On a Portable Form of Aeroscope, &g. By Br. Maddox. 339 



Fig. 58. 



When long examinations are needed, it wonld be better to use a 

 larger form of apparatus, or at any rate a larger supply of water 

 and some form of meter to register the exact amount of air trans- 

 mitted in a definite time. 



The aeroscope A (fig. 58) is made of a short wide glass tube, brass 

 mounted at each end, and rendered air-tight by indiarubber washers. 

 The parts are separable. The brass tube that holds the short 

 ground neck of the glass funnel 

 inside the cap, supports a bent 

 wire platinum cradle, which car- 

 ries a thin glass cover, smeared 

 in the centre of the surface to- 

 wards the funnel, for about half 

 an inch, with glycerine simply, 

 or mixed with gum or glucose. 

 The brass cap at the opposite 

 end to the funnel is pierced by 

 a short metal tube 3-8ths of an 

 inch bore. 



The aeroscope B is a turned 

 boxwood box, the top unscrew- 

 ing below the shoulder — one of 

 the boxes sold by chemists made 

 to contain a stoppered short 1- 

 ounce or 10- drachm bottle, the 

 bottle being removed; the bottom 

 is turned out to fit a small 

 pointed conical glass funnel, 

 which is cemented into the 

 box; a small metal cradle, the 

 spring sides of which press 

 against the inside of the box, 

 carries the thin cover - glass 

 smeared with some sticky ma- 

 terial, and can be pushed nearer 

 to the point of the funnel or 

 withdrawn as required, being 

 usually placed about the 1-3 0th 

 of an inch. The distance much 

 depends upon the force of suc- 

 tion of the aspirator. The aper- 

 tures of the funnel vary from 



about the l-50th to the l-80th of an inch. The top of the box 

 has screwed into it a short metal tube. The aspirator or trompe 

 is a small conical, round-shouldered glass vessel, of about one 

 ounce capacity, open at both ends. On the larger end fits tightly 



z 2 



