or CAPSTERN, a strong massive column of timber, formed like a truncated cone, and having its upper extremity pierced with a number of holes to receive the bars or levers. It is let perpendicularly down through the decks of a ship, and is fixed in such a manner, that the men, by turning it horizontally with their bars, may perform any work which requires an extraordinary effort.

The following descriptions present a view of some important improvements on capstans by Captain Phillips of the royal navy.

Fig. 1 is an elevation of the upper capstan and works, and an elevated section of the lower capstan, of a frigate; A, the upper capstan, is fitted securely to the spindle by two iron crosses at the upper and lower ends of the barrel; B, the spindle, runs the full length of both capstans, is a fixture to the upper one, and revolves freely on turned bearings in the lower capstan; CC, a strong hexagonal plate, fitted to the spindle and upper part of the trundle-head. DD, the trundle-head, fits hexagonally over the barrel U, which is connected with the spindle by the plates CC and EE; the trundle-head is further secured by being bolted to the plate EE. By using a barrel instead of a plain trundle-head, a greater bearing is obtained upon the spindle, which must prevent the head from working, when the men bear much at the outer end of the bars. EE, the trundle-head lower plate, is fixed to the hexago- nal part of the spindle, and to the trundle-head, as above described. FF are fixed bolts that connect the plates C and E together; GG, drop-bolts, that serve either to attach the trundle-head to, or detach it from, the lower body. The size of the bolts is larger in diameter than the largest mooring chain of a line-of-battle ship; and from there being three in use, there can be no risk of their breaking. H is an hexagonal part of the spindle, on which the plates C and E fit, as well as the barrel U. II, the upper plate of the lower body, secures the body and whelps together. It has a circular hole in the centre, through which the spindle passes; the bearing is bushed with brass. KK, the lower body, is composed of a barrel, whelps, and pecul-head, like any other capstan, but revolving in turned bearings round the spindle. LL, drop bolts, which attach the lower body to the frame that carries the works, or detach it from them, as may be required, by means of chains running over the upper cheek. MM, the lower plate of the body, revolves with a turned bearing round the spindle. NN, the frame that carries the centre of the intermediate pinions NNN, which frame revolves in turned bearings round the spindle. O, the centre pinion, is fixed to the spindle. PP, the large wheel, is a fixture to the beams. Q, a collar, is bolted to the spindle on which the lower body rests. R, a col- lar to support the frame U. S, the step, is a strong piece of wood passing from beam to beam; it is secured by bolts to the beams, and supported by stauncheons from the deck; an iron cup with a brass bushing is let into it, to receive the lower end of the spindle. Fig. 2 is a plan of the works used in fig. 1, which shows that the centre wheel is but one half the size of the exterior wheel, although possessing a power of three to one. The parts of the works are lettered similar to those of fig. 1, being a plan corresponding with that elevation.

Fig. 3 is a plan of the works in fig. 4, the parts being lettered the same, and answering to the elevation described in fig. 4.

Fig. 4 shows the elevation of the upper capstan, with the works partly in section partly in elevation, and an elevated section of the lower capstan of a frigate. A, the upper capstan, is firmly secured to the spindle by crosses and an iron bolt. B, the spindle, which runs the length of both capstans, is a fixture to the upper one and false head, but revolves freely in the lower capstan. C, the false head, is attached to a hexagon on the spindle; it may be let on in halves, and when fixed to the spindle will prevent the lower capstan from rising. D, the lower capstan, is made entire; head, whelps, body, and pecul-head, similar to any other capstan, but revolving in turned bearings round the spindle. E, the collar that carries the lower capstan. F, the partners, are made like those of plain capstans, with iron spindles, with a cup let in to receive the toe. G, drop bolts, which serve to connect or disconnect the false head to the lower capstan. H, the standards, are secured at their base to the trundle-head, and on their upper end is fixed a circular ring, which supports the centres of the intermediate pinions NNN; which ring is attached by pillars to the upper flanch NN, with the pinions working between the plates NN. O, the centre pinion, is let on the hexagonal part of the spindle, and is consequently a fixture to it. Q, Q, the guides, are iron carriages, that are secured to the beams, and in which the bolts RR traverse. R, R, the bolts which serve to fix the large wheel when the increased power is in use, by grooves in stubs, fixed at opposite diameters of the rim of the large wheel. These bolts slide backwards and forwards in the guides, QQ. SS is a blocking of wood attached to the beams to support the carriages of the bolts RR. TT are the upper and lower deck beams, shown in section.

Fig. 5 is an elevation of the lower capstan of a frigate, with the spindle separated beneath the quarter-deck, and is constructed in every way similar to fig. 1, excepting that the trundle-head is connected to the body and whelps, and plays loosely round the spindle. A fixed head or plate, firmly secured to the spindle, attaches the lower capstan to the spindle by the upper deck bolts GG; it will therefore be only necessary to describe those parts that differ from fig. 1. CC, the false head, is secured to the spindle on an hexagonal bearing; D, the trundle-head, is a fixture to the lower body. The bolts GG and LL will be correspondent in strength to the spindle.

The mode of using these capstans will be more fully understood by referring to the letters in the plate and description.

When the upper bolts GG in fig. 1 are down, and the lower ones LL are suspended by the chains to the upper cheek, the capstan has no power beyond the leverage of the bars, as the works are totally disconnected with the capstans. To increase the power, elevate the bolts GG, and let the chains loose that suspend the bolts LL, when these bolts will fix themselves by their weight in the frame NN, and thus connect the lower body with the works. By the upper bolts GG being elevated, the lower body becomes detached from the head; and in this state, when the upper capstan is hove round, the lower capstan receives its motion by the bolts LL through the medium of the works. The lower head D, being a fixture to the spindle, has the power of setting the works in motion, as well as the upper capstan, and consequently the power may be acted upon on either deck. When all the bolts are up, the capstans are separated; the lower capstan will then remain stationary, and the upper capstan may be used to spring the ship, or for any other distinct purpose, whilst the messenger may remain during this period passed round the lower capstan body, ready to weigh the anchor.

In fig. 4 the works are between the quarter-deck beams. To increase the power, lock the large wheel P (that is, secure it by the bolts RR), and disconnect the false head CC from the lower capstan by elevating the bolts GG. Heave round on the quarter-deck capstan, and the power will be in action by the lower capstan being set in motion by the pillars HH through the medium of the works. To use it as a plain capstan, unlock the large wheel by withdrawing the bolts RR, and dropping the upper bolts GG, when both capstans and the works will traverse round together. To disconnect the capstans (that is, to use them for separate purposes), suspend the bolts GG and withdraw the bolts RR; when the works will go round with the lower capstan by means of the pillars HH, and the spindle with the upper one.

In fig. 5 the false head is a fixture to the spindle, and the lower capstan revolves round it. To increase the power, elevate the bolts GG, and drop the lower bolts LL. To use the capstan for separate purposes, lift all the bolts and keep them suspended; to make it a plain capstan, suspend the lower bolts LL, and keep the upper ones GG down.

The improvements above described consist in adapting an arrangement of wheel works to the capstan, to assist it with an increase of power when the power of the plain capstan is found to be insufficient. The arrangement of fig. 1 is similar to that which has been in general use in his majesty's service for these last ten years, and many instances have presented themselves during this period of the great benefit to be derived from the improvement. Among these, it will be sufficient to enumerate the essential use of which it proved to Sir Edward Parry, and all the later expeditions fitted out from this country for the purpose of maritime discovery; to the Diamond frigate, commanded by Lord Napier; to the Isis, by Sir Thomas Staines; to the Pelorus, by Captain Quin; to the Jupiter in the Gulf of St Lawrence; to the Druid and Aetna, commanded by Captain Sandon; and to the Tamar, by Captain Bremer.

The wheel work is so arranged that the power may be applied or relieved from it almost instantaneously; and the leading feature of the improvement is, that both capstans traverse the same way, either as a plain capstan, or when set in motion by the machinery; and the increase of power obtained is in the ratio of one revolution of the first mover more than the revolution gained by the difference of diameter between the first period and the large wheel. This is gained by making the large wheel stationary, and the centres of the intermediate pinions the means of communication with the capstan. Captain Phillips' capstans are so generally adopted in his majesty's service, that there have been more than two hundred and sixty-five supplied to all classes of his majesty's ships, besides those employed in foreign men-of-war and the East India and merchant service.