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THE

BRITISH ENCYCLOPEDIA.

SURGERY.

PARTICULAR DISLOCATIONS.

elevated, without extreme pain, to a line

with the acromion. Great pain is caused Lower jaw. This bone can only be lux. by the pressure of the head of the bone ated forwards, when the condyloid pro- in its unnatural position, particularly cesses advance beyond the eminentiæ arti. when it lies in the axilla. Our object is, culares. In this case the mouth remains to dislodge the head of the os brachii open, and cannot be shut; there is pain; from its unnatural situation, in order to impaired and almost destroyed articula- bring it on a level with the glenoid cavity tion and deglutition, &c. One or both of the scapula. To accomplish this purcondyles may be displaced. To reduce it, pose, extension must be made; that is, the the thumbs, well covered, should be intro- limb must be drawn forcibly outwards; duced as far backward as possible along and the bone itself should be made to the grinding teeth. The surgeon then operate as a lever, which can be best efelevates the front of the bone with his fected by the surgeon's knee placed un. fingers and the palms of his hands, while der it towards the head, while he depreshe depresses the condyles with his ses the elbow at the proper time, so as to thumbs; and the latter prominences are raise the head towards the glenoid cavity. thus forced back into the glenoid cavities The patient's body should be fixed, by of the temporal bones.

placing a broad towel round the chest, Dislocations of the head and vertebræ and tying it to some immoveable point. are probably imaginary occurrences, as The extension should be gradual, and we know hitherto of no well attested ex.' kept up unremittingly, which can be ample of their occurrence.

best effected by means of pullies. The The os humeri is probably luxated more elbow should be bent, and the extending frequently than any other bone. It may power applied just above the condyles of be displaced downwards, forwards, and the humerus. When the surgeon finds backwards. In all these cases a vacancy that the head of the bone is drawn out of is distinguishable under the acromion, in its unnatural position, he may allow the consequence of the absence of the head extention to be remitted, and depress the of the humerous from the glenoid cavity elbow. The arm should afterwards be of the scapula. The head of the bone kept quietly in a sling, a piece of soap forms a preternatural tumour in some plaster, and a spica bandage, being applisituations. The elbow cannot be carried ed to the shoulder. close to the chest, nor can the limb be Elbor. Dislocations at this joint are very difficult to discover, from the swell. The ankle may be dislocated outwards, ing which comes on so quickly. The the fibulæ being at the same time broken. radius may be displaced forwards; and This is generally a compound luxation ; here the flexion of the elbow is almost the extremity of the tibia, when displaced entirely destroyed. The ulna may at the from the astragulus, very often penetratsame time be driven backwards: it maying the integuments. Formerly this acalso be pushed inwards, so as to occupy cident was considered as a cause of am. the place of the radius. All these are putation; and many practitioners have easily reduced, when they are ascertain. been in the habit of sawing off the proed. Leeches and cold washes should be jecting portion. Yet, by replacing the employed afterwards. line given, whose angles, at the base, ther seen, that every figure may, either shall be quintuple to that at the vertex; directly or circuitously, be commuted which may easily be done by the in- into a triangle, of corresponding area: tersection of a quadratrix, or any other but it may be necessary, at the same curve of the second kind.

bone, closing the wound, keeping the Wrist. The distortion consequent on parts quiet, &c. the injury has been a displacement of the carpus is so consi- often recovered. Luxation may also ocderable, that the nature of the case is ren- cur in the opposite direction, and fordered immediately obvious. The reduc. wards. The latter is very difficult to re. tion is easy ; and after it has been accom tain in place, as the muscles of the calf plished, the hand and fore-arm should be are so apt to move the foot. bound on a splint, and supported by a SURIANA, in botany, so named in ho. sling.

nour of Joseph Donat Surian, a genus of Thigh. The os femoris may be dis. the Decandria Pentagynia class and order. placed downwards and inwards, so that Natural order of Succulentæ. Rosaceæ, the head rests on the obturator foramen; Jussieu. Essential character: calyx five. upwards and outwards, when the head is leaved; petals five ; styles inserted into towards the sacro-ischiatic foramen, and the inner side of the germs: seeds five, the trochanter forwards, and upwards naked. There is but one species, viz. S. and forwards, so that the head rests upon maritima, a native of the sea coast of the os pubis. In the first case, the toes South America, and the islands of the are turned out, and the limb elongated, West Indies. In the second, the limb is shortened, the SURRENDER, in law, a deed or in. foot turned inwards, and the buttock strument, testifying that the particular temore prominent. Great pain is excited nant of lands or tenements for life, or by attempting to move the limb in all years, doth sufficiently consent and cases of luxation, and a vacuity is dis- agree, that he which has the next or imcernible in the natural situation of the mediate remainder, or reversion thereof, head of the bone. The patient should be shall also have the present estate of the placeri on the side opposite to the acci. same in possession, and that he yields and deni, and his pelvis should be fixed by gives up the same unto him ; for every means of a sheci passed under the perine. surrenderer ought forthwith to give pos. um. Extension may be made by fixing a session of the things surrendered. Where broad towel, or the pullies, just above a surrender is made in consequence of a the condyles. When the head of the fresh lease, and that lease turns out invabone is on the dorsum ilii, the extension lid, the surrender is considered as not is to be continued until it has been valid, and the former lease is establishbrought to the acetabulum, into which ed. Surrender into the hands of the the surgeon must guide it. In the dislo. lord is the mode of passing copyholds, eation of the obturator foramen, we and a surrender to the use of a will is should make a lever of the bone, by pass. necessary, in order to pass them by a ing a towel under the thigh, near the tro. will. chanter, and elevating it, after a slight SURROGATE, one who is substitut. extension has been made, the condyles ed or appointed in the room of anobeing at the same time depressed. ther; as the bishop or chancellor's sup

The patella may be dislocated either in- rogate. wards or outwards. Its reduction is very SURSOLID, in arithmetic and algebra, easy, when the muscles inserted into it the fifth power, or fourth multiplication have been relaxed.

of any number or quantity, considered as The knee hardly admits of complete a root. See Root. luxation, without such injury of the parts SURSOLID problem, in mathematics, is as would rensler the loss of the limb nes that which cannot be resolved but by cessary. The nature of the accident curves of a bigher nature than a conic must be obvious from the altered figure section, v. gr. in order to describe a reof the parts, and replacement is perfectly gular endecagon, or figure of eleven easy. Infainmation must be guarded sides in a circle, it is required to de. against afterwards.

scribe an isosceles triangle on a right

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time, to observe, that the squaring of SURVEYING. This important art, the circle has not hitherto been perhowever difficult its attainment may ap. fected; though we have arrived so nearpear, is nevertheless to be comprised ly to the completion of that object, as to within a very few general rules. The ac. leave no room for regret at the want of curacy of the work must depend entirely absolute precision. on the correctness of the instruments em These points being completely under. ployed, the steadiness of the band and stood, the learner may proceed to the rueye of the operator, and the faithfully diments of surveying ; supposing him to tracing the given lines and angles on the be grounded in the few preliminary propaper designed to exhibit the estate, or blems which enable him to describe the premises under examination. The fol. ordinary figures : should he not have oblowing leading principles will give an in- tained any previous information on that sight into the mode of displaying the re. subject, we recommend that he turn back sults, whatever may be the means em to the heads of GEOMETRY and Marieployed for their computation. First. We MATICAL instruments : under which he are to reject the actual curvature of our will find various items indispensable toglobe, in all land surveys; that is, where wards his progress. no current of water, or the level of any We shall submit a few propositions, fluid is under consideration : such curva. which the student may work with his tare amounts to about eight inches in compasses, plain scale, and protractor: every mile, either of latitude or of longi. when able to do all that may be needful tude. In brief, we consider the earth to on paper, he may then try his hand with be flat, instead of spherical. Secondly, one or other of the various instruments in We must ever carry in mind, that every use among surveyors. triangle is equal to half a parallelogram Proposition 1.To ascertain the conof equal base and altitude; as shewn un- tents of the square field ABCD, fig. 1. der the head of GEOMETRY. Thirdly. Plate XV. Miscel.” Here little is to be That wherever there is a deviation from done ; one of these sides being measured, the horizontal, there will be a greater ex- say 70 yards, and multiplied by itself, tent of surface displayed on a site than will give 4,900 square yards for the area; if the same were horizontal. To illustrate or one acre (i. c. 4,800 square yards) and this, let an orange be cut through in the 100 square yards. middle, and the fat part, i. e. the section, Proposition II. To survey the field be placed on a level table : it is evident ABCD, fig. 2.This figure having the that the round surface of the half orange sides AB and CD parallel, and at right will offer more surface than the flat section angles to AD, add the lengths of those which lays upon the table: but, if it were parallels, say 70 and 90 yards, together ; required to build on the semi-spherical divide half their sum (i. e. 80) and multisurface, it would be found that no more ply that half by the depth of AD, say 70; houses, &c. could be raised thereon, than which being multiplied by the medium would stand on the extent of the fat sec. length, GF, gives an area of 5,000 square tion. The reason of which is, that no yards. The parallelogram, ABED, might more perpendiculars can be raised on have been computed by simply multiplyone than on the other. This shows how ing its length by its breadth ; and the fallacious is the mode of purchasing what triangle, BCE, might be taken separate. is called side-long, or hanging, land byly, thus: the depth, (or altitude) BE, 70 the acre. The greater the deviation from yards, to be multiplied by half CE, (i. e. the horizontal, the more is the base di. 10 yards) this would give 700 ; and the · minished. Fourthly. The surveyor must produce of AB, which is 70, by BE, which recollect, that all planes, of whatever ex. is also 70, would be 4,900: making in all tent or form, may be divided into, and be 5,600, as above shown. represented by, triangles of various forms Proposition III. “ To survey the inand dimensions, whose aggregate will clined parallelogram ABCD, fig. 3.” It amount to the measurement of the area is to be observed that, in all inclined fi. thus partitioned off: for, as Euclid justly gures, the altitude is ascertained by a perobserves, “ All the parts, taken together, pendicular from the base, as at C, to the are equal to the whole.” It will be fur- parallel of that base, as at E, on the line

VOL. XIL

B

AB. Now the triangle BEC being equal amount to the whole area of the penta. to the triangle DFA, and likewise simi. gon. lar thereto, it is evident that, by transpog. Proposition VII. « To ascertain the ing the former from the right to the left area of the irregular six-sided figure, or of the figure, it would make it rectangu hexagon, (fig. 7) ABCDEF.” In this lar, as shown by the dotted line : there. some of the angles point inward. First fore multiply the base DC, say 100 yards, draw the line CE, which will divide the by the altitude CE, say 80 yards, and the figure into two trapezia, viz. CEBA and area will be found to contain 8,000 square CEFD, next divide each of these trape. yards.

zia by the diagonals, BE and CD, into Proposition IV. “ To survey the irre. two triangles respectively: the areas of gulars, fig. 4." Here AC and BD are the four triangles, BAE, BCE, FCD, and parallel, but neither CD nor AB are per. CED, will, when added together, exhibit pendicular thereto, nor parallel between the contents of the whole figure. themselves. We must, therefore,cut off Proposition VIII. « To measure the the triangles AEB and CFD ; whose area irregular field ABCDE, fig. 8.” The will be found by multiplying half their figure here given has two curved sides, respective breadths by their whole one of which projects, the other of which depths: or their whole breadths by half infects: the ordinary parls which can be their depths: the centre part, ECBF, is divided into triangles are worked in the treated as a parallelogram, already de manner already shown ; but the curved scribed. The whole of the calculations parts must be measured in the following being added together give the area of the mode: Draw the line ED, and from it entire figure ACBD.

make three or more off-sets to the curyProposition V. “To ascertain the area ed part; take from E to 1, as a base, of the trapezium, ABCD." This figure and half the depth of the off-set 1, as an is no where parallel, and has all its sides altitude; multiply them together: then of unequal lengths. The easiest mode of take from 1 to 2, as a base, and the mean surveying it is, by drawing a diagonal be. of the depths of the off-sets 2 and 3, for tween the two most distant points, C and the altitude; multiply these also together: B; and making off-sets, rectangular to do the gaine for the space between 2 and that diagonal, from E to A, and from F to 3, and Chi sulate the end, between 3 and D. These off-sets give the altitudes; EA D, as wus d ne from E to 1; the sum of being the altitude of the triangle CAB, their gr veral products, added together, say 40 yards; and FD being the altitude will show the area of the curve. As of the triangle BDC, which we will take the other curve bends inward, draw the at 80 yards. Now the diagonal, CB, be- line AE, and treat it the same as was comes a base common to both triangles; done regarding ED: then considering therefore add the two altitudes together; the entire triangle, AED, as a part of the namely, 40 to 80, which makes 120; take field, compute its contents, and deduct their half = 60, and multiply by the base from it the measures taken, by means of which we will call 140 : the area will con. the off-sets 4, 5, 6: the residue added tain 8,400 square yards. It will be seen to the contents of the curve from E to D, that this proportion is, in a great mea and the triangles, ABC and ACD, will sure, the foundation of all horizontal com. show the area of the whole figure putation ; and the student should remark, ABCDE. It is obvious that, in this manthat all figures, having many sides, may ner, the extent of water may be deducted be divided into trapezia, and those again from the area of any field. into triangles: each figure will have two "The next figure, No. 10, shows the sides more than the numbers of triangles method of surveying with a plain-table, it contains: thus, fig. 5 has four sides, which usually stands upon three legs, and and contains two triangies; fig. 6. has has a compass attached to one side. five sides, and contains three triangles. There is a box-wood frame that fits on

Proposition VI. “To survey the pen. the board of the plain-table, and is gradutagon, or five-sided field, ABCDE, fig. ated with 360 degrees. This serves to 6." Divide it into the three triangles, show the direction of any line from the ABC, DAC, EAD, and having found centre of the board, where there is a their respective altitudes, as already brass stud, or plate, let in; and it also shown, by perpendiculars drawn to their compresses the paper so as to prevent its summits from their respective bases, shifting. To this instrument there is a multiply half those altitudes by those brass rule of two feet long, with ends bases, and the three products will turned up at right angles, in which are

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