286 



SUMMARY OF CUREENT RESEARCHES RELATING TO 



and that along the horizontal edge 7 • 8. An estimate can be very- 

 well made within a tenth (that is to • 2 mm.) which is sufficiently near. 

 It may sometimes happen with large preparations and slides of 

 ordinary size that the corner to be marked lies outside the divisions. 

 I therefore mark the position of the opposite diagonal, and put an 



angle round the fraction thus : 



106 



47 



I have been able to convince myself by trials that divisions which 

 are good for one Microscope are equally good for others similarly 

 ^arranged, and that therefore the contrivance is a practical one." 



Stokes's Fish-trough,* — A. W. Stokes describes a simple appa- 

 ratus for aerating living fish whilst under observation. It is shown 

 in perspective at fig. 35, and in longitudinal section at fig. 36, 



Fig. 35. 



a, a being two wedge-shaped slips of wood well soaked in paraffin 

 wax to render them waterproof, 6, fe, two 3x1 glass slips, so 

 arranged as to form, with the wood slips, a wedge-shaped glass box. 

 The larger end of this box is inclosed in a short piece of indiarubber 

 tube c, and this tube is closed by a cork. A short piece of glass d is 

 fixed inside about midway between the glass sides of the box, so that it 

 will form a shelf upon which the fish's tail may be during examina- 



FiQ. 36. 



tion, as shown in fig. 36. At either end of the box are fitted two short 

 glass tubes e e, which when the instrument is in use are respectively 

 connected by indiarubber pipes with bottles at different levels, to 

 obtain a circulation of water. 



Nelson - Mayall Lamp. — At the Society's meeting in January, 

 Mr. J. Mayall, jun., exhibited the modified form of Nelson's lamp, f 

 shown in fig. 87. The modifications consist (1) in making the 

 oil-well circular instead of square, so that the standard passes con- 

 veniently through the centre, and the well carrying the lamp can 



* Journ. Quek. Micr. Olub, i. (1884) pp. 322-3 (2 figs.), 

 t See this Journal, ante, p. 125, 



