Fig. 1.—Hand Magnifier and Stand.
A very good form is shown at Fig. 1, which represents a hand magnifier, fitted with three lenses of different focus, generally 2 in., 1½ in., and 1 in. Examination of the catalogues of the principal London opticians shows that such a set of lenses may be bought for about 3s. In shape and construction there is sometimes a little variation; but the form figured is that most generally adopted, and is, on the whole, fairly convenient. It would, however, be an advantage if the hole by which the magnifier is mounted on the stand were drilled in the solid part of the handle. This would not only do away with the objection that the hole in the case permits dust to penetrate to the glasses, when carried in the pocket, but would give a longer reach, and thus obviate the necessity for moving the stand if the observer were examining a large object. The price of the stand figured is 2s. 6d.; and one with a short adjusting arm ought not to cost much more.
Any one with a mechanical turn may make a stand for himself, though it may be doubted whether this is quite worth while when these articles may be bought so cheaply. Nevertheless, there is great pleasure in making things for oneself; and a home-made stand will enable the observer to do quite as good work as one that came from the optician’s shop.
A bill-file weighted at the foot may be bought for a few pence, and adapted to the purpose. For the slider a large cork cleanly pierced will answer admirably. This should carry a piece of stout wire, bent at the end thus __
, to serve as a holder for the magnifier, which should have a hole in the handle, for the reasons stated above. The only difficulty will be the attachment of the wire to the cork. The Rev. J. G. Wood advocated winding the wire round the cork in a spiral; and this is a very good plan. An increase of steadiness is secured, if a larger cork, or small bung, be used, and the wire inserted in the side.
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 6s.; one of the same construction, for use in the dissecting microscope alone, may be had for 4s. 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 10s. up to £1, according to the maker. Those made by Leitz of Wetzlar cannot be surpassed; and they are sold in London at 10s. 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.
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 9s.; with blocks for supporting the hands, at 10s. It is a useful instrument for small objects.