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to attend to that duty, when the performance is This will be better understood by referring to most necessary, namely, in a heavy gale, was fig. 5, which is a representation of this machine, put in practice with great success by captain and in which vu w x shows a flexible tube or Leslie, of the ship George and Susan, on a late pipe, wound in a screw-like form round a solid voyage from Stockholm io North America. He cylinder y y, the two extreme ends of which are fixed a spar aloft, one end of which was ten or equipped with pivots, so that the cylinder, with twelve feet above the top of his pumps, and the its encircling screw-formed tube, may be made other projected over the stern; to each end he to revolve on its axis by the force of running affixed a block, or pulley; he then fastened a water, or any other power applied to its upper rope to the spears of the pump, and, after passing or lower end. Lastly, this machine must be it through both pulleys along the spar, dropped supported by its two pivots, so as to make an it into the sea astern. To the rope he fastened angle with the horizon, as shown in the figure. a cask, 110 gallons measurement, and containing If now the lower end v of the tube be supposed sixty or seventy gallons of water. This cask to be covered with water, that water will flow to answered as a balance-weight, and every motion its own level within the tube, and will occupy of the ship from the roll of the sea made the the lowest bend v; and if now the cylinder, yy, machinery work. When the stern descended, or be turned round by its handle, in a direction when a sea or any agitation of water raised the from left to right, the lower end of the spiral cask, the pump-spears descended ; and the con tube will become elevated above the surface of trary motion of the ship raised the spears, when the water in the reservoir, and that water which the water flowed out. The ship was cleared out had entered into the tube will have no opporin a few hours, and the crew were of course tunity of escaping, but, by the motion of the greatly relieved.

screw-tube, will flow within it, until, at the end In the Persian wheel, water may be raised by of the first revolution, it will be found in the means of a stream d, piate IV. fig. 4, turning a second lower bend u. In the mean time the series of floats, and furnished with buckets a b, lowest extreme end of the tube will bave made suspended by strong pins fixed in the side of the a second dip into the water of the reservoir, and rim; but the wheel must be made as high as the will receive a second charge, which, in like water is intended to be raised above the level of manner, will be transferred to u, at the next that part of the stream in which the wheel is revolution, while the water lately at u will be placed. As the wheel turns, the buckets on the elevated to w; until at length, when the cylinone side descend into the water, and then go up der has made as many revolutions as there are full on the other; when they arrive at they turns of the tube round it, each lower bend will strike against the end of the fixed trough and become filled with water, whatever may be the are overset, and empty the water into the length of the cylinder yy; and as the extreme trough; from which it may be conveyed in pipes upper end a of the tube becomes depressed, in to the place where it is designed for; and, as each revolution, into the situation of a lower each bucket gets over the trough, it falls into a bend, it will there discharge its water into an perpendicular position again, and goes down elevated cistern b, placed to receive it. The empty, until it comes to the water at d, where it quantity of water raised by this machine will is filled as before. On each bucket is a spring, depend upon the capacity of the screw-pipe, and which, going over the top or crown of the bar, the angle above the horizon at which it is placed raises the bottom of the bucket above the level to work; but it will be seen by the figure, that of its mouth, and so causes it to empty all its there is room to dispose several pipes, parallel to water into the trough.

each other, round the same cylinder, when they Sometimes this wheel is made to raise water will all work simultaneously; or the whole no higher than its axis; and then, instead of cylinder itself may be made into a hollow screw, buckets hung upon it, its spokes are made of a by merely placing a thin screw-formed diabent form, and hollow within; these hollows phragm or partition round its central axis, which opening into holes on the outside of the wheel, is the most usual form of the machine in pracand also into those in the box upon the axis. tice. On a small scale, it may be constructed So that, as the holes dip into the water, it runs by wrapping one or more flexible lead pipes into them; and, as the wheel turns, the water round a solid cylinder of wood, which forms a rises in the hollow spokes, and runs out in a useful machine for raising water to small heights. stream from a series of holes, thus falling into It was formerly much used, but owing to its the trough, whence it is conveyed by pipes to its liability t become choked by mud, weeds, and destination.

other impediments, and the great difficulty of Nearly allied to the Persian wheel, but much cleaning it out, it is seldom met with. It has, more elegant in its contrivance, is the screw of from its specious appearance of seeming to Archimedes, a machine invented and used by throw the entire weight of water that it is raisthis philosopher, for raising water and draining ing upon its axles, and the little friction with land in Egypt, about 200 years before the Chris- which these may be made to move by frictiontian era. The cochlion consists of a succession rollers, had astonishing powers ascribed to it; of huckets or recesses to be filled with the water but, if investigated, it will be found that the to be raised; but instead of their being sepa water is merely made to flow up an inclined rate and detached, as in the Persian wheel, they plane; and whether water or any other weight are formed by the lower parts of the hollow be drawn up a fixed inclined plane, or it be thread of a screw, and their motion and succes- stationary until noved by an inclined plane sion are brought about by turning that screw. being forced under it, as is the case with the

quantities of water contained in the several bends so that water issuing from them may spout horiv, u, w, x, &c., the mechanical effort will be the zontally and in opposite directions, as shown at same; consequently, this machine possesses no the letters 7 and a. One end of a pipe B comother mechanical advantage over other construc- municates with a supply of water which it delitions of pumps, except that its motions are vers into the funnel head v without touching it attended by less friction than belongs to most of in any part, and the supply of this pipe must be them.

so regulated by a cock or otherwise, that it may The rope-pump of Vera, described in most constantly keep the pipe u v filled with water books on hydraulics, consists of an upper and without running over, at the same time that the lower pulley, formed in the ordinary manner, discharge is going on from the orifices 2 a, which but with several grooves in each, in which end- will deliver their water with a force proportionless ropes of very loosely spun horse-hair or ate to the perpendicular height of the column of wool are made to move with great rapidity by a water contained in u v; and, since the holes za multiplying wheel connected with the upper are in opposite directions, the water in passing pulley. The lower pulley, together with a great from them will meet with such a resistance from part of the rope, moves in the water, which is the surrounding air as to throw the pipe u v, with merely brought up by adhering to the ropes, and its arms and axis x, into rapid roratory motion, the rapidity of their motion. This, therefore, is and this axis may communicate its motion and but a very imperfect and rude kind of bucket- power to wheel-work or machinery, or even to a pump, and is by no means deserving the place mill-stone connected with its upper end. This it has so long held in the catalogue of hydraulic machine is described and highly spoken of in machines.

almost all the books that teach of hydraulic maSarjeant's pump may be considered as a cheap chinery, but it does not appear to have been and useful prime mover. It was originally ap- carried into practical effect in England. plied to the raising of water at Irton Hall; and The centrifugal pump may be considered as a small stream in the neighbourhood was bearing some resemblance to Barker's Mill inbrought by a wooden trough, into which was verted, as the water in this case rises up the inserted a piece of two-inch leaden pipe, a part tube A A fig. 8, plate IV., from the reservoir E, of which is seen at A, plate 4, fig. 6.

and is thrown off by the centrifugal force at the The stream of the pipe is so directed as to run ends of the lateral branch BC. This branch is into the bucket B, when the bucket is elevated; furnished with valves at the extremities; and, a. but so soon as it begins to descend, the stream quantity of water having been poured into the flows over it, and goes to supply the wooden lower vessel E, the cylinder and the lateral trough, or well, in which the foot of the forcing- branch are also filled with water. The appapump C stands, of three inches bore.

ratus is then put into motion by turning the D is an iron cylinder, attached to the pump handle at G, and the centrifugal force driving rod, which passes through it. It is filled with out the valves at the extremities of the branch, lead, and weighs about 240 lbs. This is the the water rushes rapidly into the trough D, from power which works the pump, and forces the which it returns into the reservoir through a water through 420 feet of inch pipe, from the hole at f. The water at the same time rises pump up to the house.

through a valve, at the bottom of the tube A A, At E is fixed a cord, which, when the bucket opening upwards. comes to within four or five inches of its lowest The Water Ram, or Bélier Hydraulique, as it projection, becomes stretched, and opens a valve was called by its inventor, M. Montgolfier, of in the bottom of it, through which the water Paris, is a highly useful and simple machine, for empties itself.

the purpose of raising water without the expenThere is another machine for the purpose of diture or aid of any other force than that which procuring motion and power by water, which is produced by the momentum or moving force was invented by Dr. Barker towards the close of a part of the water that is to be raised; and of the last century, and which is generally known is one of the most simple and truly philosophical by the name of Barker's Centrifugal Mill. Its machines that hydraulics can boast. The action general construction is shown at fig. 7, plate IV., of this machine depends entirely upon the moin which vu is a metal pipe of considerable mentum that is generated whenever a body is height, its top v being widened or extended into put into motion, and its effect is so great as to a funnel shape. The pipe is maintained in its give the apparatus the appearance of acting in vertical position, as shown in the figure, by defiance of the established laws of hydrostatic resting on a pointed steel pivot turning into a equilibrium; for a moving column of water of brass box w at the lower extremity, while the small height is made to overcome and move anupper part has a cylindrical steel axis passing other column much bigher than itself. through the top y y of a frame which supports The form and construction of the water-ram it: the pipe vu is consequently free to move is shown at fig. 9. Suppose o to represent a round upon its own axis, which it does with cistern or reservoir, or the source of a spring very little friction. Towards the lower extre- which is constantly overflowing and running to mity of the pipe v u, and at right angles to its waste, by means of a channel a few feet lower axis, two or more smaller pipes or arms with than itself, as at the level line pp. Instead of closed external ends are inserted as at 2 a, and permitting the water to run over the sides of o, an adjustable orifice is made at the side of each let it be conducted to the level line p p, hy of these small pipes as near as possible to its means of iron or other pipes 9 q connected with end, and placed on opposite sides of such pipes, the side of the reservoir, and terminating by an

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orifice r', in which a conical or other valve s is wise depend on the same circumstances. A very placed so as to be capable of effectually closing insignificant pressing column o'v is capable of the pipe when such valve is drawn upwards; raising a very high ascending column u I, so t is an adjustable weight fixed on to the spindle that a sufficient fall of water may be obtained in of the valve s, hy means of which the valve is almost every running brook, by damming up its kept down and open; any water therefore that upper end to produce the reservoir and

carry is in the cistern o will flow down the pipe 99, ing the pipes 9 9 down the natural channel of and escape at the orifice r, so long as the valve the stream until a sufficient fall be ohtained ; remains down, but, the instant it is raised and for a considerable length of descending pipes shut, all motion of the water is suspended. from o to r is necessary to insure the certain Thus situated, the adjustment of the weight t effect of the machine, since, if the column qe must take place, and, by adding to or subtracting is not of sufficient length, its water will be thrown from it, it must be made just so heavy as to be back into the reservoir, instead of entering the capable of sinking or forcing its way down- air-vessel, which requires to be replenished with wards, against the upward pressure of the water, air, and this is admitted into it by the self-acting the force of which will depend upon the per- shifting valve, shown at b in the shaded part pendicular distance from the surface of the water it, which is an enlarged view of the air-vessel in o, to its point of discharge at (represented in an improved form; its valve is made by a by the dotted line ov). But the water by mov ball at a, having a metal bridle over it to prevent ing acquires momentum and new force, and its rising too high. consequently is no longer equal to the column In taking the height to which water is to be o v, to which the valve has been adjusted, but raised by a pump, perpendicular height alone is is superior to it, by which it is enabled to over to be regarded, and not lateral extension, because power the resistance of the weight t, and it car fluids

press according to their perpendicular ries the valve up with it, and closes the orifice r. height. Thus, if a pipe 100 feet long is six This is no sooner done than the water is con feet higher at one end than at the other, the six strained to become stationary again, by which feet only are to be regarded as the height to the momentum is lost, and the valve and weight which the water must be raised, and the 100 feet once more become superior, and fall, thus re- may be disregarded, except so far as it produces opening the orifice and permitting the water to friction detrimental to the motion of the water. move again; and, as the pressure of the water The height of a lift of water must be taken from and the weight of the valve each become alter- the surface of the water which is to be listed to nately superior, the valve is kept in a constant the surface of the cistern, or reservoir, or end of state of vibration, or of opening and shutting the pipe that is to receive or deliver it, and not without any external aid, whatever. Such is the from the bottom of the suction-pipe, because that principle upon which the motion of the water pipe may descend any distance below the surface in the pipe qq is produced : but the momentum of the water to be raised without affecting the generated cannot be instantly annihitated; and measurement, since the water will always rise to it is not only of sufficient power to raise the its own level within that pipe, without the aid valve s, but likewise to burst open the lower of any exertion of force by the pump. Be careend of the pipe 9.9, unless a sufficient vent be ful, likewise, to introduce no right-angled or provided by which this accumulated force can short turns into pipes, if they can be avoided; escape. Accordingly a second valve u is placed but let every such turn be a regular curved near the lower end of the pipe 9 9, and is made sweep, and the larger and more regular that to open upwards into an air-vessel, having a dis-, sweep is made, the less impediment it will offer charging pipe r; and consequently, whenever to the passage of the water. the valve s is closed, the water, which otherwise In order to determine the force or power would have flowed from the orifice 1, now opens necessary to work a pump of any description, the valve u and enters the air-vessel, until the the height to which the water is to be raised must spring of the contained air overcomes the gradu- always be taken into account; for this height ally decreasing force of the momentum, when multiplied into the area of the piston, and rethe valve u closes, and that at s opens to permit duced to any of the usual denominations of the water to make a second blow or pulsation, weight, will give the amount of resistance to be and in this way the action of the machine con overcome (friction of the pump only excepted). tinues unceasingly without any external aid so The size of the pipe containing the water is quite long as it is supplied with water, and remains in immaterial, provided it be large enough to prerepair. A small running stream is necessary for vent friction and unnatural velocity in the water; this machine, as the water at o should be kept at and the entire perpendicular height from the one constant elevation to ensure the perfection surface of the water raised to the point where of its action. A much greater quantity of water it is delivered, whether occupied by suction likewise escapes at the orificer, between the or feeding-pipe, or delivering pipe from a forcing pulsations, than can be raised in the delivering pump must be added together, and considered pipe I, particularly if it extends to any con as the height of the lift : so that if a list and siderable' height; for the comparative quantity force-pump of four inches in diameter, in the of water discharged through r, and permitted to working-barrel, has ten feet of three-inch suce run to waste at r, must always depend upon the tion-pipe below its piston, and twenty feet of respective perpendicular heights of the pressing two-inch delivering-pipe (including the length of column o v, and the delivered or resisting column the working-barrel) above it, the column to be u 1, and the rapidity of the pulsations will like lifted will be equal to thirty feet of four-inch

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pipe filled with water. The contents in gallons standard for pipes of any other size, by observing of thirty feet of four-inch pipe must therefore be the following found, and, as each imperial gallon of water Rule.-Multiply the numbers found in the weighs 10 lbs. avoirdupois, the weight or load table against any height by the square of the upon the pump will be immediately found, to diameter of the pipe, and the product will be the which must be added from one-tenth to one number of cubic inches, avoirdupois ounces, and sixth, according to the construction of the pump, wine gallons of water, that the given pipe will for friction. The load upon an eccentric or any contain. other pump may be found by the same rule, if Erample.—How many wine gallons of water the effective horizontal area of the piston, or its are contained in a pipe six inches diameter, and substitute, be found; and this be in like man- sixty feet long :-ner multiplied into the height of the lift. It 2.4480 X 36 = 88:1280 wine gallons. therefore becomes important to know the weight The

The wine gallon contains 231 cubic inches, and quantity of water which a certain length of

and the new imperial gallon 277.274 cubic pipe of any given diameter will contain, and a

inches; therefore, to reduce the wine to the imtolerably close approximation to this may be ob

perial gallon, divide by 1.20032; and for a like tained by squaring the diameter of any pipe in

reduction of the ale gallon, which contains 282 inches, and cutting off the last figure of the cubic inches, divide by 0.98324. product by a decimal point, which will nearly HYDROSULPHURETS. Compounds of give the contents in ale-gallons of one yard in

.." sulphureted hydrogen with the salifiable bases. length of such pipe. Thus, for example, if a HYDROTHIONIC ACID. Sulphureted hypipe is six inches in diameter, 6 times 6 make de

drogen, the hydrosulphuric acid of M. Gay 36, and introducing the decimal point would re

Lussac. duce this number to 3.6, so that one yard of DVDROTIC ne Fr hudentinne. G. such pipe would contain three gallons and sixtenths. ' If a three-inch pipe had been taken,

ödwp. Purger of water or phlegm. then 3 X 3 = 9; consequently there remains

He seems to have been the first who divided purges

into hydroticks and purgers of bile. Arbuthnot. but one figure to cut off. The gallons' place must therefore be supplied by a cypher, thus,

HYDRUNTUM, in ancient geography, a 0.9, and the yard of such pipe would contain noble and commodious port of Calabria, from but pine-tenths of a gallon.

which there was a short passage to Apollonia. For greater certainty, however, the following (Pliny) famous for its antiquity, and for the table and rules are introduced. They are ex- fidelity and bravery of its inhabitants; now tracted from Brunton's Compendium of Mecha- called Otranto. Long. 19° 15' E, lat. 40° 12' N. nics ; a recent little work, published at Glasgow, HYEMANTES, in the primitive church, and which is replete with useful information :

offenders who were not allowed to enter the

porch of the churches with other penitents, but Table of the Contents of a Pipe one inch dia were obliged to stand without, exposed to the meter for any required Height.

inclemency of the weather, even in winter.

HYEN, n. s. 2 Fr. hyene; Lat. hyæna. An Feet Quantity Weight in Gallons, | Hye'na, n. s. Sanimal like a wolf; said fabuhigh. in Cub. În. Avoir. Oz. Wine Mea. lously to imitate human voices.

I will weep when you are disposed to be merry; I 9:42 5.46 0.0407

will laugh like a hyen, when you are inclined to sleep. 18.85 10.92 0816

Shakspeure. 28.27 16:38 •1224

Out, out, hyena ; these are thy wonted arts, 37.70 21.85 •1632

And arts of every woman false like thee. 47.12 27.31 •2040

Milton. Samson Agonistes.

The hyena was indeed well joined with the beaver, 56:55 32 77

as having also a bag in those parts, if thereby we .2423

understand the hyena odorata, or civet cat. 65.97

.2448 38.23

Browne's Vulgar Ertours. 75.40 43.69 •3264

Oh the bewitcbing tongues of faithless men ! 84.82 49:16 .3671

'Tis thus the false hyena makes her moan 94.25 54.62 •4080

To draw the pitying traveller to her den. Otway.

A wonder more amazing would we find; 188.49 109.24 8160

The hyena shews it of a double kind; 282.74 163.86 1.2240

Varying the sexes in alternate years, 40 376.99 218.47 1.6300

In one begets, and in another bears. 50 471.241 273.09 2.0400

Dryden's Fables. 60 565.49 327.71 2.4480

The keen hyenu, fellest of the fell. Thomson.

Tearing, and grinning, bowling, screeching, swear659.73 382.33 2.8560

ing,

And with hyena laughter, died despairing. 80 753.98 436.95 3.2640

Byron. Don Juan. 90 848.23 491.57 3.6700

HYGEIA, or HYGIÆA, Greek, 'Yylela, in 100 942:48 546.19 4.0800

mythology, the daughter of Esculapius, and 200 1884.96 1092.38 | 8:1600

the goddess of health, among the ancient Greeks,

called by the Romans Salus. See Salus. Although the above table only gives the contents HYGINUS (Caius Julius), a grammarian, the of a pipe one inch in diarreter, it will serve as a freedman of Augustus, and the friend of Ovid,

covo era co

70

was born in Spain, or, according to others, in the horizontal board or table on which is de Alexandria. He wrote many works, all of which scribed the circular scale D E. (pou an inare lost, except his fabularum Liber, and Astro- crease or decrease of the humidity of the air, the nomicon Poeticon, lib. iv., and even these are index will show the quantity by twisting, and come down to us very imperfect. The best edi- consequently the increast' or decrease of moistion is that of Munker, in the Mythographi ture or dryness. Those Dutch toys calleci wede Latini; 2 vols. 810. 1081.

ther-h10115t's, where a small image of a man, and HYGROMETER, 1. S. Fr. hygrometre; one of a woman, are fixed upon the ends of an Gr. vypog and uitoew. An instrument to mea- index, are constructed upon this principle. For sure the degrees of moisture.

the index, being sustained by a cord or twisted A sponge, perhaps, might be a better hygrometer catsut, turns backwards and forwards, bringing than the earth of the river. Arbuthnul on Air. out the man in wet weather, and the woman in

The I1YGROMETER, HYGROSCOPI, or Novo- dry. 4. Fasten one end of a cord or catgut AB, NETET, is used for measuring the degrees of fig. 2, to a hook at A ; and to the other end a dryness and mcisture of the atmosphere, as the ball D of about 1 lb, weight; upon which draw barometer and thermometer measure its different two concentric circles, and divide them into any degrees of gravity and warmthi, although this number of equal paits, for a scale; then fit a instrument is far from being yet so perfect is style or index EC into a proper support at E, these. There are three general principles on so as the extremity C may almost touch the diwhich hygrometers have been construcied: 1. visions of the ball. There the cord twisting or The lengthening and shortening, or twisting and untwisting will indicate the change of moisture, untwisting, of string's by dryness and monsture; by the successive application of the divisions of 2. The swelling and shrinkin's of solid sub- the circular scale, as the ball turns round to the stances by moisture or dryness; and, 3, By the index C. An huurometr may be made of the increase or decrease of the weight of particular thin boards of ash or tir, by their swelling or bodies, which absorb the humidity of the auno- contracting. But these, and all the other kinds sphere.

of this instrument above described, become in There are various kinds of hygrometers; for time sensibly less and less accurate; till, at last, whatever body either swells by moisture, or they lose their eliect entirely, and suffer no altershriuhis by dryness, is capable of being formed ation from the weather. But the following sort into a by:rometer. Such are woods of most is much more durable, serving for many years kinds, particularly deal, ili, poplar, &c. Such with tolerable accuracy. To the extremity of also is catgut, the heard of a wild oat, and the balance, fig. 3, fix at E a sponge, or other twisted corid, &c. The best and most usual con- body, that easily imbibes moisture. To prepare trivances for this purpose are as follows: 1. the sponge, it may be proper tirst to wash it in Stretch a common cord or a fiddle-string along water very clean ; and, when dry again, in water a wall, passing it over a pulley; tixing it at one or vinegar in which there has been dissolved sal end, aud to the other end hanging a weight, ammoniac, or salt of tartar; after which let it carrying a style or index. Against the same wall dry again. Now, if the air become moist, the fit a plate of metal, graduated, or divided into sponge will imbibe it and grow heavier, and conany mumber of equal parts; and the hygrometer sequently will preponderate, and turn the index is complete. For it is constantly observed, that towards ('; on the contrary, when the air bemoisture sensibly shortens cords and strings; comes crier, the sponge becomes lighter, and the and that, as the moisture evaporates, they return index turns towards A ; thus showing the state to their former length again. The same is ob- of the air. Mr. Gould, in the Philosophical served of a fiddle-siring; and hence suclı strings Transactions, instead of a sponce, recommends are apt to break in damp weather, when not oil of vitriol, wbich grows sensibly lighter or slackened by the screws of the violin. Illence it beavier from the degrees of moisture in the air ; follows, that the weight will ascend when the so that, being saturated in the moistest weather, air is more moist, and descend again when it it afterwards retuins or loses its acquired weight, becomes drier; by which means the index will as the ar proves more or less moist. The alterbe carried up and down, and, by pointing to ation in this liquor is so great, that in tilly-seven the several divisions on the scale, will show the dars it has been hnown to chance its weight degrees of moisture or dryness. 2. For a more from three drachms to nine; and has shifted the accurate hygrometer, strain a whipcord or cat- tongue or index of a balance thirty degrees. So gut over several pulleys and proceed as before that in this way a pair of scales may afford a for the rest of the construction. Nor does it very nice hyrrometer. Oil of sulphur or cammatter whether the several parts of the cord be panum, or oil of tartar per deliquium, or the parallel to the horizon, or perpendicular to it, or liquor of fixed nitre', may be used instead of the in any other position; the advantage of this oil of vitriol. This balance may be contrivial over the former method being merely the baving in two ways; by either having the pin in the a greater length of cord in the same compass; middle of the beam, with a slender tonuue a foot for the longer the cord, the greater is the con- and a half long, pointing to the divisions on an traction and dilatation, and consequently the arched plate, as in tis. 3; or the scale with the degrees of variation of the index over the scale, liquor may be hung to the point of the beam for any given change of moisture in the air. near the pin, and the other extremity made so 3. Fasten a twisted cord or harpstring to a hook long as io describe a large arch on a board at A, piate HYGROMETER, fig. 1, and suspend by it placed for that purpose, as in fig. 4. It may be a weight B carrying an index C nearly touching observed, with regard to hygrometers of wood,

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