PLATE 

 I'CCCLXXXVI 

 Fy*. 86, 27. 



The in- 

 flaming 

 condenser. 



Fig. 28. 



To support 

 a ball on a 

 jet of air. 



SC I E 



pieces of machinery. We do not know who invented 

 it, and we are not aware that it has been any where 

 described. 



Take a stiff piece of card, or sheet copper, or brass, 

 about two and a half, or three inches in diameter, and 

 cut it out spirally, so as to resemble a snake, having its 

 head at b and its tail at a, as in Fig. 6'. The body 

 having been well painted, so as to resemble a snake, 

 take it by the two ends a h, and draw out the spiral 

 till the distance a b is 6' or 7 inches, as in Fig. 27- Ha- 

 ving provided a slender piece of wood c d, on a stand d, 

 and fixed a fine sharp-pointed needle at its summit, 

 push the rod c d up through the spiral, and let the end 

 a of the spiral rest upon the summit of the needle. 

 The apparatus being now placed as near as possible to 

 the margin of the marble shelf above the fire, the snake 

 will begin to revolve in the direction of its head ; and 

 if the fire is strong, or the current of heated air which 

 ascends from it is made powerful by two or three per- 

 sons coming near it, so as to concentrate the current, the 

 snake will revolve with very great rapidity. The rod 

 a b should be painted so as to resemble a tree, which 

 the snake will appear to climb. 



If the body of the snake, in place of going from 

 right to left, as in Fig. 26, goes from left to right, it 

 will move in the contrary direction when put up. 

 When a right and a left handed snake are put up near 

 one another, the interfering shadows of them produ- 

 ced by one or more strong lights has a very singular 

 effect. 



If a small steel pivot is thrust up through the ex- 

 tremity of the tail a, the snake may be suspended at 

 the end of a magnet by the steel pivot, the quantity 

 of steel being made just sufficient to enable the mag- 

 net to support the weight of the snake. In this case 

 there is no need of the stand c d. 



3. The Inflaming Condenser. 



It has been long ago observed, that when the ball of 

 an air gun was filling with condensed air by means of 

 the syringe, a flash of light was often perceived. It has 

 also been found, that the thermometer always rises in 

 condensed air. 



These results have given rise to a small condenser, 

 A B, Fig. 28, made of brass, and wrought by the pis- 

 ton CD. A small piece of amadou, which easily takes 

 fire, is placed in the end B, which screws off rapidly, but 

 at the same time is air-tight. The piston C D 

 being pushed down with great smartness, the heat 

 disengaged by the condensation of the air inflames the 

 amadou at B. By screwing off the end B quickly, a 

 match may be lighted at the amadou. 



This apparatus has been constructed on such a 

 scale as to inflame gun-powder placed in the end B. 



4. To support a Ball on a Jet of Air. 



Every person must have seen the experiment of sup- 

 porting, for any length of time, a ball upon the sum- 

 mit of a jet of water. The same may be done upon 

 the summit of a jet of condensed air. It has been long 

 a practice of school-boys to perform this experiment in 

 a very dexterous manner by means of a quill, or 'the 



NC E. 



stalk of a tobacco-pipe and a pea ; and some of them Science 

 often acquire the art to such a degree, as to make the "* 



experiment a very surprising one. When a jet of con- <_ _j 



densed air is used, tlie ball follows the play of the jet 

 With mure regularity. 



If the condensed air is coal or oil gas, as in Mr. 

 Gordon's portable lamp ; and if the gas is set on fire, 

 the phenomenon of the supported bail is very curious. 

 This experiment was, we believe, first made by \Ir. 

 Deuciiar. 



5. Description of a Rotatory Gas Burner. 



Various attempts have been made to construct a gas Description 

 burner which should revolve, upon the principle off arota - 

 Barker's mill, by means of the reaction of the gas issy- tor y 8 as 

 ing under the ordinary pressure at which it is burned. 

 If the place round which the motion is performed is. 

 an ordinary gas-tight joint, the friction is so great that 

 a motion of rotation cannot be obtained unless tlve 

 gas has been greatly condensed so as to issue under 

 the pressure of many atmospheres. A rotatory bur- 

 ner of this description was made last year by Mr. 

 Deuchar, but it was nothing more than a philosophi- 

 cal experiment quite inapplicable to gas as it is ge- 

 nerally used. 



The rotatory gas burner, which is represented in 

 Plate CCCCLXXXVI. Fig. 29. is the invention of Mr. PLATE 

 Nimmo, brassfounder in Edinburgh. It displays great CCCCLXXXVI. 

 ingenuity, and revolves by the reaction of gas issuing Fig. 29. 

 at the ordinary pressure. 



In the section of it in Fig. 29, PQR is the gas 

 tube communicating by its lower end PQ with any 

 gas pipe. This tube, which is conical at its upper 

 end R, terminates in a sharp pivot at R, and has se- 

 veral large holes a made in it near the top, so as to 

 allow the gas to escape. On the outside of the tube 

 PQR, and fixed to it at PQ is the water tube 

 ABCDPQ which is filled with water. These parts ef 

 the burner are all stationary. 



The revolving part consists of two horizontal tubes 

 crossing one another at right angles. Only one of 

 these tubes EF is seen in the section. These tubes 

 communicate with the vertical tube GHMN, the lower 

 end of which MN is open, and is immersed in the 

 water tube ABCD, the whole resting upon the pivot 

 above H, and revolving upon it as a centre. This re- 

 volution is effected in the following manner. The gas 

 ascending the tube PQR escapes through the openings 

 in it at a, and being prevented by the water within 

 the tube GHMN from getting out at its open end 

 MN, it fills the tubes EF, and issuing at the holes 

 h, h at their extremities, its reaction upon the opposite 

 sides of the tube produces a horizontal rotatory mo- 

 tion, the vertical tube GHMN revolving freely in the 

 water in the tube ABCD. 



If the contrivance now described formed merely an 

 elegant addition to our gas light apparatus, it would 

 even in this point of view possess considerable in- 

 terest ; but there is reason to think that by a proper 

 adjustment of the velocity of rotation to the quantity 

 of gas discharged, the flame may be supplied with the 

 requisite quantity of air more perfectly than can be 

 done in a stationary burner. If this shall turn out to 

 be the case, the rotatory gas burner may be the most 

 economical contrivance for burning gas. 



