Intelligence and Miscellanies. 201 



In front of the cistern may be seen an inverted brass kettle, 

 held firmly to a wooden plank by straps and iron screws. 

 This kettle covers a circular hole in the plank. The hole is 

 somewhat less in diameter than the kettle inside, so as to 

 leave a bearing for the brim of the latter. Between the brim 

 of the kettle and the margin of the hole, cut in the plank, 

 the margin of a disk of sole leather is included, at about half 

 an inch from its circumference all round, in such a manner as 

 4o form an air tight juncture. The leather is perforated at 

 the centre, and is pressed between the summits of two per- 

 forated leaden hemispheres, by a rod of iron which passes 

 through the perforations in them, and in the leather. The 

 compression is effected by means of a screw and nut, and a 

 shoulder on the iron rod. The rod thus fastened to the 

 leather disk, is connected with the bent lever, b, I, which is 

 carried under the cistern, and being bent at right angles, is 

 flattened so as to form a treadle. When the treadle is forced 

 down by the foot, the arm connected with the rod rises, and 

 causes the leather to be bulged up into the kettle ; when the 

 pressure of the foot ceases, the weight, w;, suspended from 

 the lever, causes the descent of the rod, and the leather is 

 bulged downwards, so as to cause air to enter the kettle, 

 and to be expelled from it, successively. 



Into the bore of the cock, which extends from the upper 

 surface of the kettle to the arched pipe, h k, there is a valve 

 opening outwards. Within the pipe in the form of an elbow 

 on top of the kettle in front of this cock, there is a valve 

 opening inwards : it is through the valve last mentioned, that 

 the ingress of air takes place, while the egress is effected 

 through the other. 



In order to put this apparatus into operation, the kettle,* 

 cistern and upper air cells must be filled with water, until it 

 is about an inch deep on the shelves, A A, the lower air cells 

 remaining full of air. Bell glasses, or other vessels, being 

 plunged in the well, filled with water, and inverted and pla- 

 ced, while full, over one of the holes, h, on the sliding shelf, 

 B, are afterwards easily filled with any gas ; for any gaseous 

 fluid escaping from a retort beak, or from a tube, will be ea- 

 sily caught in the cavity, excavated in the wood of the lower 



* It is requisite to the operation of the bellows, that the kettle be filled with 

 water first, otherwise the air remaining in it, will, by its elasticity, diminish 

 the effect. 



Vol. XIV.— No. 1. 26 



