved capstan will be found more useful than any capstan that bas hitherto been invented; besides which, its cost will be less than the ordinary sort of common capstan. If a single capstan be constructed upon this principle, the spindle will, of course, be in one entire length, as fig. 1; and the lower whelp-plate must be furnished with pauls, fixed in the usual manner. When a double capstan is required, it may be constructed upon this principle with a spindle of one entire length, also as fig. 2; the two capstans acting together, pauls will then only be necessary to the lower one. But if two capstans are, at times, required to work, independently of each other, the spindle |