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BURN, in a Medicinal Senfe, a Solution of the Conti- nuity of a Part of the Body, by the Impreffion of Fire : or a Mark remaining on the Thing hurat. OiBurns, Phyfi- cians make feveral Degrees : The firft, when there are on- ly a few Puftules rais'd on the Skin, with a Rednefs, and a Separation of the Epiderma ftoni the genuine Skin. The fecond when the Skin is burnt, dried, and fhrunk, but without any Cruft or Scab. The third is, when the Flefh, Veins, Nerves, lie. are fhrunk, and form a Scab. Lufittt- nus recommends an Unguent, made of the Aih.es of Law- rel Leaves burnt, with Hog's Fat dropp'd on 'em, for a Bum j or, on occafion, the Unguent 'Populeum, with Vine Leaves' laid over it. Panarole obferves, that Clay laid on a Bum abates the Pain ; and the Brewers in Hol- land, ufe a Decoction of Ivy for the Cure of Suras.
Bums, however, are not only Difeafes, but in fome Cafes Remedies. M. Homberg obferves, that in the Die of Java, the Natives cure themfelves of a Cholick, other- wife Mortal, by burning the Soles of their Feet ; and cure themfelves of a 'Panaris, by dipping their Finger in boiling Waterfeveral times. Travellers relate many other Cafes of other Difeafes cur'd by burning : And we fee the Effects of itourfelves, in Horfes, Hounds, Birds of Prey, &c. A kind of Mols, brought from the Indies, has been likewife us'd for the Gout ; apply 'd, by burning if on the Part af- fected : and M. Homberg gives us Inftances of two Wo- men cur'd, the one of a violent Difeafe in the Head and Eyes, and the other of a Difeafe in the Legs and Thighs, by the accidental burning of thofe Parts. He adds, that hunting may cure in three manners ; either by putting the peccant Humors into a greater Motion, and making 'em take new Routs ; or by ditfolving and breaking their Vif- cidity, or by deftroying the Canals which brought them in too great Quantities. See Caustic, and Cautery.
BURNING, the Action of Fire on fome 'Pabulum or Fuel, whereby the minute Parts thereof are torn from each other, put into a violent Motion 5 and, affuming the Nature of Fire themfelves, fly off in Orhem. See Fire.
Burning, or Brenning, in our antient Cuftoms, was an infectious Difeafe, got in the Stews, by converting with leud Women ; fuppos'd to be the fame that we now call the Venereal {Difeafe : Whence that Difeafe is argu'd to be much more antient than the common Epocha of the Siege of Naples-. See Venereal Disease, and Clap.
The chief Objection againft Burning being the fame with the Venereal Difeafe, is, that the Remedies prefcrib'd againft the former, would be ineffectual in the latter : But, belide that it is not to be expected, the Meafures of the antient Phyficians fhould be calculated for the removing of any Malignity in the Mafs of Blood or other Juices, as in the Modern Practice ; inafmuch as they look'd on the Dif- eafe as merely local, and the whole of the Cure to depend on the Removal of the Symptoms : Befides this, it is matter of frequent Obfervation, that fome Difeafes grow more violenr, and others more remifs in courfe of Time : So that the Remedies which might have avail'd for the an- tient Brenning, may now fail as to the modern 'Pox.
The Procefs for the Cure, as deliver 'd by J. Arden, Chi-
rurgeon to K. Henry IV. is thus Contra Incendium Vir-
g t e Virilis interim ex Galore £5? excoriatione fiat talis fyrin- ga (i. e, inject io) lenitiva. Accipe lac Mulieris mafculum nutrientis g? parum aacarium, Oleum Violte ££? Ptifann : quibus commixtis per Syringam infundatur.
In an antient MS. written about the Tear 1500, is a Receipt for Brenning of the Pyntyl yat Men clepe the A- pegalle ; Galle being an old Word for a running Sore. And in another MS. written 50 Years after, is a Receipt for Burning in that Tart by a Woman. Simon Fifb, a zealous Promoter of the Reformation, in his Supplication of Beg- gars, prefented to K. Henry VIII. 1590, (peaking of the Ro?nifbfnnHs, fays, they catch the Pocks of one Woman, and bare 'em to another ; they be burnt with one Woman, and bare it to another : They catch the Lepry of one Wo- man, and hare it to another. And Boord, a Prieft and Phyftcian in the fame Reign, begins one of his Chapters of his Breviary of Health, thus : l"he 19th Chapter doth Jheia of the burning of an Harlotte. The fame Author adds, that if a Man be burnt with an Harlot, and domed- die with another Woman within a Day, he fhall burn the Woman he fhal! meddle withal: And as an immediate Remedy againft the Burning, he recommends the wafhing the 'Pudenda two or three times with Whitewine, or £lfc with Sack and Water.— In another MS. of the Vocation of John Bale to the Bifhoprick of OJfory, written by him- felf, he fpeaks of Dr. Hugh Weflon (who was Dean of Windfir in 1551?, but deprived by Cardinal Vole for Adul- tery) thus : " At this Day is leacherous Weflon, who is
- ' more practls'd in the Art of Breech-burning than all the
" Whores of the Stews. He not long ago brent a Beg-
4t gar of St. BotolphV Parifb. " See Stews.
Burning-Glass, or Burning Mirror, a Machine, whereby the Sun's Rays are collected into a Point ; and
by that means their Force and Effect extremely heighten'd, fo as to burn Objects placed therein. Burning Glaffes are of two Kinds , the firft Convex, which tranfmit the Rays of Light, and in their Paffage refract or incline them to- wards its Axis ; having the Property of Lens's, and actini according to the Laws of Refraction : See Lens, and Re" fraction. The fecond, which is the more ufual, are Concave ; very improperly call'd Burning Glaffes, beino ufually made of Metal : Thefe reflect the Rays of Ligh^ and in that Reflexion, incline them to a Point in their Axes ; having the Properties of Mirrors, and acting accor- ding to the Laws of Reflexion : which lee under Mirror. and Reflection.
The firft, or Convex kind, Authors fuppofe to have been unknown to the Antients ; but the latter are generally al- low'd. Hiftorians tell us, that Archimedes, by means hereof, burnt a whole Fleet. Now tho the Effect related be very improbable, yer does it fuffkiently prove fuch things were then known. The Machines here us'd, no body doubts, were Metallick and Concave ; and had their Focus by Reflexion : It being agreed, that the Antients were unacquainted with the Refracted Foci of Convex Glaffes. Yet, M. de la Hire has difcover'd even thofe, in the Clouds of Ariftophanes ; where Strepfiades tells Socra- tes, of an Expedient he had to pay his Debts, by means of a round tranfparent Stone or Glafs, us'd in lighting of Fires ; by which he intended to melt the Obligation : which in thofe Days was written on Wax. The Glafs here us'd to light the Fire, and melt the Wax, M. de la Hire ob- ferves, could not be Concave 5 fince a reflected Focus coming from below upwards, would have been exceedingly im- proper for that Purpofe : And the old Scholiaft of Arifto- phanes, confirms the Sentiment. 'Pliny makes mention of Globes of Glafs and Cryftal, which being expos 'd to the Sun, burnt the Clothes and Flefh on Peoples Backs ; and La&antius adds, that a giafs Sphere, full of Water, and held in rhe Sun, lighted the Fire even in the coldeft Wea- ther : which inconteitably proves the Effects of Convex Glaffes. Indeed, there is fome Difficulty in conceiving how they mould know they burnt, without knowing they magniffd; which 'tis granted they did not, till towards the Clofe of the Xlllth Century, when Spectacles and Te- lefcopes were firft thought on. For as to thofe Paffages in 'Plautus which feem to intimate the Knowledge of Spec- tacles, M. de la Hire obferves, they don't prove any fuch thing : And he folves this, by obferving, that their Burning Glaffes being Spheres, either folid, or full of Water, their Foci would be one fourth of their Diameter diftant from 'em : If then their Diameter were fuppos'd half a Foot, which is the moft we can allow, an Object muft be at an Inch and a half's Diflance to perceive it magnify'd : Thofe at greater Diftances do not appear greater, but only more confus'd, thro the Glafs than out of it. 'Tis no won- der, therefore, the magnifying Property of Convex Glaffes was unknown, and their burning one known : 'Tis more wonderful there fhould be 300 Years between the Inventi- on of Spectacles and Telefcopes.
Every Concave Mirror, or Speculum, collects the Rays difpets'd thro its whole Concavity, after Reflexion, into a Point or Focus, and is therefore a hitrning Mirror.
Hence, as the Focus is there where the Rays are the moft clofely contracted, if it be a Segment of a large Sphere, its Breadth muft not fubtend an Arch above 18 Degrees 5 if it be a Segment of a fmaller Sphere, its Breadth may be 30 Degrees. Indeed, Kircher obferves, that of all Burning Mirrors, thofe are the beft, whofe Breadth does not fubtend an Arch of 18 Degrees; fo that Experience and Demonftration go together.
As the Surface of a Mirror, which is a Segment of a larger, receives more Rays than another of a lefs, if the Latitude of each fubtend an Arch of 18 Degrees ; or even more, or lefs, provided it be equal : the Effefls of the greater Mirror will be greater than thofe of the lefs.
And, as the Focus is contain'd between the fourth and fifth Part of the Diameter, Mirrors that are Segments of greater Spheres, burn at a greater Diflance than thofe which are Segments of a fmaller.
Since, laftly, the Burning depends on the Union of the Rays, and the Union of the Rays on the Concave Spheri- cal Figure ; 'tis no wonder, that even wooden Mirrors gilr or thofe prepared of Alabafter, (gc. cover'd with Gold ; nay, even that thofe made of Paper, and cover'd with Straw, fhould be found to burn.
Among the Antients, the Burning Mirrors of Archi- medes and 'Proculus are eminent ; by one of which, the Roman Ships befieging Syracufe, under the Command of Marcellus, according to the Relations of Zonaras Tzetzes, Galen, &c. and by the other, the Navy of Vitellian befieging Byzantium, according to Tzetzes, were burnt. A- mong the Moderns, the moft remarkable Burning Mirrors, are thofe of Settala, of 'Villette, and tfchirnhaus. Settala, Canon of 'Padua, made a Parabolical Mirror, which ac- 3 cording
