It is to be wished that the maker would devise some plan by which the admirable lenses sold with this instrument could be utilized for the pocket. Mr. C. Curties, of Baker & Co., High Holborn, has kindly done something in the matter, and has made for me a metal holder. I have found this convenient, but should be glad to see something further done in the same direction, so that instrument, lenses, and holder could be sold for £2. This ought to be within the range of practical optics. The spring collar advocated by my friend Mr. Wright seems better, and would certainly be cheaper. The lenses would only need to be dropped in. To use my pocket holder one must unscrew the metal collar from the lenses before screwing them into the metal plates which carry them (Fig. 4). It is, however, something to have made a beginning: it is a step in the right direction. [Illustration: FIG. 4.--Two Leitz Lenses in holder (open).] [Illustration: FIG. 5.--Two Leitz Lenses in holder (closed).] A serviceable dissecting microscope--not a toy, but an instrument with which real work may be done--can be made at a cost of a few shillings. Such a one has been made for me by a friend with a positive genius for such work. The body is fashioned out of a parcel-post box 7 in. long, 3½ in. in height, and the same in width. From the centre of the sliding top a piece is cut away, leaving ledges to take a 3 in. by 1 in. excavated slip for small dissections, or a mounted slide of a large object, such as a whole insect, for examination. A further portion is cut away on each side to take a small dissecting dish (Fig. 6). To admit the light, a hole is cut in the side of the box; and the mirror consists of a piece of silvered glass which was bought of a hawker in the street. This is placed in the box opposite the square hole, and sloped at an angle of 45°. The aid of a skilled mechanic was sought for a small rod carrying a thread, which works in a piece of brass bent at a right angle. This piece of brass is screwed on the box, just above the aperture by which light is admitted, and carries a pocket magnifier, similar to that shown at Fig. 1. [Illustration: FIG. 6.--Home-made Dissecting Microscope.] This modest little instrument generally stands on my work-table, and has provoked some remark and a little good-natured banter from friends who have seen it. Nevertheless, I should be sorry to part with it, for I have found it extremely serviceable in many ways. And more than one critic has had to confess that better results were obtained than one would expect from its appearance. The total cost out of pocket was, 3_d._ for the box, 3_s._ for the lens, and 1_d._ for the plate-glass, while the man who made the pillar and ear-piece would take no more than 6_d._ for his work. This brings the total to 3_s._ 10_d._ With a little ingenuity the pillar might be made to carry a collar, and so take a Steinheil lens. This would swell the total cost to about 11_s._