SCIENCE. 



litle 



Description 

 of Dr. 

 Black'* 

 simple and 

 delicate 

 balance. 



correct view of the mailer; as appears from a careful 

 investigation of the pr.H.^ l, v M. M. Di.ru-n and 

 Colladon of (u-neva. I'hese gentlrnu M observed that 

 the iron wheel was covered with small fr.iymenU of 

 the steel, and that these fragments were as hard as the 

 best tnnprrrd steel, which proved that it could not 

 have been aofttiu-d by lu-.*t. They found also tli.it, 

 with a velocity of thirty- four feet per second an iron 

 whirl was easily cut with a steel graver without any 

 reaction on the graver. With a velocity of thirty-four 

 feet nine inches, the iron was less attacked, and the 

 graver began to experience an impression from the 

 iron. With a velocity of thirty-five feet one inch, the 

 action of the iron on the graver was decided, and in- 

 creased with grsater velocities, till, at a velocity of 

 seventy feet per second, the iron was no longer marked 

 by the steel, while the steel was cut with the greatest 

 violence. M. M. Darien and Colladon are of opinion 

 that the whole effect is directly mechanical, arising 

 from the brittlene c s of the steel, which is torn asunder 

 before it has time to introduce itself amor;; the par- 

 ticles of the soft iron, a phenomenon which they con- 

 sider as analogous to the penetration of wood by a ball 

 of tallow discharged from a gun. 



U ..en a wheel of pure copper was used, no effect 

 was produced upon the graver; but what was very 

 remarkable, little or no heat was generated when Jiles 

 and steel springs mere held .firmly against the revolving 

 copper wheel. See the Bibl. Universclle, April 1824, 

 p. 283 290, or an abstract of the Memoir in Dr. 

 Brewster's Journal of Science, Vol. I. p. 341, October 

 1824. 



3. Description of Dr. Black's simple and delicate 

 Balance. 



The description of this very simple and accurate 

 balance has been recently published by James Smithi- 

 son, Esq. to whom it was communicated in a letter 

 from Dr. Black himself. The beam of the balance 

 was a piece of fir wood, of the thickness of a shilling, 

 about a foot long, three tenths of an inch broad in the 

 middle, and l tenth at each end. This beam is 

 divided by transverse lines into 20 parts, or 10 parts 

 on each side of the middle. Each of these is divided 

 into halves or quarters. Across the middle of the 

 beam is fixed with sealing wax one of the smallest 

 needles that could be procured, to serve as a horizon- 

 tal axis. A piece of plate brass has its two ends 

 bent up, so as to form three sides of a cube, and on the 

 two edges of this piece of brass, ground on a flat 

 hone, the needle rests as on a fulcrum. These edges 

 are only 1 .', or 2-10ths of an inch above the table, so 

 that the beam has very little play. 



The weights which Dr. Black used were one glo- 

 bule of gold, which weighed one grain, and two or 

 three others which \veighed one tenth of a grain each. 

 He used also a number of small rings of fine brass 

 wire, made by coiling it round a thicker brass wire 

 in a close spiral. The extremity of the spiral being 

 tied hard with a waxed thread, the covered wire was 

 put into a vice, and a sharp knife being applied, and 

 .struck with a hammer, a great number of the coils 

 were cut through at one stroke, and they were as 

 exactly equal to eaeh other as could be desired. Those 

 which Dr. Black used happened to be one-thirtieth 

 of a grain each. By means of these weights placed at 

 different distances from the middle of the beam, he 

 could weigh any little mass from one grain, or a little 



TOL. XVII. PABT II. 



Cui 



more, to the twelve* hundredth part of a grain. Bee 



the Annuls of PkUotoph ' ol. X. p. 52. 







4. DttcriptiOH i'J u C/tintse Manglt. **^~*~** 



This very ingenious and simple piece of mechanism DaMitpdai 

 is represented in Plate CCC.( I XXXV. Fig. 27, 28, fCMaan 

 which is taken from a model of it executed by Andrew 

 Waddel, Ktq. of Hermitage Hill, a few days after be 

 had seen it at work in Canton in 1786. Fig 27 ahowa 

 the stone or mangle at rest, standing on its end on 

 the floor, with the roller and cloths coiled round it 

 previous to the commencement of the operation. The 

 house was paved with tiles, as shown at A, and on the 

 floor watt a concavity B, lined apparently wit!) hard 

 wood. The roller C, with the cloth wrapped round 

 it, was laid in the concavity B. The weight on which 

 the whole operation depended was a stone D, appar- 

 ently sandstone, weighing from 10 to 12 cwt. and 

 shaped so as to stand on either end, as the workman 

 chooses, vhen he wishes to examine his work, or 

 when he finishes it. By resting on the framing of 

 bamboos E, E, E, he steps on the uppermost end of 

 the stone D, and allows its under surface to fall 

 gently on the roller C. He is now in the position 

 shown in Fig. 28, when he presses alternately with 

 each foot so as to give the stone an alternate motion, 

 which causes the roller C, with the cloth, to pass over 

 the whole concavity B of the floor, and with the de- 

 gree of velocity which he chooses. 



Since Air. Waddell communicated to the writer of 

 this article the preceding drawing and description, we 

 have obtained possession of a Chinese drawing of the 

 same apparatus, in a series of paper hangings for 

 rooms. We have given an exact copy of it in Fig. 29. 



5. Mr. Babbage's Calculating Machinery. 



Although pieces of mechanism for performing par- Mr. Bab. 

 ticular arithmetical operations have been long ago b*g*' ' 

 constructed, yet all these sink into insignificance when 

 compared with the extraordinary machinery recently 

 invented by Mr. Babbage. As no description of this 

 machinery has yet been published, we are of course 

 not able to convey any idea of it to the reader ; but the 

 effects which it is capable of producing are so wonder- 

 ful, that a general notice of them cannot fail to be ac- 

 ceptable. 



.Mr. Babbage's first object was to produce printed 

 copies of any mathematical tables, vciihout the possibility 

 of an error existing in a single copy. Although this 

 was to be effected by machinery, yet certain prelimin- 

 ary calculations were necessary, and the machinery re- 

 quired to be set to these numbers at intervals ; but in 

 some cases, when it is once set, the machinery will 

 continue working to the end of the tables. 



In order to demonstrate the practicability of bis 

 machinery, Mr. Babbage has constructed a small en- 

 gine, by which the following table was computed from 

 the formula, j ! -f. j-)-41. 



41 

 43 

 47 

 53 

 61 

 71 

 83 

 VI 

 113 



131 

 151 

 1T3 

 197 

 823 

 251 

 281 

 313 

 347 



383 

 421 

 461 

 5S:i 

 547 

 593 

 641 

 641 

 743 



797 



853 



911 



971 



1033 



1097 



1163 



)-.'Jl 



1301 



1373 

 1447 

 I5t3 

 1601 

 1681 

 1765 

 1847 

 1933 

 2021 



These numbers, as soon as they were calculated, 



