AMPLITUDE. 



AMYGDAI.IX. 



in the public rtrceU of Borne till the time of Vespasian. The burden 

 of ship* WM reckoned by amphone. 



The amphora is still the Urgent liquid measure tued by the Veno- 

 tiuu. containing sixteen quart*. 



AMPLITUDE, the angular dwtanee of a celestial body from the 

 east point when it rues, or from the we*t point when it sets. It 

 drprad* upon the declination of the star and the latitude of the place, 

 and may be computed from the formula. 



tin. amplitude =: 



sin. declination 

 ooa, latitude. 



It must be meuurcd toward* the north or south point* of the 

 horiioa, according u the declination is north or south. For the fixed 

 tan, the amplitude remain* the same throughout the year : but for 

 the cun it varies with the declination, being nothing at the equinoxes, 

 and aliout 34 points of the compass at the solstices, or more exactly 

 89* 44' of amplitude, in the latitude of London ; that is, at the summer 

 solstice, it rues between N.E. by E. and N.E., and sets between N.W. 

 by W. and N.W. ; and at the winter solstice, it rises between S.E. by 

 E. and S.E., and seta between S.W. by W. and s.\V. 



The term amplitude was also applied to what is more commonly 

 called the range of a gun ; that is, the whole horizontal distance which 

 the gun will carry. It is sometimes also used in the integral calculus. 



AMPUTATION, from ampxtu, to cut off; the operation of cutting 

 off a limb from the body. Such is the constitution of the animal body 

 in general, and especially of the more perfectly organised body, that if 

 one part of it be diseased, the whole system suffers, while a general 

 disturbance of the system cannot exist long without producing specific 

 disease in some individual organ. Hence constitutional and local 

 diseases are found to exert a most important influence over each other. 

 Some local diseases are of an incurable nature, and proceed progres- 

 sively from bad to worse. At first, these diseases may not materially 

 affect the general health, but in their progress they produce go much 

 constitutional disturbance, UK to endanger life, and ultimately to 

 destroy it. In this case, life is really endangered and destroyed by the 

 local malady ; remove that, provided the removal can be effected before 

 the general health in irreparably impaired, and not only is death 

 averted, but health itself is restored. Hence, in all ages, the necessity 

 and advantage have been obvioiu enough, of removing a part of the 

 body for the sake of preserving the remainder, and men have always been 

 willing to submit to the loss of a limb in order to save the body, on 

 the ground " that it U better to live with three limbs than to die with 

 four." 



But although it must always have been clear, that it is a gain to 

 save life even at the cost of a limb, when nothing but the removal of 

 the limb can preserve the body, yet it was not always easy to make 

 the sacrifice. Whoever understands the circulation of the blood, and 

 considers the quantity that is sent, and that must necessarily be sent, 

 to each member of the body for its nourishment, and the magnitude 

 of the blood-vessels that are divided in cutting off a limb, will readily 

 perceive how impossible it must have been to perform the operation 

 of amputation before any certain mode was known of stopping the flow 

 of blood from the wounded blood-vessels. But no such mode of 

 stopping haemorrhage was known to the ancientn : consequently, 

 though they daily saw the necessity of performing the operation of 

 amputation, yet they looked upon the operation with terror, and 

 shrunk from the responsibility of undertaking it. And no wonder : 

 when they did venture upon it, the consequences were appalling. 

 They cut through the flesh with a red-hot knife, hoping by this means 

 to prevent a fatal loss of blood. After having performed this opera- 

 tion, they dressed the wound with scalding oil, in order to complete 

 what the burning knife may have left imperfect. But these expedients 

 stopped only for a short time the flow of blood. The whole surface of 

 the wound was converted into an eschar, which for a time stopped the 

 bleeding. But the eschar being dead matter it was at length thrown 

 off by the action of the living part* beneath. The moment this took 

 place, the mouths of the blood-vessels were again opened, haemorrhage 

 took place just as at first, and the patient perished from loss of blood. 

 The uniformity with which this event took place after amputation 

 performed in this mode, could not but cause the operation to be 

 regarded with dismay. Nevertheless, it is pretty clear, that in the 

 time of Celsus, the surgeons of that age were not without some notion 

 of the true mode of stopping haemorrhage from wounded blood-vessels, 

 for that writer gives particular directions to take hold of the vessels, 

 to tie them in two places, and then to divide the intermediate portion ; 

 certain, however, it is, that this practice was not extended to amputa- 

 tion, because nothing was ever amputated by the ancients but a part 

 absolutely mortified or dead ; and in a part thus mortified or dead, it 

 is not practicable to secure the blood-vessels by the needle and ligature. 

 The general introduction into surgery, of the method of (topping 

 hemorrhage by taking up the divided blood-vessel with a needle, and 

 placing a ligature around it, must, therefore, be considered as much a 

 modern improvement, as if no allusion whatever had been made to it 

 by ancient writers. 



But if a knowledge of the mode of stopping haemorrhage by tying 

 the blood-vessel, be indispensable to the safety of surgical operations 

 in general, the knowledge of some mode of preventing the loss of blood 



during the actual performance of an operation Is indispensable to the 

 safety of the operation of amputation in particular. So large are the 

 trunks of the main blood-Teasels that supply the limbs, and so great is 

 the quantity of blood that flows from them in a short space of time, 

 that lues of life is always the consequence of a want of command over 

 these great vessels. By the invention of the instrument termed the 

 tourniquet, an invention of the 17th century [ToriixiQUCT], this com- 

 mand is obtained. By these instruments, then, namely, tile tounti<|iirt , 

 and the needle and ligature, modern surgeons have, such a , 

 command over the blood-vessels, that operations may be performed, 

 in which the largest trunks are divided without the loss scarcely of .1 

 single drop of blood. On this account, the mere removal of a limb 

 excites in the modern surgeon no degree of anxiety ; the operation of 

 amputation is scarcely ever attended with the slightest hazard ; never- 

 theless, there are circumstances connected with amputation of the 

 greatest possible importance, delicacy, and difficulty, on a clear and 

 correct view of which life depends; to obtain such a view, the most 

 extensive knowledge, and the most accurate discrimination, are requi- 

 site; while, to act in conformity with it, a high degree of moral 

 courage in often no less necessary. Perhaps the determination of the 

 exact time at which to amputate is sometimes among the most difficult 

 points of surgery; that is, the determination of the time when the 

 preservation of the limb is no longer possible ; and when, therefore, it 

 is right to put an immediate stop to any further exhaustion of the 

 health and strength by the removal of the limb. The recent intro- 

 duction of the use of anaesthetics, in order to produce a state of insen- 

 sibility in those submitting to the operation of amputation, has been 

 found to exercise a most beneficial effect on recoveries after amputation. 

 ' ANESTHETICS.] 



AMULET, in barbarous Latin, A mulct am, or Amoletam. It cornea 

 from the Arabic Hamalet, a thing suspended. An amulet hung round 

 the neck, or carried in any other way about the person, U absurdly 

 believed to have the effect of warding off morbid infections and other 

 dangers, and even of curing diseases by which the body has been 

 already attacked. The belief in the efficacy of amulets has subsisted 

 at some time among almost every people, and the thing has been 

 denoted by a great variety of names, which it is unnecessary here 

 to enumerate. The phylacteries, or bits of parchment with passages 

 from the Bible written upon them, which the Jews were wont to carry 

 about with them, were amulets; such were probably the ear-rings 

 mentioned in Genesis xxiv. 4 ; and in Hosea it 13. Jerusalem i- 

 represented as decking herself with the ear-rings of Baalim. Of the 

 same character as the Jewwh phylacteries are the scraps of 

 inscribed with sentences from the Koran, which the Moorish priests 

 sell to the negroes of Africa, and to which the latter give the name 

 of Fetidia. This superstition, which existed alao among the Greeks 

 and Romans, appears to have in early times prevailed extensively 

 among the converts to Christianity, if we may judge by the denun- 

 ciations directed against it by St. Chrygostom, and others of the 

 fathers. But even down to our own day, it has continued to be an 

 article of the popular creed, that certain medical preparations, and 

 other things, merely carried about the person, have the power both of 

 repelling and of healing diseases. Even the celebrated Robert Boyle 

 adopts this notion, assuring us that he once experienced the efficacy 

 of such an amulet in his own case. " Having been one summer," he 

 says, "frequently subject to bleed at the nose, and reduced to employ 

 several remedies to check that distemper; that which I found the 

 most effectual to stanch the blood was some moss of a dead man's 

 skull (sent for a present out of Ireland, where it is far less rare than in 

 most other countries), though it did but touch my skin till the herb 

 was a little warmed by it." (' Essay of the Porousness of Animal 

 Bodies.' See also his 'Essays on the Usefulness of Natural Philo- 

 sophy,' and his ' Experimental Discourse on some Unheeded Causes of 

 the Insalubrity and Salubrity of the Air.') The anodyne necklace, 

 which consists of beads formed from the roots of white bryony, and is 

 sometimes hung around the necks of infants with the view of assisting 

 their teething, is an instance of the still surviving confidence in the 

 medical virtue of amulets. Such also is the belief generally enter- 

 tained by seafaring people, that a child's caul on board their lii|> will 

 preserve them from being lost and many other examples might lie- 

 easily quoted. Even in 1858, though probably without inueh KUIMT- 

 stitious belief, rliarna were advertised set as jewels, and amon^ tin-in 

 were pieces of the Atlantic cable. 



AMYGDALIC ACID. (C W H M 0,,). Produced by the action of alkali. * 

 upon amygdalin. 



C.,H,,NO S1 + JHO = C,n,.0,, + MI,. 



Amrpdalin. 



Amygdnlic acid. 



Evaporated on the water-bath, solution of amygdalic acid dries up to a 

 gummy moss, which is highly deliquescent, insoluble in ether, and in 

 boiling absolute alcohol. By the aid of heat it reduces the salt* of 

 silver. Its salts are generally gummy and uncrystollisable. Like amyg- 

 dalic acid itself, they yield formic acid, carbonic acid, and hydride of 

 benzoyl, when boiled with a mixture of peroxide of manganese and 

 sulphuric acid. 



AMYGDALIN. (C M H..NO n -f6aq.) A crystalline substance first 

 obtained by Robiquct, and Boutron Charlard, and afterwards studied by 



