THE MICROSCOPE AND HOW TO USE IT. 169 



But they came again, and by-and-bye my surgery did not avail. 

 They increased, and the buoyancy would raise it to the surface, 

 and the little sufferer, despite all help, would float. And so it was 

 on the last day of February, at an early hour, 1 found poor Hippie 

 afloat on her beam ends and dead. I had her alive just four 

 months, and the above is but a tithe of what might be told of her 

 pretty ways. 



Zbc riDicroocopc anb bow to U6C it. 



By V. A. Latham, F.M.S. 



Part XL — Injecting, etc. (continued). 



Sterling's Constant Pressure Apparatus (Plate XIV., Fig. 4). — 

 Ciet a large, wide-mouthed bottle and a smaller one ; have these 

 well fitted with corks. In the larger cork bore four holes,* and in 

 the smaller one two. Into two of the four holes in the larger 

 cork fit two straight tubes, one passing nearly to the bottom of 

 the bottle, the other passing for a distance of half-an-inch only 

 through the cork. On this latter tube should be a stop-cock, and 

 fitted above it a mercurial manometer by which the pressure is 

 measured. This is simply a flattened S-shaped tube, turned 

 through a right angle, one bend of which is filled with mercury. 

 Behind this tube is placed an index board marked off in \ inches. 

 Into the other hole fit a couple of tubes bent at right angles, each 

 tube passing through the cork and projecting into the bottle for 

 about \ inch, one of them having a stop-cock on the horizontal 

 part of the tube. Into the two holes in the cork of the smaller 

 bottle are fitted bent tubes, one of which passes to the bottom of 

 the bottle, the other passing in for only \ inch. A tin cylinder 

 holding a couple of pints of water is hung over a pulley fixed to 

 the ceiling of the room by means of a cord. It can be raised or 

 lowered at pleasure. An India-rubber tube is carried from the 

 bottom of the tin to the straight tube which passes to the bottom 

 of the larger vessel. Pressure from a water-main may be used in 

 place of this last piece of apparatus. From the open bent tube 



* The fuurth tube, with the stop-cock for allowing ingress and egress of air, 

 is not represented in the diagram. 



