There are, of course, more expensive lenses, with which better definition can be obtained. Zeiss has an excellent magnifier consisting of two lenses, for use in the dissecting microscope (Fig. 2), and also as a hand lens, at the price of 6_s._; one of the same construction, for use in the dissecting microscope alone, may be had for 4_s._ The Steinheil achromatic lenses are probably the best of all. These are made in powers ranging from 2 in. to ½ in. focus[2]; and the price varies from 10_s._ up to £1, according to the maker. Those made by Leitz of Wetzlar cannot be surpassed; and they are sold in London at 10_s._ each, either mounted in a handle, for use as hand magnifiers, or with a collar for use in Leitz’s dissecting microscope (Fig. 3). Mr. Lewis Wright says that ‘the best plan is to combine both uses, and have two or three powers in collars, with a spring ring folding into a handle, which will carry any one of them in that manner. A Steinheil lens at this low price costs little more than a Coddington, while its performance is infinitely superior[3].’ It is a difficult thing to get makers to deviate from the beaten track, and so far as I have been able to learn, Mr. Wright’s wishes have not been fulfilled. [Illustration: FIG. 2.--Zeiss’s Dissecting Microscope.] The lenses and stand (Fig. 1) constitute a simple form of dissecting microscope. If the worker wishes for something more elaborate, he need only consult the catalogues of the principal makers to find something that will meet his requirements. Zeiss’s brass stand, with stage, above which a lens slides up and down in a holder (Fig. 2), is sold for 9_s._; with blocks for supporting the hands, at 10_s._ It is a useful instrument for small objects. My favourite instrument is shown at Fig. 3. Here the focussing of the lens is effected by rack and pinion work, by means of the screws on each side the upright pillar. The lens is shown fitted in the collar which carries it. The stage is of glass--roughly, 2½ in. long by 2 in. wide, and the arm at the top of the pillar can be moved from side to side, so as to bring a fairly large object within range. The metal framework of the stage is furnished with nickelled clips (not shown), which serve to hold an excavated slip. The arm-rests are detachable, and the uprights are hinged for convenience of packing. The instrument (with the exception of these rests) packs into a neat, strong mahogany box, 7½ in. in length, and about 5 in. in height and width. With two powers--1 in. and ½ in. are very serviceable ones--the cost is 38_s._ [Illustration: FIG. 3.--Leitz’s Dissecting Microscope.]