VOL. XX.] PHILOSOPHICAL TRANSACTIONS. 279 



the sea, by a mouth 84 leagues broad, and is so deep, that a ship of the largest 

 size may go up almost to its source. 



2. Trailc du Cancer, ou Von expJique sa Nature, et ou fon propose les Moyens 

 les plus surs pour le guerir methodiquement. Avec un Examen du Sysleme et 

 de la Pratique de Mr. Helvetius. Par. Mr. J. B. Alliot, Conseillier du Roi, 

 Medecin Ordinaire de sa Majeste, et de la Bastille. Paris. 1698, Svo. 

 N° 240, p. 199. 



This author thinks that cancers come from acidity and are to be cured by 

 alkalies and absorbing medicines. He recommends for their cure, a preparation 

 of red arsenic which is put into a very strong lixivium, the solution is poured off 

 by inclination, it is filtrated, and to this liquor is put vinegar of lead, till no- 

 thing precipitates. This powder precipitated is sweetened by 12 or 15 times 

 pouring warm water on it. The last water ought to come off insipid ; then burn 

 either pure spirit of wine, 5 or 6 times on it, or such to which is put a tinc- 

 ture of opium ; then powder it, and it is ready for [external] use. 



Concerning a Roman Shield. By Mr. Ralph Thoresby, F. R. S. 



N° 241, p. 205. 



Having procured an old Roman shield, of a different form from that I had 

 before, and observing them both to be of different materials from the usual de- 

 scriptions of them, I resolved to make a more particular inspection into their 

 texture, and whereas they are generally said to be e ligno corio superinducto, 

 upon a strict survey, there is nothing of wood, but the handle, in either of 

 them. The ancient Romans had three words, scutum, parma, et clypeus, for 

 that defensive weapon we generally English by a shield, which notwithstanding 

 their different forms or matter, their authors frequently confound, as probably 

 we now do shield, buckler, and target. This shield or buckler is of the parma 

 kind, and rightly so called, being quite round ; whereas the scutum was mostly 

 oval. It is 15 inches diameter, of which a little more than a third part is taken 

 up with the umbo, or protuberant boss at the centre, which is made of an iron 

 convex plate, wrought hollow on the inside, to receive the gladiator's hand ; 

 on the centre of this is a smaller boss, in which there seems to have been fixed 

 some kind of cuspis, or sharp offensive weapon, to be used when they came to 

 fight hand to hand. From the umbo, the shield is 4 inches and a half broad 

 on eacli side, in which are 1 1 circular equidistant rows of brass studs of that 

 size, that 222 are set in the outmost circle, which is 45 inches, that being the 

 circumference of the buckler and so proportionably in the lesser circles to the 



