ZOOLOGY AND I30TANY, MICROSCOPY, ETC. 95 



MICROSCOrY 



A. Instruments. Accessories, etc.* 

 (1> Stands. 



Improved Water Microscope, f— E. M. Xelson writes : " Stephen 

 Gray, in 1696, invented a water IMicroscope, which consisted of a metal 

 plate with a small hole in it. A drop of water placed in the hole formed 

 the lens; there was a spike npon which to impde an object, and a 

 focnsing screw. Mr. T. Court has found, and kindly sent me an account 

 of another form of Gray's Microscope, due to an anonymous author at 

 Cambridge in 1750. In'tig. 1.5 B C is a metal plate with thirteen holes 

 of different sizes drilled through it. These, filled with drops of water, 

 form lenses of various powers. F D is a spring holder for the needle 



Fig. 15. 



A E : this, in its normal position, lies close against the lens plate. In 

 order to focus an object upon the needle-point, it is only necessary to 

 insert the wedge I at H to the proper distance. The needle may be 

 changed for a pair of forceps K. It is stated that this Microscope 

 "will afford a great deal of pleasure to any curious inquirer, especially 

 as the purchase of it will not much affect the pocket." So far as I am 

 aware this Microscope has not been lecorded in any list of ancient 

 instruments." 



Watson and Sons' "Bactil" Microscope. J— In this instrument 

 (fig. 16) the body-tube is Ih in. in diameter, is suitable for photo- 

 graphic purposes, and the draw-tube divided to millimetres. The coarse- 



* This subdivision contains (1) Stands ; (2) Eye-pieces and Objectives ; (3) 

 Illuminating and other Apparatus ; (4) Photomicrography ; (5) Microscopical 

 Optics and Manipulation ; (6) Miscellaneous. 



t English Mechanic, xciv. (1911) p. 348 (1 lig.). 



X Watson's Special Catalogue, 1912, 8 pp. (4 figs.). 



