232 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
MICROSCOPY. 
[An abstract of Dr. Clifford Mercer’s important paper on “ Aperture,” 
referred to in the President’s Annual Address, is unavoidably postponed 
to the next number. — Editor, Journ. R.M.S.] 
A. Instruments, Accessories, &c.* 
(3) Illuminating and other Apparatus. 
Spider-Lines.f — Mr. F. L. 0. Wadsworth reports very favourably 
on his experience of quartz-fibres instead of silk or spider threads in the 
cross lines of optical instruments. The transparency of the quartz-fibres 
is removed by silvering them by any of the ordinary methods. The 
difficulties arising from the hygroscopicity and semi-translucency of both 
* This subdivision contains (1) Stands; (2) Eye-pieces and Objectives; (3) Illu- 
minating and other Apparatus; (4) Photomicrography; (5) Microscopical Optics 
and Manipulation ; (6) Miscellaneous. 
f The Microscope, December 1897, p. 157. 
