K 
188 Transactions of the Royal Microscopical Society. 
In the ' Quarterly Journal of Microscopical Science ' some one 
has lately said Dr. Pigott has given up the use of the searcher ; 
a more silly and gratuitous statement could not well be made by 
an anonymous writer. On the contrary, I am trying very much 
to improve and simplify it. I have adapted one especially for a 
Gundlach. It is a 16th (English 13th). My searcher deepens its 
focal distance, enables me to use low eye-pieces instead of deep 
ones (which I hate). I get jet-black edgings with scarcely any burr 
of light. I have seen as well with this combination as with any 
glass I have ever tried. I can vary all the corrections at will, far 
beyond the limits of mere " collar " action. I change the colouring ; 
blacken the shadows ; embrilliant the bright focal points of isolated 
refracting particles ; evanish the focal plane more suddenly. In 
fact, as soon as the corrections become as perfect as the combina- 
tion admits, less light is required. Wasted light is concentrated. 
Eidge after ridge glows into focus as each flashes into the focal 
plane of vision. A rolling line of brilliance, the locus of the most 
exact definition, moves backwards and forwards along a curved 
surface, with the slightest touch of the fine focus wheel. The 
object, in a manner, becomes as it were self-illuminated. And in 
proportion as less intrinsic light is employed at the origin of light, 
the difiraction errors are correspondingly reduced, and may be in 
some cases destroyed. 
I may be permitted to illustrate these points by actual cases. 
I. A gentleman and his wife on a visit to my house made the 
following note in his own handwriting, and I had nothing whatever 
to do with the description or diction ; only with the adjustments 
and illumination. 
" JDegeeria domestica. 
" Paraffin lamp, direct light illumination, 1-| inch open condenser.* 
Gundlach's with new correcting lenses and A eye-piece : 6 inches 
tube : blue glass shade. 
" Glass under-corrected to show upper surface. 
" (1) At lowest focus : i. e., focus for lowest surface. Eose colour 
on green ground. Longitudinal beads and ' bugles,' or short tubes. 
" (2) Slightly higher focus. White ground. ' Tubes ' dark 
purple with light green, and pink edges ; indistinct pale spaces 
between the * tubes.' 
"(3) Slightly higher focus. Yery faint 'beads' transverse 
between the ' tubes ' ; ground variegated in colour ; ' beads ' 
not separated, apparently joined; tubes pale green in colour. 
(Eecorrected by screw-collar.) 
" At upper focus. Scale broken, and in part obliterated. Grround 
yellowish green. Clots of longitudinal beads, bright or blood red. 
* Without U-shaped stop or any stop at all. 
