On a Portable Form of Aeroscope, &c. By Dr. Madclox. 341 



has passed through the aeroscopes ; the air and water descend 

 together pretty uniformly through the index tube, where the rate 

 of flow is estimated, and pass into the bladder on the floor, the 

 collected air soon passing off by its proper tube into the sus- 

 pended bladder. This eventually gets filled, or if not quite filled, 

 by the air-pressure, the stopcock of the bladder on the floor is turned 

 off, and slight pressure made by hand. The stopcock is then turned 

 on again and the stopcock of the air-bladder closed, released from 

 its tube, and the air discharged ; the bladder is then refixed as 

 before, and the suction of the trompe continued until the water is 

 expended, or as long as required. No. 1 and No. 2 bladders 

 can be easily made interchangeable by temporarily suspending the 

 action of the siphon. The capacity of the large air-bladder being 

 known, and it being filled once or oftener, furnishes a rough esti- 

 mate of the air drawn over. The time occupied can be also noted. 

 The bladders are rendered flexible by being well impregnated with 

 glycerine. 



N.B. — Since exhibiting the double form of aeroscope and 

 aspirator I have constructed an instrument in which the aeroscope 

 and aspirator are combined in one. For compactness it has advan- 

 tages. It was exhibited in action at the Scientific Meeting of the 

 Society on the evening of May 2nd. 



The instrument consists of two large brass tubes A, B (fig. 59), 

 which screw together air-tight. A has cemented into it a small 

 glass funnel 0, drawn to a point. B is rather longer than A, and 

 has a small brass tube D, open at 

 both ends, soldered obliquely into it. Fig. 59. 



Near the inner end of this tube a 

 portion is cut away, into which 

 freely passes the fine end of another 

 smaller tube E, which is fitted air- 

 tight into the closed end of B, and 

 projects into the tube, so as almost to ^ 



touch the opposite side. The cover- 

 glass with sticky material is held in a small cradle near to the fine 

 orifice of the funnel. Air enters by C, and water by E, which by 

 gently dropping or escaping by the fine orifice into I), sucks the air 

 through the funnel, and they both together pass off through the outer 

 end of D, to which is attached the looped indiarubber tube, as in the 

 double form. It can be used with the funnel looking downwards 

 or horizontally. To increase the fall and the air spaces between 

 the drops of water passing through the index tube, an upright, 

 about 15 in. high, was screwed to one side of the base board. 

 To the top of the upright was hung an oblong tin vessel (box), 

 into the lower end of which was fixed a small stopcock connected 

 with the projecting end of the tube E, by a short caoutchouc tube. 



