studs, or other projections, to the bottom of a pan for supporting the meat, in whatever way the said bars, studs, or other projections may be applied.—[Inrolled in the Inrolment Office, October, 1839.]

TO THOMAS ROBINSON WILLIAMS, of Cheapside, in the city of London, gent., for certain improvements in measuring the velocities with which ships or other vessels or bodies move in fluids; and also for ascertaining the velocities of fluids in motion.-[Sealed 27th August, 1840.]

THIS invention consists in several different arrangements of apparatus, adapted to the various circumstances under which moving bodies have relation to the fluids in which they move.

The arrangements which apply particularly to ships, are first described for river navigation, where the cargo is not liable to great fluctuation in weight; and the perpendicular height of the vessel as regards the water line, evenness of keel, is less disturbed than in sea navigation.

A bent copper tube is used, (see Plate XVI.,) A, B, fig. 1, inserted either through the stern-post or keel, or by the side of either of them, and passed down the stern-post to near its heel; and then, being bent backward, that is, in a direction contrary to the bows or head of the vessel, and made to point rather below or under the rudder, projecting but a short distance from the stern-post, according to its size, and should be merely of sufficient length to be clear of the dead water;-behind the post or keel, this end is left open to the water. The inner end is then bent upwards through the floor of the room or cabin a, where a

float-bob, of light hollow glass or metal, with a rod b, attached, provided with a scale, similar to common guages for steam, &c.; or, when the water line is not inconveniently low, a strong glass tube is made to form the upper part of this tube, including the water line; that is, the point to which the water will rise when the vessel is not in motion; this then becomes the zero point upon the scale, and with whatever velocity the vessel sails in a forward direction, produces a partial exhaustion of the water from this tube, or a depression of its surface therein; and, consequently, indicates the speed with very great accuracy.

Attached to this main, is a bent glass tube, the two ends being upwards, and one of them connected with the main, the other open to the atmosphere. This bent tube, being partially filled with mercury, and having a scale attached, indicates the velocity by the surface of mercury, in the proportions of the weight of mercury to that of water. To remedy the inconvenience, however, on this principle of the fluctuations of the weight of cargo, a water cistern c, one, two, or three feet square, may be provided, and of sufficient depth; which (placed as near midships, and over the keel, as possible,) has small and safe external communications c, c, through the vessel, into which the water may flow in and out, that its surface may always correspond with the external water line. Within this box or cistern, another flat hollow metallic or other box d, is made to float, but so as to sink considerably below the surface of the before-mentioned cistern. Through the bottom of this float, is firmly soldered or fixed, either the single or bent tube, with its scale, connected by a flexible India-rubber tube e, with the before-mentioned main A, B.

Another apparatus to ascertain the velocity of ships, in sea or river navigation, whether by wind or steam, consists of an instrument, suspended by an universal joint in any

convenient part of the vessel, such as the companion-way, or captain's room, and a plummet or drag, or a drag chain, or line, &c., to be towed overboard, and attached thereto, as hereinafter described.

Fig. 2, is a view of the apparatus, with its outer case removed; and fig. 3, the various plummets or drags, used with this and the hereafter-described instruments. At fig. 2, A, is an iron cylinder or chamber, of about one and a quarter inch internal bore, and eighteen inches in length, connected by the small bent tube 1, with the glass tube B, which is cemented into the socket 2, with its upper end open to the atmosphere; c, the wood-work for supporting the internal parts; D, is a plunger, of hollow glass or other material, with the bottom end closed, and made to slide very freely in the iron chamber A; E, is the standard by which the whole is supported and secured to the woodwork of the room or cabin; F, a circular ring, within the arch 3, of the standard E, which, with the screw-pivots 4, 5, 6, and 7, form the universal joint for preserving the perpendicularity of the instrument.

In the standard E, is a finely-adjusted pulley 8,-and 9, another such pulley; 10, the cap of the plunger D, from which projects an ear or staple, to which a strong flexible silk cord is fastened, which passes over the pulley 9, and thence over the pulley 8; G, is the scale on which the knots per hour are graduated; o, is the zero point upon this scale, level with which line, and that intersecting 11, on the iron cylinder A, the mercury stands, when the plunger is in its place, and floating at liberty upon the surface of the mercury.

It will now be seen, that when the cord 12, is pulled, the column of mercury, in the glass tube B, as well as in that of a, will rise by the descent of the plunger, and con2 Q

VOL. XVIII.

sequent displacement of the mercury,—and this in an equal ratio, as the degree of tension is increased.

The drag, to be towed overboard, for occasioning the resisting power, (which resistance will always correspond with the velocity of the vessel,) and for operating upon the instrument, as represented by the line 12, 12, fig. 1, connected therewith, may be of various kinds as well as shapes.

For measuring currents or small velocities, and in shallow water, a plain braided rope, of 100 feet or more in length, and of the size of the common log-line, will answer the purpose, saturated with India-rubber, or other adhesive materials, to prevent wear. In other cases, a plummet of metal or glass, of the shape represented at A, fig. 3, may be used; if so, about half the length of line only is necessary.

A smaller line is recommended for sea practice, of about a quarter of an inch in diameter, and 200 feet long, having a number of conical or egg-shaped plummets of metal, glass, or ivory, upon it, at the extreme end from the ship, as represented at в, fig. 3. about three feet apart. Twelve of these, with a line of this length, at the speed of ten knots per hour, indicate six pounds avoirdupoise upon the pound and ounce scale of the instrument; or nine knots upon the scale of knots by the mercury. The pound and ounce scale is intended as a ready way of adjusting the instrument at all times, by proving it with such weights attached on shore.

By this means, the proper length of tow-line is readily ascertained for regulating the column of mercury to the scale and rate of sailing, by measured miles, of any vessel.

In what manner the connection between the towingdrag or plummets and the instrument is effected, depends upon where it is preferred to station and suspend the instrument, and from what part of the vessel to use the drags.

If it be hung in the cabin, as represented at D, fig. 1, (this being very convenient, on another account hereafter described, for shewing the trim of the vessel,) the plummets or drag should be worked from the stern; and, in order that the point of suspension of the cord or line 12, be as near the surface of the water as possible, a hole is bored through the stern, in a slanting direction downwards, as near the middle of the vessel as may be, but avoiding the rudder; and, to prevent the line rubbing against the sides of this hole, two pullies f,f, are inserted in the wood-work of the stern outside, one above and one below, to take off the friction from the cord.

It will be evident that this instrument, as well as the next described, is equally applicable for measuring the velocities of currents themselves, from vessels or boats, moored in rivers, rapids, raceways of mills, from bridges, or even from boats at sea;-where a heavy body is lowered to a great depth as a mooring, the strength and direction of a surface current may be easily ascertained.

At E, fig. 1, is shewn the manner in which this instrument is made to shew the trim of a vessel, the perpendicularity being always maintained by its manner of suspension. Immediately under it is placed a strong table g, g, having upon its surface a metal plate h, being horizontally secured when the vessel is in perfect trim, as to stem and stern, as well as crosswise, or otherwise, the best determined position for sailing. This plate has a centre point i, which is placed precisely under the index point, upon the instrument D, and which is as near the plate as possible without touching it. The plate is divided into lines, running at right angles with each other, one half longitudinally with the vessel, and the other at right angles thereto. lines or divisions are calculated to form degrees of a circle, (the length of the instrument, from its point of suspension

These