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what flexible and elastic towards the heels, placed posterior to the cofan-bone, and in it assists in the action of those curious springs contact with movable, elastic, and not fixed we have just described.

or resisting substances, a very considerable The bars form two ridges, one on each lever is formed, and whenever the horny side the frog, extending from the heel of the frog comes in contact with the ground, it crust towards the toe of the frog. They first ascends, and then descends. The presappear to be a continuation of the crust, sure of the ground also expands the horny being, like it, composed of strong, longitu- frog, and the sensible frog expands the cardinal fibres. At the part where it joins the tilages, and at the heels and qnarters, imcrust, a very firm bearing is afforded for the mediately below the hair, totally goverus beel of the shoe. The use of the bars is to the direction of the future growth of the oppose any disposition there may be in the crust. hoof to contract, by acting as props to the This ascent of the frog not only, by its heels: but, in the common practice of wedge-like form, preserves the heels and sboeing, they are generally destroyed, for quarters from contraction, but affords to the farriers have supposed that they bind the horse an elastic spring, and prevents the heels together, and prevent their expansion- animal from slipping whenever it embraces they have therefore named them binders, and the ground. Without any anatomical in. cat them away, in order to open the heels, as quiry into its internal structure and union they term it.

with other parts, the shape and convexity The internal foot is endned with great sen- of the horny frog clearly demonstrate that sibility; and so nicely adapted to the coffin, it was formed to come into contact with the or hoof, that it completely fills it, without ground; and the more I investigate this subsuffering the least inconvenience from pres. ject, the more I am convinced that the use of sure; but when the foot has been improperly the frog is to prevent the horse from slipping, treated, when the frog has been mutilated, to preserve the cartilages and hoof expanded, the bars destroyed, and shoes applied that and, by its motion, to act as an elastic spring are either turned up or made very thick at the to the animal. heels, the hoof must necessarily contract, and Mr. Coleman contends, that Mr. St. Bel, its cavity become diminished; so that the nerves and many others, who suppose that the use and blood vessels being compressed, the circu- of the frog is merely to serve as a cushion, lation of the blood is impeded, and lameness or guard, to the tendon of the flexor muscle will naturally follow,

of the foot, and who, on that account, were All the anterior and lateral surfaces of the disposed rather to raise the frog from the sensible foot are covered with that mem- ground by a thick-heeled shoë, have been in branous or laminated substance which we an error. On the contrary, he maintains it to kave before described; but it differs from be a law of nature, that, unless the frog perthose laminae which are found on the in- form its functions, by being allowed to press ternal surface of the crust, in possessing nu- the ground, it must become diseased. Acmerous blood-vessels. At the upper part of cordingly, the practice of shoeing depends the sensible foot, where the laminæ terminate, very much on the functions of the frog being a roundish projecting body may be observed, understood. extending all round the coronet to the back If the opinions here advanced respectpart of the frog; this is termed the coronary ing its uses be well founded, then it must ring: its surface is covered with the extremi- follow, that paring the frog, and raising it ties of blood-vessels, and it is from this part from the ground, annihilates its functions, that the hoof is formed.

and ultimately, if not immediately, produces The natural frog of the borse, says disease; and that exposing the frog to presMr. Coleman, is placed in the centre of sure is the only proper method to keep it in the sole, externally convex, and of a wedge- health. Moreover, it has from experience like form, pointed towards the toe, but ex. been ascertained, that, unless the frog sustain panded as it advances to the heels. In the an uniform pressure when at rest, the heels as centre of the broad part there is a fissure, well as the frog contract, but if that organ or separation. The frog is connected in- be in close contact with the ground, then it ternally with another frog, of a similar figure, spreads and is free from thrushes and canker, bat different in structure. The external frog and operates as a wedge to keep open the hee's is composed of soft elastic horn, and totally of the hoof. insensible. The internal frog has sensation, Granite and other hard substances give and is much more elastic than the horny no pain to a frog exposed to constant presfrog; and at the extremity of the heels is sure in the stable ; but, when above the connected with two elastic substances called pavement, it generally becomes contracted, cartilages. The toe of the sensible frog is and the sensible frog inflamed, and then one united to the coffin-bone;. but more than stroke froin a projecting stone will produce nine-tenths of both frogs are behind the pain, perhaps lameness, while perpetual percothin-bone. The toe of the sensible and pendicular pressure is attended with salutary horny frogs, from their connection with effects. the coffin-bune, are fixed points, and have When the hoof contracts, the fre must no motion; but the heels of the frogs being also become contracted, and intlammation

For very

2

and a suppuration follows, called a thrush. the pavement, whatever shoes are employed,
No contraction, however, takes place where the hoof in the stable will be as much dis-
the frog is made to receive constant prese posed to contract as if the frog was raised
sure, as the standing perpetually on that any greater distance. I wish this fact to be
wedge increases its growth, presses upward well considered; for it has been supposed
the sensible frog, and expands the cartilages that shoes with a flat seat, without pressure
of the hoof. And as the first shoot of the to the frog, will prevent contraction. But
crust at the coronet is very thin, the di. I am fully convinced, that neither thick nor
rection of its fibres will be altogether re- thin heeled shoes, where the frog is raised
gulated by the width of the cartilages above pressure, and exposed to the lieat of
immediately below the hair at the quarters the stable, can prevent contraction or its
and heels, and the cartilages will be always effects; and, where the frog receives that
more or less expanded, and the hoof more pressure, the hecis cannot contract even
or less circular, as the frog has more or less with the most common shoes.
pressure.

obvious mechanical reasons, a wedge in the
On that principle, continues Mr. Coleman, centre of the heels, aide by the pressure from
I long since recommended a shoe with thin below, nust be best calculated to preserve
heels as the best formed shoe to bring the frog them expanded, or, when the heels are con.
on the same level; and with great truth I tracted, to forie then open. The heat of
can assert, that, although in some instances, the stable in all cases tends to contraction of
from a sudden misapplication of the thin, the hoof; but, with common shoes, there is
heeled shoe to improper feet, I have seen no pressure on the wedge, or other cause to
the tendons affected, yet, from all the expe- counteract that tendency. The artificial
rience I have since had, and from what I have frog, which is intended to cover and give
scen or heard of the practice of others, I know any degree of pressure to the natural frog
of no instance where the frog, from constant only, is made of iron. In order to fit the
pressure, did not expand and receive great natural frog, it is requisite to ascertain its
benefit,

width, the length of the foot, and the disWhere the frog is in a morbid state, tance between the lower surface of the shoe and unnaturally deprived of a perpendicular and the frog. But if the artificial frog be pressure, it is seldom safe to lower the lieels too long, the toe, which is tiat and thin, at once, so as to make the froy on a level may be shortened ; and if the heels of the with the shoe; and, in many cases, it is not shoe are higher than the artificial frog, possible with any shoes, or even without nothing more is requisite than to introduce shoes, to give the frog pressure on smooth a quantity of tow between the natural and surfaces; much less is it practicable for the artificial frog, so as to raise it equal or frog to rest on the gronnd when shod with above the level of the shoe. I have ascercommon thick-heeled shoes. In the stable, tained by experience, that no inconvenience therefore, while at rest, the frog is ge- talies place by raising the artificial frog even nerally raised above the shoe; and as prese one quarter of an inch above the shoe; but, sure is essential to its health, particularly in ordinary cases, it should not project more when the hoof is exposed to lieat, it ap- than one-sixth of an inch above the surface peared to me of great importance, in all of the shoe. It may, however, be imagined, cases where the heels of the shoe and the that so much perpendicular pressure to the frog cannot with safety be made on the same frog would retard rather than increase its level, to apply an artificial frog (see Plate growth ; but the very reverse is the fact ; IX.), to fit and give any degree of pressure, for as the frog, when long elevated above in the stable, to the natural frog, with any the ground, is very generally contracted, shoes. While the horse is in motion, and this unnatural lateral pressure excites intlamthe loof exposed to unequal surfaces, the mation of the sensible frog, and deprives, artificial frog should be removed, as the in a great degree, the blood vessels of the natural frog, out of the stable, will receive power of secreting horn. When the horny frequent pressure with any shoes; but that frog is exposed to perpendicular pressure, it period is of short duration, when compared gives healili

, and not disease, to the sensible to the length of time the horse re. frog. The blood vessels secrete their due mains at rest, and the frog raised from the proportion of elastic horn, and then the ground.

cavity of the frog is preserved, expanded, Artificial pressure is most particularly and fully equal to contain the sensible frog, wanted when the beat of the stable operates without the smallest degree of lateral pres. powerfully to contract the hoof. In all cases, therefore, where the pavement of the stable It therefore follows, that perpendicular pres. does not touch the natural frog, an artificial sure increases the bulk of the frog; while its frog is necessary to resist contraction of the absence from the ground produces contraction, hoof, thrushes, and canker. Sand-cracks, and lessons its growth. also, very generally arise from a contracted The following in an explanation of Plate hoof, and may be prevented by the artificial Ixxix. in which Mr. Coleman's PATENT ARTI

FICUAL Fkog is represented, with other figures frog does not absolutely rest on that illustrate the subject.

sure.

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Fig. 1. exhibits a view of the natural hoof frost, a variety of frogs are made, to be of the horse, which is of a circular shape. adapted to particular feet and particular

waa The external surface of the sole, of shoes. In cases of thrushes and canker of a concave form,

the frog, where no remedies without pressure 6bb The inferior edge of the crust. are likely to be serviceable, an astringent

ce The junction of the bars with the thrush-powder may be applied between the crust.

natural and artificial frog. And in contracted dd The points of the bars.

hoofs (or what has improperly been termed ce The sole between the heels of the crust chest-foundered), where it may not be adand bars, the seat of corns.

visible to lower the heels equal with the If Two carities between the sides of the horny frog, the artificial frog is essentially bars and the sides of the crust.

necessary. But, indeed, in every horse & The toe of the frog.

where the shoe and frog on a smooth surface hh The heels of the frog.

are not on the same level, whatever shoes may ii The cleft between the heels of the frog, be used, the iron frog in the stable should be the seat of thrushes.

applied ; and, in order to fix it with facility, Fig. 2. A view of the hoof with contracted the spring should first be laced under the heels, occasioned by raising the frog above shoe, and brought backward to the heels of the the pressure of the pavement in the stable. hoof. a a a The sole.

The toe of the iron frog should then be 66 The original seat of the bars, but im- inserted under the centre of the spring, and properly removed by the farrier.

pushed as far as the toe of the shoe, while the cc The original seat of the cavities be- other hand confines the spring until the centre tireen the bars and crust, but now, from con. of the spring meets the centre of the groove. traction, become solid horn,

The strap may then be buckled : and, to dis. dd The heels of the frog very much com- lodge the spring and iron frog, after the strap pressed by the contraction of the hoof.

is unbuckled, nothing more is requisite than a e e The width of the hoof at the heel, not small horse-picker introduced into a hole at being more than one half of the length from the bottom of the groove of the iron frog ; and s to g;

the spring being raised above the groove, and The extremity of the heels of the frog. carried gently forward, the frog nay be withi& The toe of the crust.

drawn from under the shoe without the smallest Fig. 3. The patent frog, made of cast and difficulty. wrought iron.

Mr. Coleman, in conclusion, wishes it to be a . The lower surface opposite the ground, clearly understood, that, in all cases where the formed of cast iron.

frog and the heels of the shoe are placed on 6 An irregular cavity for the reception of the same level, the patent frog is unnecesthe elastic spring, fig. 4.

sary. But where the frog is small, or the e The toe of the patent frog, formed of pastern joint long, or the action of the wrought iron, to be occasionally shortened and animal high, or the heels low, so as to renadapted to the length of the foot, and placed der the application of thin-heeled shoes imunder the toe of the shoe, to confine the arti- proper, or when the frog, from any cause, ficial frog from moving forwards.

is raised above the ground in the stable, an dd A hole in the heels of the iron frog for artificial frog is useful in all such cases, and the passage of a strap to buckle at the outside necessary to resist contraction of the hoof. quarter or coronet.

To this equally ingenions and candid stateFig. 4. A fiat steel spring to fix the artificial ment of Mr. Coleman, we are enabled to add frog in its place.

our individual testimony as to the soundness a An irregular projection, to be received of his reasoning, and the great practical into a corresponding concavity in the patent utility of his artificial frog, which is now frog.

very generally adopted in the stables of perb6 The ends of the spring, to be placed sons of fashion in the United Kingdom, and under the heels of the shoc opposite e e in may be had, at the small price of three shilfig. 1.

lings, at the Veterinary College, Little The toe of the artificial frog is intende Moorfields, as at a variety of other to be inserted under the toe of the shoe. forges. This effectually fixes the frog forwards; and Hoor, in geometry (or ungula), is a part to prevent backward or lateral motion, an cut off a cylinder cone, &c. by a plane passing irregular groove is made in the iron frog, to both through the base and part of the curve receive a corresponding piece of steel, placed surface. It has obtained its name from its under the heels of the shoe. In general, it resemblance to the hoof (ungula) of a horse. is necessary to fix the frog more firmly; and, For the contents and surfaces of such hoofs, for that purpose, a hole is necessary, made see Hutton's Mensuration, page 218–246, in the heel of the artificial frog, to receive 2d Edition. With respect

the sura strap, and to buckle at the outside quarter faces of conical ungulas formed by planes below the coronet. And that the artificial perpendicular to the base, Fatirer Guidofrog may, give pressure in all cases, with Grandi first remarked, that if a polygon be stues thickened, or turned up for hunting or inscribed in the base of a cone, and if on

to

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cach side of this polygon a plane be raised Yellinghy rivers. It is the port of Calcutta,
perpendicular to the base, the portion of and the only branch of the Ganges that is
the conical surface cut off towards the axis, commonly navigated by ships.
is equal to a rectilineal space. The portions HOOK. 8. (hoce, Saxon.) 1. Any thing
also of the cone cut off by the above planes, bent so as to catchi hold. 2. The curvated
towards the base, are in the same ratio with wire on which the bait is hung for fishes,
the segments of the base on which they and with which the fish is pierced. See Ang-
stand. In fact, whatever figure be inscribed LING. 3. A snare; a trap (Shakspeare).
in the base, if we conceive a right prismatic 4. An iron to seize the meat in the caldron
surface raised from the perimeter of the figure, (Spenser). 5. A sickle to reap corn (.Hor-
it will cut off from the conical surface a por- timer). 6. Any instrument to cut or lop with
tion which will be to it in the same ratio, (Pope). 7. The part of the binge fixed to the
namely, that of the radius of the base to the post. 8. Hook. (In husbandry.) A fielel sow:
slant height of the cone.

two years running (sinsvorth). 9. Hook or HOOFED. a. (from hoof.) Furnished with Crook. One way or other; by any expedient hoofs (Greeds).

(Iludibras). Hooked or Hoop-SHAPED. In botany, un- Hooks Or A Suip, those forked timbers gulate. Exemplified in the silicle of the which are placed directly under the keel. Rose of Jericho.

Hooks (Cax), those whieh being made last HooF-BOUND, in veterinary language, im- to the end of a rope with a noose (like thit plies a defect in a horse's hoof, in which it which brewers use to sling or carry their becomes so tight round the instep as to turn barrels on), are made use of for slings. the foot somewhat into the shape of a bell, Hooks (Foot), in a ship, the same with As the disease commonly proceeds from lard Futtocks. and undue exercise on rough road, the re- Hooks (Lcor), a tackle with two books; medy is best obtained by turning the animal one to hitch into a cringle of the main or to grass.

fore-sail, in the bolt-rope at the leech of the Hoof-Casting, in veterinary language, a sail by the clew; and the other is to hitch complete separation of a horse's hoof. This into a strap, which is spliced to the chessmay be produced by any cause exciting a tree. general inflammation and abscess in the HOOK-PINS, in architecture, are taper iron

ot. If the coffin-bone remain uninjured a pins, only with a hook-head, to pin the frame new hoof will commor.ly succeed: but the of a roof or floor together, old should never be taken away forcibly, Hooks (SHEER), in a ship, those looks like and a soft easy leathern boot or shoe should sickles fixed in the ends of the yard-arms, that afterward be applied, interlined with emol. if a ship under sail come to board her, those Jient ointment, and the dressing be renewed sheers may cut her shrowds, and so spoil her daily.

tackling. HOOGEVEEN (Henry), a learned Dutch- To HOOK. v. a. (from the noun.) 1. To man, born at Leyden, of poor parents, in catch with a hook (Addison). 2. To entrap; 1712. He received a good education, and

3. To draw as with a hook at the age of tifteen became a teacher himself (Shakspeare). 4. To fasten as with a look. for the purpose of supporting his parents. 5. To draw by force or artitice (Norris). In 1732, he was made under-master of the HOOKAH, among the Arabs and other academy at Gorcum, and shortly after he nations of the East, is a pipe of a singular was appointed to the care of the academy and complicated construction, throngh which at Woerden, from whence, in 1738, he re- tobacco is smoked. The Hindu's tobacco is moved to Culembourg. In 1715 he settled made up into a paste with spices : the to. at Breda, which he left in 1761 for Dort, but bacco being lighted, is put on the upper ex. after a residence of three years there he tremity of a tube, and the lower extremity went and settled at Delft, where he died in runs down into a shell or other vessel cori1794. His works are, I. An edition of Vigerus taining cold water, sometimes rose water; de Idiotismis Linguæ Græcæ ; 2. Doctrina through which the smoke is agreeably drawn particularum Lingua Gracæ, 2 vols. 4to. by means of another flexible tube, which is the 3. Some Latin poems and Discourses. A pipe, and about 12 feet long; posthumous piece of his, entituled, Dic- HOOKE (Robert), a celebrated inathemationarium Analogicum Græcuni,

is

tician, was born in the Isle of Wight, in printing.

1635; and having a taste for drawing, was TOOGLY, a small but ancient city of placed under Sir Peter Lely; but the oil. Hindustan, in Bengal. It is now nearly in colours disordering his head he soon quitted ruins, but possesses many vestiges of former painting, and was taken by Dr. Busby into greatness. In the beginning of the 18th cen. his house and under his tuition, There he tury it was the great mart of the export gained a good knowledge of the languages, trade from Bengal to Europe. Lat. 32. 30. N. and about 1653 went to Christ Church, Ox Lon, 88, 28 E.

ford, and became a member of the Philoso. Hoogưy River, an arm of the Ganges, phical Society then instituted in that univer: formed by the union of its two western sity. He assisted Dr. Willis in bis chymical branches, 'named the Cassium Buzar and operations, and afterwards became assistant

to ensnare.

now

to Mr. Boyle. He was one of the first fellows the ellipse, but the centre of gravity of the of the Royal Society, the repository of which earth and moon. He therefore made a covas entrusted to his care. In 1664 he was nical pendulum, whose tendency to a vertical made professor of mechanics to that learned position represented the gravitation to the body with a salary of 501. per annum, to sun, and which was projected at right angles which was afterwards added 301. more. At to the vertical plane ; and shewed, experithe same time he was elected professor of mentally, how the different proportions of geometry in Gresham College. After the fire the projectile and centripetal tendencies proof London he produced a plan of his own for duced various degrees of eccentricity in the rebuilding the city, which procured him the orbit. He then added another pendulum, appointment of one of the city surveyors, describing a cone round the first, while this though bis plan was not carried into effect. described a cone round the vertical line, in In 1668 he had a dispute with Hevelius re- order to see what point between them despecting telescopic sights, which he managed scribed the ellipse. The results of the expewith such warmth as to give great offence to riments were intricate and unsatisfactory; his scientific friends. In 1671 he attacked but the thought was ingenious. He candidly Sir Isaac Newton's Theory of Light and Co- acknowledged, that he had not discovered lours; and when that Philosopher's Principia the true law of gravitation which would procame out, Hooke pretended that the disco. duce the description of an ellipse round the very concerning the force and action of gra- focus, owing to his want of due mathematical vity was his own, which occasioned that knowledge ; and therefore left this investipatient man to feel some just resentment gation to his superiors. Sir Isaac Newton against bim. In 1691 archbishop Tillotson was the happy man who made the discovery, created bin M. D. by warrant. He died at after having entertained the same notions of his lodgings at Gresham College in 1702. He the forces which connected the bodies of the wrote a valuable work, entituled, Microgra- solar system, before he had any acquaintance phia, or Philosophical Descriptions of minute with Dr. Hooke, or knew of his speculations. Bodies made by magnifying Glasses, with 1660. The engine for cutting clock and observations and inquiries thereupon, folio, watch wheels.- The chief phenomena of 1665. Several of his papers are in the Philo- capillary attraction. The freezing of water a sophical Transactions, and after his death fixed temperature. appeared his posthumous works, in folio, 1705, 1663. The method of supplying air to a He was a man of great mechanical genius, diving bell. The number of vibrations made and the sciences are indebted to liim for by a musical chord, several valuable instruments and improve- 1661. His Micrographia was, by the counments. The following are the inventions and cil of the Royal Society, ordered to be discoveries to which he laid claim :

printed; but in that work are many just no. 1656. Barometer, a weather glass.

tions respecting respiration, the composition 1657. A scapement, for maintaining the of the atmosphere, and the nature of light, vibration of a pendulum.—And not long which were afterwards attributed as discoveafter, the regulating or balance-spring for ries to Mayow and others, who, though we watches.

are far from supposing that they stole their 1638. The double-barrelled air-pump.-

discoveries from Dr. Hooke, were certainly The conical pendulum.-His first employment anticipated by him. of the conical pendulam was

no less in 1666. A quadrant by reflection. genious and scientific than it was original.

1667. The marine barometer.—The gage He employed it to represent the mutual gravi- for sounding unfathomable depths. tation of the planets; a fact which he had 1668. The measurement of a degree of the most systematically announced. He had meridian, with a view to determine the figure shewn, that a force, perfectly analogous to of the earth, by means of a zenith sector. gravity on this earth, operated on the surface 1669. The fact of the conservatio virium of the moon and of Jupiter. Considering the vivarum, and that in all the productions and numerous round pits on the surface of the extinctions of motion, the accumulated moon, surrounded with a sort of wall, and forces were as the squares of the final or having a little eminence in the middle, as initial velocities. This doctrine he announces the production of volcanoes, he inferred that in all its generality and importance, deducthe ejected matter fell back again to the ing from it all the consequences which John moon, as such matter falls back again to the Bernoulli values himself so highly upon, earth. He saw Jupiter surrounded with an and which are the chief facts adduced by atmosphere, which accompanied him; and Leibnitz in support of his doctrine of the therefore pressed on him; as our air presses forces of bodies in motion. But Hooke was on the earth :-He inferred, that it was the perfectly aware of their entire correspon. same kind of power that maintained the sun dence with the Cartesian, or common docand other planets in a round form. He in- trine, and was one of the first in applying ferred a force to the sun from the circulation the celebrated 39th proposition of Newton's round him, and he called it a gravitation ; Principia to his former positions on this sube and said it was not the earth which described ject, as a mathematical demonstration of them.

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