JOURNAL OF MICROSCOPICAL SCIENCE. 
EXPLANATION OF PLATES VIII AND IX, 
Illustrating Dr. Royston-Pigott’s Researches. 
PLATE VIII. 
Plate VIII is intended to represent the working powers gained by the use 
of the Aplanatic Searcher by means of comparative outline drawings of a 
given “scale” taken by Mr. Aldous with the camera under the magnify- 
ing powers and objectives indicated. 
Fig. 
1.—The standard appearance of the Podura under the 3, j;, and } Powell 
and Lealand objectives. 
2.—Resolution of the lower beads of Podura. 
3.—The beads of the upper stratum. 
4.—Comparative magnifying power of the + objective with the searcher, 
and also in the ordinary way with a “third” eye-piece, C, of 1 
inch focal length. 
5.—General appearance of the wavy markings of the Podura, consisting of 
beaded ribbing faintly visible here with a pocket-lens. 
6.—Both sets of beading exhibited at once. 
7, 8.—Ordinary and extraordinary appearance of Lepisma. 
PLATE IX. 
This Plate shows the image-test arrangements of the objectives and object 
of which a miniature is desired, and also the construction of the searcher. 
M. The divided milled head of the traversing aplanatic searcher, consisting 
of separable lenses, A, B, having a variable interval, 2’, between them. 
The searcher traverses the draw tube, into which is fixed the eye- 
piece E. R, M are adjusting milled heads of the stage supporting 
the image objective O' (fig. 1 a). 
O, O’, fig. 1, fig. 1 a, are the objective to be tested and the miniature-form- 
ing =}; immersion objective, giving an image a of the object 0, or 
double disks A, illuminated by a lamp, 6. 
y represents the focal adjustment, and 
B the aberrameter inserted into the nose of the microscope containing two 
revolving disks forming central and peripheral stops. 
Fig. 2 represents the course of the rays from the object Q to the last focal 
image g’ p” erected. 
