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very fine, that two yards thereof shall 

 j only weigh one grain ; and consequently 

 j ninety -eight yards of the same wire only 

 forty -nine grains : so that a single grain 

 of gold here gilds ninety-eight yards ; 

 i and, of course, the ten-thousandth part 

 of a grain is here above one-third ot % an 

 inch long. And since the third part of 

 an inch is yet capable of being divided 

 into ten lesser parts visible to the naked 

 eye, it it evident that the hundred- 

 thousandth part of a grain of gold may be 

 seen without the assistance of a micro- 

 scope. Proceeding in his calculus, he 

 found, at length, that a cube of gold 

 whose side is the hundredth part of an 

 inch, contains 2, 433,000,000 visible parts; 

 and yet, though the gold wherewith 

 such wire is coated be stretched to such 

 a degree, so intimately does its parts co- 

 here, that there is not any appearance of 

 i the colour of the silver underneath. 



Mr. Boyle, examining some leaf-gold, 

 found that a grain and a quarter's weight 

 I took up an area of fifty square inches ; 

 supposing, therefore, the leaf divided by 

 parallel lines one -hundredth of an inch 

 apart, a grain of gold will be divided into 

 five hundred thousand minute ^squares, 

 all discernible by a good eye : and the 

 same author shews, that an ounce of gold 

 drawn out into wire, would reach 155 

 miles and a half. 



But M. Reaumur has carried the duc- 

 tility of gold to a still greater length: a 

 gold wire, every body knows, is only a 

 silver one gilt. This cylinder of silver, co- 

 vered with leaf-gold, they draw through 

 the hole of an iron, and the gilding still 

 keeps pace with the wire, stretch it to 

 what length they can. Now M. Reau- 

 mur shews that, in the common way of 

 drawing gold-wire, a cylinder of silver 

 twenty -two inches long and fifteen lines 

 in diameter is stretched to 1,163,520 

 feet, or is 634,692 lines longer than be- 

 fore, which amounts to about ninety- 

 seven leagues. To wind this thread on 

 silk for use they first flatten it, in doing 

 which it stretches at least one-seventh 

 farther: so that the twenty -two inches are 

 now 111 leagues: but in the flattening, 

 instead of one-seventh, they could stretch 

 it one-fourth, which would bring it to 120 

 leagues. This appears a prodigious ex- 

 tension, and yet it is nothing to what 

 this gentleman has proved gold to be ca- 

 pable of. 



DUCTILITY of glass. We all know, 

 that when well penetrated with the heat 

 ef the fire the workman can figure and 

 manage glass like soft wax ; but what is 



most femarkable, it may be drawn, or 

 spun out, into threads exceedingly long 

 and fine. Our ordinary spinners do not 

 form their threads of silk, flax, or the 

 like, with half the ease and expedition 

 as the glass-spinners do threads of this 

 brittle matter. We have some of them 

 used in plumes, for children's heads, and 

 divers other works, much finer than any 

 hair, and which bend and wave like 

 hair with every wind. Nothing is more 

 simple and easy than the method of 

 making them. There are two workmen 

 employed ; the first holds one end of a 

 piece of glass over the flame of a lamp, 

 and when the heat has softened it, a se- 

 cond operator applies a glass hook to 

 the metal thus in fusion ; and withdraw- 

 ing the hook again, it brings with it a 

 thread of glass, which still adheres to 

 the mass : then, fitting his hook on the 

 circumference of a wheel about two feet 

 and a half in diameter, he turns the 

 wheel as fast as lie pleases ; which, 

 drawing out the thread, winds it on its 

 run, till, after a certain number of revo- 

 lutions, it is covered with a skein of 

 glass thread. The mass in fusion over 

 the lamp diminishes insensibly, being 

 wound out like a clue of silk upon the 

 wheel ; and the parts, as they recede 

 from the flame, cooling, become more 

 coherent to those next to them, and this 

 by degrees : the parts nearest the fire 

 are always the least coherent, and, of 

 consequence, must give way to the ef- 

 fort the rest make to draw them towards 

 the wheel. The circumference of these 

 threads is usually a fiat oval, being three 

 or four times as broad as thick : some of 

 them seem scarcely bigger than the 

 thread of a silk-worm, and are surpris- 

 ingly flexible. If the two ends of such 

 threads are knotted together, they may 

 be drawn and bent, till the aperture, or 

 space in the middle of the knot, does not 

 exceed one fourth of a line, or one forty- 

 eighth of an inch in diameter. Hence 

 M. Reaumur advances, that the flexibili- 

 ty of glass increases in proportion to the 

 fineness of the threads; and that, proba- 

 bly, had we but the art of'di awing threads 

 as fine as a spider's web, we might weave 

 stuff's and cloths of them for wear. Ac- 

 cordingly, he made some experiments 

 this way ; and found that he could make 

 threads fine enough, viz. as fine, in his 

 judgment, as spider's thread, but he could 

 never make them long enough to do any 

 thing with them. 



DUEL, a single combat, at a time and 

 place appointed, in consequence of a 



