*586 



SCIENCE. 



Science^ were exhibited to the eye on two opposite sides of 



Curiosities t ne machine, to the persons employed to copy them. 



'" In the early numbers of the table the copyist rather 



V *''""Y" ^ more than kept pace with the engine; but when five 



figures were required, the machine was at least equal 



in speed to the writer. At another experiment with 



it, thirty-two numbers were calculated in two minutes 



and thirty seconds, and as these contained eighty-two 



figures, the engine produced thirty-three figures every 



minute. At another time it produced forty-four 



figures in a minute. 



Although this machine contains many wheels, yet 

 the same parts are frequently repeated, and only a few 

 wheels move at the same time. Notwithstanding the 

 number of the wheels employed, yet, by a peculiar 

 contrivance, any error produced by accident, or by 

 any slight inaccuracy in one of the wheels, is corrected 

 as soon as it is transmitted to the next. 



Mr. Babbage has constructed a working model of 

 the machine for composing with types. When put up, 

 it will contain about 30,000 types, which are set in 

 their places by children, but the person who attends 

 the engine has a method of ascertaining, in less than 

 30 minutes, whether or not any one individual type of 

 the number is misplaced. 



During the progressive improvement of the ma- 

 chinery, Mr. Babbage was led to a new arrangement, 

 by which an engine might be constructed which should 

 calculate tables of other species whose analytical laws 

 were unknown. 



It is gratifying to find that government have libe- 

 rally granted 1500 to Mr. Babbage to enable him to 

 complete one of these machines on a great scale. 



6. Description of Richardson's Lifting Plug, 



Description In elevating large stones, a small piece of iron called 



of Kichard- a lev/is has been generally employed. A cylindrical 



S hD llfnng hole cut in the stone, and made wider below than 



above, receives the lewis, or a cylindrical piece of iron, 



which is made to widen at its lower end, so as to fill 



the enlarged part of the cylindrical bore. The lewis, 



therefore, cannot be pulled out of the stone without 



carrying away a portion of it ; so that if the stone is 



tough, the mass may be elevated by applying the 



power to the upper end of the lewis. 



The lifting plug invented by Mr. Richardson of 

 Keswick, is a much more simple and efficacious con- 

 trivance. A small cylindrical hole, about two inches 

 deep, is cut perpendicularly, or nearly so, out of the 

 stone by the common steel boring chisel of masons. A 

 common cylindrical plug of iron, about a 20th or 30th 

 part of an inch less in diameter than that of the hole, 

 is now driven into it about an inch deep, by two or 

 three blows of a hammer ; and with no other fastening 

 the heaviest stones may be raised, and the largest 

 masses of stone torn up from the ground. The cause 

 of the firm adhesion of the iron plug to the stone, is 

 no doubt the elasticity of the stone, which grasps, as 

 it were, the plug in the same way as wood does a po- 

 lished nail which is driven into it. When it is re- 

 quired to detach the plug from the stone, nothing more 

 is requisite than a sharp stroke or two from a hammer. 

 The principle on which this experiment depends may 

 find numerous applications. By the same means, a 

 vessel of any size might be moored, and masses of stone 

 held together as firmly as if they wer e of one piece. 



OPTICS. 

 In our Article on OPTICS, and in our Articles on 



the KALEIDOSCOPE, the MICROSCOPE, and the TELE- Science, 



SCOPE, we have d escribed several of the most popular Curiosities 



and amusing instruments which depend upon light 



and vision. Several very curious instruments and ex- v "" ""V"""' 



periments, however, still remain to be described under 



the present head. 



1. The Thaumatrope. 



The thaumatrope, (or the ivonder turner, from 6xvftx The Thau- 

 a wonder, and T^TFU to turn,) a very ingenious philoso- matrope. 

 phical toy, invented, we believe, by Dr. Paris, is found- 

 ed on the well known optical principle, that an impres- 

 sion upon the retina continues for about the eighth part 

 of a second after the object which produced it is with- 

 drawn. The luminous rings formed by the whirling of 

 a burning stick in the dark are well known, and Ho- 

 mer has availed himself of the same principle in his 

 description of the lengthened shadow of the flying ja- 

 velin. 



The thaumatrope consists of a number of circular 

 pieces of card, about two and a half inches, in diameter, 

 which may be twirled round with great velocity by 

 the application of the fingers to pieces of silk string at- 

 tached to two opposite points of their circumference. 

 On each side of a card is painted a .part of a picture, 

 so that if we could see both sides at once, the two 

 parts of the picture would form a whole picture. For 

 example, in PI. CCCCLXXXVI. Fig. 1, we have shown PLATE 

 two sides of a card, on one of which is a cage, and CCCCLXXXVI. 

 on the other a bird. If we now take hold ot each of ^8- * 

 the silk strings A and B, between the fore-finger and 

 thumb of each hand, and put it into a twirling motion, 

 the bird and the cage will appear to the eye at the same 

 moment, in consequence of the impression of each con- 

 tinuing upon the retina for a short space of time. The 

 following are some of the other devices on the cards 

 of the thaumatrope. 



A rose tree, with a garden pot on the reverse. 

 A horse, with a man on the reverse. 

 A leafless branch, which becomes verdant on the 

 twirling of the card. 



A female in one dress on one side, and another dress 

 on the other. 



The body of a Turk, with his head on the reverse. 

 The Watchman's box on one side, and himself on 

 the other. 



Harlequin and Columbine on different sides, appeal- 

 together by the revolution of the card. 



A comic head on one side, which, on turning round, 

 becomes invested with a wig. 



A man sleeping, and awakened by being turned 

 round. 



The principle of the thaumatrope may be extended 

 to many other devices. Parts of a sentence may be 

 written on one side, and the rest of the sentence on the 

 other ; and we may even put halves of the letters on 

 one side, and the other halves on the other side. 



Those who have used the thaumatrope, must have 

 been dissatisfied with the general effect of the two 

 combined pictures. There is a hobbling motion arising 

 from the imperfection of the method adopted to produce 

 the rotatory motion, which entirely destroys the effect; 

 and it is perfectly clear that the rotatory motion 

 should be produced by quite different means. If 

 strings are adopted, they ought to be attached to the 

 circular pieces of card, so that the axis of rotation 

 should be in the plane of the card ; but a solkl axis of 

 rotation is decidedly preferable. See Dr. Brewster's 

 Journal of Science, No. VII. 



