a very common little instrument or utensil, made of steel, pointed at one end, and pierced at the other, used in sewing embroidery, tapestry, &c.

Needles make a very considerable article in commerce, though there is scarce any commodity cheaper, the consumption of them being almost incredible. The sizes are from No. 1. the largest, to No. 25. the smallest. In the manufacture of needles, German and Hungarian steel are of most repute.

In the making of them, the first thing is to pass the steel through a coal-fire, and under a hammer, to bring it out of its square figure into a cylindrical one. This done, it is drawn through a large hole of a wire-drawing iron, and returned into the fire, and drawn thro' a second hole of the iron, smaller than the first; and thus successively from hole to hole, till it has acquired the degree of fineness required for that species of needles; observing every time it is to be drawn, that it be greased over with lard, to render it more manageable. The steel thus reduced to a fine wire, is cut in pieces of the length of the needles intended. These pieces are flattened at one end on the anvil, in order to form the head and eye: they are then put into the fire, to soften them farther; and thence taken out and pierced at each extreme of the flat part on the anvil, by force of a puncheon of well-tempered steel, and laid on a leaden block to bring out, with another puncheon, cheon, the little piece of steel remaining in the eye. The corners are then filed off the square of the heads, and a little cavity filed on each side of the flat of the head; this done, the point is formed with a file, and the whole filed over: they are then laid to heat red-hot on a long narrow iron, crooked at one end, in a charcoal fire; and when taken out thence, are thrown into a basin of cold water to harden. On this operation a good deal depends; too much heat burns them, and too little leaves them soft; the medium is learned by experience. When they are thus hardened, they are laid in an iron shovel on a fire more or less brisk in proportion to the thickness of the needles; taking care to move them from time to time. This serves to temper them, and take off their brittleness; great care here too must be taken of the degree of heat. They are then straightened one after another with the hammer, the coldness of the water used in hardening them having twisted the greatest part of them.

The next process is the polishing them. To do this, they take 12,000 or 15,000 needles, and range them in little heaps against each other on a piece of new buckram sprinkled with emery-dust. The needles thus disposed, emery-dust is thrown over them, which is again sprinkled with oil of olives; at last the whole is made up into a roll, well bound at both ends. This roll is then laid on a polishing table, and over it a thick plank loaded with stones, which two men work backwards and forwards a day and a half, or two days, successively; by which means, the roll thus continually agitated by the weight and motion of the plank over it, the needles withinside being rubbed against each other with oil and emery, are infensibly polished. After polishing, they are taken out, and the filth washed off them with hot water and soap; they are then wiped in hot bran, a little moistened, placed with the needles in a round box, suspended in the air by a cord, which is kept stirring till the bran and needles are dry. The needles thus wiped in two or three different brans, are taken out and put in wooden vessels, to have the good separated from those whose points or eyes have been broke either in polishing or wiping; the points are then all turned the same way, and smoothed with an emery-stone turned with a wheel. This operation finishes them, and there remains nothing but to make them into packets of 250 each.

Dipping Needle, or Inclinatory Needle, a magnetic needle, so hung, as that, instead of playing horizontally, and pointing out north and south, one end dips, or inclines to the horizon, and the other points to a certain degree of elevation above it.

The dipping-needle was invented in the year 1576, by one Robert Norman a compass-maker at Wapping. The occasion of the discovery, according to his own account was, that it being his custom to finish and hang the needles of his compasses before he touched them, he always found, that immediately after the touch, the north-point would bend or incline downward, under the horizon; inasmuch that, to balance the needle again, he was always forced to put a piece of wax on the south-end as a counterpoise. The constancy of this effect led him at length to observe the precise quantity of the dip, or to measure the greatest angle which the needle would make with the horizon; and this at London he found to be $71^\circ 50'$. In 1723 Mr Graham made a great many observations on the dipping-needle, and found the angle to be between 74 and 75 degrees. Mr Nairne, in 1772, found it to be somewhat above $72^\circ$. It is not certain whether the dip varies, as well as the horizontal direction, in the same place. The trifling difference between Mr Forman and Mr Nairne, would lead us to imagine that the dip was unalterable; but Mr Graham, who was a very accurate observer, makes the difference more considerable. It is certain, however, from a great number of experiments and observations, that the dip is variable in different latitudes, and that it increases in going northwards. It appears from a table of observations made with the marine dipping-needle in a voyage towards the north pole, in 1773, that in lat. $60^\circ 18'$, the dip was $75^\circ$; and in lat $70^\circ 45'$, it was $77^\circ 52'$; in lat. $80^\circ 12'$, it was $81^\circ 52'$; and in lat. $80^\circ 27'$, it was $82^\circ 2\frac{1}{2}'$.

Several authors have endeavoured to apply this discovery of the dip to the finding of the latitude; and Mr Bond attempted to apply it to the finding of the longitude also; but for want of observations and experiments, he could not make any progress. The affair was farther prosecuted by Mr Whiston, who published a treatise on the longitude, and for some time imagined it was possible to find it exactly by means of the dip of the needle; yet he at last despaired of it, for the following reasons: 1. The weakness of the magnetic power. 2. The concussion of the ship, which he found it exceeding difficult to avoid so much as was necessary for the accuracy of the experiments. 3. The principal objection was an irregularity in the motions of all magnetic needles, both horizontal and dipping, by which they, within the compass of about a degree, vary uncertainly backward and forward; even sometimes, in a few hours time, without any evident cause. For a particular account of these variations both of the horizontal and dipping needle, see the article Variation.

Mr Nairne, an ingenious instrument-maker in London, made a dipping-needle in 1772 for the board of longitude, which was used in the voyage towards the north-pole. This is represented Plate CCIV. fig. 1. The needle AA is 12 inches long, and its axis, the ends BB of which are made of gold alloyed with copper, rests on friction-wheels CCCC, of four inches diameter, each end on two friction-wheels; which wheels are balanced with great care. The ends of the axes of the friction-wheels, are likewise of gold alloyed with copper, and moved in small holes made in bell-metal; and opposite to the ends of the axes of the needle, and the friction-wheels, are flat agates, set in at DDD, finely polished. The magnetic needle vibrates within a circle of bell-metal, EEE, divided into degrees and half degrees; and a line, passing through the middle of the needle to the ends, points to the divisions. The needle of this instrument was balanced, before it was made magnetic; but by means of a cross, the ends of which are FFFF, (contrived by the reverend Mr Mitchell) fixed on the axis of the needle, on the arms of which are cut very fine screws to receive small buttons, that may be screwed nearer or farther from the axis, the needle may be adjusted both ways to a great nicety, after being made magnetic, by reversing the poles, and changing the sides of the needle. GG are two levels, by which the line of 0 degrees of the instrument... Instrument is set horizontal, by means of the four adjusting screws L.L.L.L.; H is the perpendicular axis, by which the instrument may be turned, that the divided face of the circle may front the east or west; to this axis is fixed an index I, which points to an opposite line on the horizontal plate K when the instrument is turned half round; M.M.M.M are screws which hold the glass-cover to keep the needle from being disturbed by the wind. When this needle is constructed for sea, it is suspended by an universal joint on a triangular stand, and adjusted vertically by a plumb-line and button above the divided circle and the dovetail work at the upper go; and the divisions on the circle are adjusted so as to be perpendicular to the horizon by the same plumb-line, and an adjoining screw; and when it is adjusted, a pointer annexed to a screw, which serves to move the divided circle, is fixed at the lowest go. Whenever the instrument is used to find the dip, it must be so placed that the needle may vibrate exactly in the magnetic meridian.

Magnetical Needle, in navigation, a needle touched with a loadstone, and sustained on a pivot or centre; on which playing at liberty, it directs itself to certain points in or under the horizon; whence the magnetical needle is of two kinds, viz. horizontal and inclinatory. See the article Magnet.

Horizontal needles are those equally balanced on each side the pivot that sustains them; and which, playing horizontally with their two extremes, point out the north and south points of the horizon. For their application and use, see the article Compass.

In the construction of the horizontal needle, a piece of pure steel is provided; of a length not exceeding six inches, lest its weight should impede its volatility; very thin, to take its verticity the better; and not pierced with any holes, or the like, for ornament sake, which prevent the equable diffusion of the magnetic virtue. A perforation is then made in the middle of its length, and a brass-cap or head foldered on, whose inner cavity is conical, so as to play freely on a style or pivot headed with a fine steel point. The north point of the needle in our hemisphere is made a little lighter than the southern; the touch always destroying the balance, if well adjusted before, and rendering the north end heavier than the south, and thus occasioning the needle to dip.

The method of giving the needle its verticity or directive faculty, has been shewn already under the article Magnet; but if, after touching, the needle be out of its equilibrium, something must be filed off from the heavier side, till it balance evenly.

Needles in sea-compasses are usually made of a rhomboidal or oblong form: we have given their structure already under the article Compass.

The needle is not found to point precisely to the north, except in very few places; but deviates from it more or less in different places, and that too at different times; which deviation is called its declination or variation from the meridian. See the article Variation.

Needle-Fish. See Syngnathus.