Mr. G. W. Royston-Pigott on an Aplanatic Searcher. 259 
applying a similar correction to the observing-objective. 
he chief results hitherto obtained may be thus sum 
whilst observing with a half-inch objective with a power e 
hundred diameters, and found it two-tenths of an inch increase; 
stituted for the deep eye-piece formed of minute le nd gu 
h a min tely perforated cap. e writer lately exhibited to 
Messrs. Powell an land a brilliant definition, under r 
true image of the other. But the upper or lower set may be sepa- 
* Alluded to by Mr. Reade, F.R.S., in the ‘Popular Science Review’ for 
April 1870. id 
