PROGEESS OF MICKOSCOPICAL SCIENCE. 35 



deservedly popular. The use of immersion objectives for all high 

 powers seemed to be assumed by all members as a settled question. Few 

 members, on the other hand, fall into the present fashion of high-power 

 objectives, preferring to use lenses of yV^h or ^th, and downward, 

 and gain greater amplification by other means than by reducing the 

 nominal focus of the objective. 



A Micro-Telescope. — Dr. Josiah Curtis exhibited a micro-telescope, 

 or microscope and telescope combined, made to his order by ToUes. 

 It is an ordinary Cutter's clinical microscope, fitted with an extra 

 tube carrying an object-glass of 1-inch linear aperture and 6-inch 

 focus, to which objective the compound microscope acts as an erecting 

 eye-j)iece. Furnished with a proper support this makes an admirable 

 pocket-telescope, defining well at powers of forty or fifty diameters. 



Mounting very Loio Objectives. — Mr. Tolles had moimted a 2^-inch 

 lens with the Society screw on each side of the shoulder, so that it can 

 either be screwed on in the usual position, or passed up into the body 

 of the instrument and fastened there, giving, by approaching the eye- 

 piece, about the j)ower of a 4-inch lens at the usual distance. Micro- 

 scopists have been accustomed to gain a lower power than could be 

 focussed by their rack, by screwing a low objective into the draw-tube 

 and focussing upon the object through the empty nose-piece. The new 

 plan of a reversible mounting is more convenient, and is applicable to 

 instruments that have no draw-tube ; unfortimately it cannot be used 

 with the ordinary binoculars. The lens, though of second class, was 

 very good. IVIr. Tolles has also arranged a 4-inch objective, in which 

 a short working focus is obtained by a reducing lens in the rear. 

 This reducing lens, for convenience, is moimted in a sliding tube, and 

 gives, when pushed in, a fair 3-inch power. As a 4-inch the combina- 

 tion is said to be extremely good. Mr. Bicknell appKes this expedient 

 to ordinary objectives ; placing in the draw-tube, instead of the concave 

 amplifier sometimes used, an achromatic convex lens as a reducer, with 

 which an extremely low power can be obtained with good definition, 

 flat field, and working focus not inconveniently long. A 4^ or 5 inch 

 lens (solar focus) may be used. A low objective of two combinations 

 may be divided, using one part as an objective, and placing the other 

 in the draw-tube. 



A Clinical Compressor and Microscope. — Dr. Ward had contrived a 

 " clinical " compressor for lase with the microscope of the same name. 

 The clinical microscope is very convenient for examining mounted 

 specimens. He had used it for years in teaching, but not much as a 

 " clinical." A glass slide to hold the object, with a thin cover held 

 on by capillary attraction, is well for once, but does not satisfy a busy 

 man. It applies to too limited a range of objects ; and the cover is 

 inconvenient to carry, awkward to handle, and easy to break. He had 

 used Wenham's compressor until lately, but that is inconvenient under 

 the springs of the " clinical " stage. The new compressor is simple 

 (and therefore inexpensive) and can be used with great facility both 

 for clinical and class use, and for much of the ordinary work of the 

 microscopist. It is reversible, except upon a large stage, in which 



