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a patent which is now expired for an excellent thrashing machine.In Plate CLXXV. tig. 1, represents the plan of elevation, fig. 2,the ground-plan, and fig. 3, shews its essential parts, so as to con-vey a tolerable idea of its principle. The large spur-wheel A,fig. I and 2, which has 276 cogs, is horizontal, and moves the pi-nion B, which has fourteen teeth. The pinion B moves thecrown-wheel C, which has 84 teeth, the wheel C moves a secondpinion D, which has 16 teeth: amt the pinion D moves the drumHIKL. The drum is a hollow cylinder three feet and an halfdiameter, and placed horizontally; on the outside of which thescutchers are fixed by strong screw-bolts. The scutchers consistof four pieces of wood, faced on one side with a thin plate of iron,placed at an equal distance from each other, and at right angles tothe axis of the drum. The sheaves are spread on an inclinedboard F, (fig. 3,) from which they are introduced between twofluted rollers GG, made of cast iron, about three inches and anhalf in diameter, and making about 35 revolutions in a minute.As these rollers are only about three quarters of an inch distantfrom the scutchers or leaves of the drum I11KL, they serve tohold the sheaves fast, while the scutchers a, b, c, d, moving withprodigious velocity, separate the grain completely Irom the straw,and at the same time throw out both grain and straw upon theconcave rack M, lying horizontally with slender parallel ribs, sothat the corn passes through them into a hopper N, placed below.From the hopper it passes through a harp or riddle O into a pairof fanners P, from which in the most improved machines, it comesout clean and fit for market. The straw, after being thrown bythe scutchers a, b, c, d, into the rack, is removed from it by arake QRST into a place contiguous V. The rake consists of fourthin pieces of wood or leaves; on the end of each of these leavesis ranged a row of teeth, c, f, g, h, five inches long. Tne rakemoves in a circular manner in the concave rack, while the teethcatch hold of the straw, and throw it out of the rack. These areall the essential parts of the machine; the rest may be easily un-derstood by the references to the Plate. W is the horse-course,(fig. 1,) which is 27 feet dfameter. X is the pillar for supportingthe beams on which the axle of the spur-wheel is fixed. YY\are three spindles for moving the two fluted rollers, the rake, andfanners. 2, (fig. 1,) is a wooden covering at a small distanceabove the drum, for the purpose of keeping the sheaves close tothe scutchers. Mr. Meikle’s thrashing-machine may be workedwith equal effect by horses, by water, or by the wind. If thefirst of these mechanical powers be employed, the whole, we un-derstand, costs about 70 1. in the second case, it amounts to about801. on account of the additional expence of the water-wheel ;and, if the thrashing-machine is to be turned by the wind, it can-not he erected for a less sum than from 200 1. to 300/. sterling.Although such disbursement be, at first, very considerable, yetnumerous machines on this principle have lately been erected inScotland ; because they are eventually cheap, by saving the la-bour of men, and the keeping of horses. Six persons are requiredlo attend the thrashing mill ; and, though a similar number beemployee) with the flail, and lor clearing an equal quantity of cornfrom chaff, yet by the former method, the work is more cleanlyand expeditiously performed. The advantages that may be de-rived from Mr. Meikle’s ingenious contrivance, are too obviousto require an enumeration ; we shall therefore only observe, (hatthe drum makes 300 revolutions in one minute, and the fourscutchers give 1200 strokes in the same space of time: conse-quently, much work must be executed from such velocity ; and,if the horses walk at the rate of two miles and a half every hour,from three to six bolls, (or from twelve to twenty-four English bushels,) will be thrashed every hour. Thus, the grain is notonly separated in a more perfect manner than is practicable bythe flail, but a saving of thirty or forty per cent, is also obtainedin the expence of thrashing. In Plate CLXXV. fig. 4 and 5, isrepresented another machine for this purpose, lately invented byMr. James Wardrop of Ampthil, Virginiu. A. (fig. 4,) is thefloor, over which the flails are fixed. B, represents that part ofthe floor, on which the sheaves are laid; it is made of wicker-work, through which the grain falls, and is conveyed to the fan orscreen below ; the pivot of the fan is delineated at P, and is turn-ed liy a band from the wheel or wallower, D. C, C, C, is a thinboard raised round the floor, to prevent the wheat from beingscattered; and which is made shelving outwards, that the straw

may be raked off more easily. D, the wheel or wallower. £, thecrank-handle for turning the wheel. F, F, F, are the flails. G,G, G, levers or arms, to which flails are attached by means ofropes. II, II, IT, are teeth or catches for raising the arms. I, thepost, on which the wallower D, is fixed. K, K, the beam onwhich the levers rest ; being fixed by an iron-rod passing throughthem, and inserted into this beam. L, L, a check-beam, lo pre-vent the end of the arms from rising. M, a beam, into which theends of the flails are mortised. N, N, N, are fly-ends, weightedwith lead, but which are not necessary in a machine that is set inmotion hv horses. To render the operation of the machinerysomewhat more evident, we have annexed a partial view of it infig. 5. This figure represents the arms G, G, G, working in thekeeps, O, O, O, and also the manner in which those parts areconnected. The model from which these delineations have beenmade, was designed to be worked by two men : it was construct-ed on the scale of a twelve-foot flail, having a spring that requireda power of twenty pounds to raise it three feet high at the point.Tire teeth or catches are mortised into the shaft of the wallower,and placed round its circumference; so as to form an angle ofthirty degrees. These teeth catch the arms G, G, G, that raisethe flails, alternately : thus, the whole power, namely, twentypounds, acts upon three of the flails, when they are about tostrike : three others are two-thirds raised ; three more are elevatedone-third ; and the remaining three flails are at rest; so that thewhole weight to ire overcome amounts to 120 pounds. Mr.Wardrop directs the.arms to be arranged in such manner, that aline drawn perpendicularly from their lifting extremity, wouldextend to the middle of the flail: the ropes must be fixed some-what nearer towards the end, that a proper tangent may be ob-tained.

THREAD, a small line made up of a number of fine fibresof any vegetable or animal substance, such as flax,, cotton, orsilk ; from which it takes its name of linen, cotton, or silk-thread.

THREATENING LETTERS. Knowingly to send any let-ter without a name, or with a fictitious name, demanding:money,or any other valuable thing, or threatening (without any demand)to kill or fire the house of any person, is made felony without be-nefit of clergy. Any sending letters, threatening to accuse anyperson of a crime punishable with death, transportation, pillory,or other infamous punishment, with a view to extort from himany money or other valuable chattels, is punishable by statute30 Geo, II. c. 24, at the discretion of the court, with fine,imprisonment, pillory, whipping, or transportation for sevenyears.

THREE BROTHERS, three islands in the Indian Ocean ,Lon. 62. 25. E. Lat. 3. 44. S.

Three Brothers, three other islands, in the East Indian Sea.Lon. 108. 0. E? Lat. 10. 42. N.

TI1R1NAX, Small Jamaica Fan-Palm; in botany, a ge-nus of plants of the natural class palm®, and order slabellifoli®.Calyx sexdentate; no corolla; stamina six; stigma emarginate;berry one seeded. It lias but one species, a native of Jamaica .

Til RIPS, in entomology, a genus of insects belonging to theorder hemiptera Rostrum obscure, or so small as to be scarcelyperceptible ; antenna 1 filiform, as long as the thorax ; body slender*of equal thickness in its whole length; abdomen bent upwards;wings four, extended, incumbent upon the back of the insect,narrow in proportion to their length, and cross one another atthe same distance from their base. The tarsi of the feet arecomposed of only two articulations. There are eleven speciesmentioned bv Gmelin.

THROAT. See Anatomy, Nf.ck, and Thorax .

'I’ll RONE, [ llironus , Lat. a chair of state, enrich-

ed with ornaments of architecture and sculpture, raised on oneor more steps, and .covered with a canopy. Such are thethrones in the rooms of audience of kings and other sove-reigns.

THRUMBEAP, a small circular island, in the South Pa-cific Ocean ; a mile-in circuit. Lon. 139. 48. W. Lat. 18.35. S.

THRUSH, in ornithology. Sec Turdtjs.

Thrush , or Aphtha. See Aphthje, and Medicine.

TH BY ALLIS, in botany, a genus of plants belonging to )he

class