with the pillar support, so that when the Microscope is required to be used much inclined the horse-shoe base can be turned round as shown in the fig. This increases the stability of the Microscope, and adds so little to the original cost that the makers of these inexpensive forms may profitably adopt the suggestion.

Mr. McLaren also uses a system of fine adjustment applied at the nose-piece (shown in the fig.), consisting of a ring fitting in the lower end of the body-tube, in which the nose-piece proper, carrying the objective, is screwed by means of a very fine screw, 200 threads to the inch. The focusing is effected by turning the nose-piece either way, by which the objective is raised or depressed very slowly owing to the fine pitch of the screw. By this system, which is also applied to some old forms in our possession, the objective is made to rotate with every movement of focusing, which cannot be commended.

Schieck's Revolver School and Drawing-room Microscope. Winter's and Harris's Revolver Microscopes.-F. W. Schieck has just issued the Microscope shown in fig. 10 A and B, intended for school and drawing-room demonstration. The peculiarities of the instrument are fully set forth by Herr Schieck himself in the following statement (translated), which also includes some very original directions for preparing objects:

"The management of a Microscope of the ordinary construction, with fixed stage, movable tube, different eye-pieces, objectives, &c., offers, in most cases, so many kinds of difficulties to the lay public, especially to young students, in the inspection of the preparations accompanying the Microscope, and in the adjustment of the image, but especially in the self-preparation of objects, that this important and interesting instrument has not yet attained that position either among our intelligent youth, or in our drawing-rooms, as an object of instructive entertainment, which befits its high ethical importance. The management of the Microscope has even been found so intricate, that in consequence (as I have had the opportunity of seeing on numberless occasions) it has been very soon put aside again, after a short trial.

My new Microscope entirely removes this disadvantage. of such simple construction, and its management so thoroughly easy, that any one, even without any previous acquaintance with the use of a Microscope, is able to observe with it, as well as to make for himself beautiful microscopical preparations.

The new Revolver Microscope has, instead of a stage, a vertical drum, turning on its axis (like the chambers of a revolver), in which twenty different very beautiful and instructive preparations, from the three natural kingdoms, are arranged, which, on turning the drum, are brought successively into the field of view of the Microscope. The movable mirror is in the centre of the drum, and is easily and conveniently adjusted.

The Microscope is provided with a hinge for inclining the stand, so as to be able to observe conveniently whilst sitting.

The twenty preparations are numbered, and an explanation of them accompanies each Microscope.

As the Microscope has only one objective, and one eye-piece, and therefore only admits of a fixed magnifying power, a special focusing arrangement is not necessary. The tube of the Microscope is so fixed, that the image of the preparation is always in the field of view of the eye-piece, and only in the case of differences in the eyes of observers is a small shifting of the tube, amounting to a few millimetres, requisite. For this purpose the body-tube is easily pushed with the hand up or down, guided by a pin working in the

small slit in its sheath, without ever thereby losing sight of the image of the preparation, as happens with other Microscopes.

The magnifying power is such that most popular objects can be seen distinctly and perfectly. The images are of unsurpassed sharpness and clearness.

The field of view is very large, and all preparations which are not more than 4 mm. in diameter can be seen entire at one view. An entirely special advantage of this new Microscope is the uncommonly simple manner in which the teacher or student is enabled Ser. 2.-VOL. IV.

I

by its means to prepare by himself a new series of twenty preparations at pleasure. The hitherto general practice of laying the object to be inspected on large glass slides, and fastening over them the thin, round or square, cover-glasses, presented so many difficulties that a preparation seldom succeeded well, especially if it were put up for any length of time.

With each of my new revolver Microscopes is given a second stagedrum, with twenty empty apertures, and a sufficient number of small round glasses and spring-rings for firmly fixing the preparations. The stage-drum with the preparations already attached to the Microscope is unscrewed from the milled disk, and the second empty drum put in its place.

The insertion of a new object is so exceedingly simple, that directions for it seem, properly speaking, superfluous. In the first place a small round glass is washed clean, and with the forceps belonging to the Microscope, is laid in one of the apertures, then the object to be examined is laid in the middle of this glass, either dry or with mounting liquid (glycerine, gelatine, Canada balsam, or in cases where only a rapid observation of an object is required, even water, spirit, &c.), and covered with a second previously cleaned glass, fastened down with a spring-ring which goes into a small groove made for it, and the preparation is ready. () It must, however, be here observed that all hard objects (especially insects) must, in order to succeed well, be previously heated for a few seconds in a small reagent glass, with caustic potash over a spirit flame, by which means the preparations become soft and quite transparent.

The preparations are perfectly protected from dust by a pasteboard cover, and care must be taken always to replace the cover over the stage-drum, after using the Microscope. If, in spite of this, dust should after a time fall upon the preparations, it must be carefully brushed away from both sides by the soft hair brush accompanying each Microscope; any other cleaning of the preparations is never necessary.

If desired these Microscopes can be supplied with special objects previously given me to prepare, and for the requirements of schools the stage-drum can be fitted with botanical, zoological, or mineralogical preparations. Price according to agreement.

This entirely new, and in every respect original and practical Microscope offers to every one such a fund of entertaining and instructive matter, and will prove to the teacher as well as the student such an inexhaustible source of suggestive occupation, by which to pass the leisure hours usefully and pleasantly, that there is scarcely anything better fitted for a present, always gladly seen, especially by the ripening student. The price is fixed as low as possible, and considering the prices ruling here may be called very cheap."

Herr Schieck intended, we have no doubt, to be strictly accurate when he announced his instrument as "entirely new " (ganz neu) and "in every respect original." But it was in fact anticipated by two now in Mr. Crisp's collection, which were made more than fifty years ago, by T. Winter (simple) and Harris and Son (compound, fig. 11).

They are in principle identical with that of Schieck. The revolving object-holder is, however, made of ivory, and is much larger, being 4 in. in diameter and 1 in. wide. There is also a double row of apertures for the objects-one row for transparent, and the other for

There is also

opaque so that, instead of 20, it holds 44 objects. at one point of the circumference an intermediate set of apertures, apparently for inserting further objects on disks, corks, &c. (In Winter's there is a complete row of 19 of these apertures, 10 with corks).

Winkel's Large Drawing Apparatus.*- This (fig. 12) is intended for drawing objects under a low power, and also without any magnification. On the side of the standard A, and above the stage T and mirror S, is a cross-arm B carrying a lens L, and over it a small right-angled prism P, which acts as a camera.† On the other side there is a longer arm, also with a prism for drawing objects in

*Dippel's 'Das Mikroskop,' 1882, pp. 632-3 (1 fig.).

The text states P to be a prism (protected by a ring) though the fig. hardly agrees.

natural size. The arms can be raised and lowered by the sliding within A of the support to which they are attached, the screw on the right clamping it.

Jung's New Drawing Apparatus (Embryograph) for Low Powers.-H. Jung was induced, by the inconvenient or ineffective performance of other drawing apparatus, to construct a new one (fig. 13) in accordance with the friendly advice of Professor v. Koch, giving powers of about 1 to 20 or 4 to 30 in continuous succession.

Upon the heavy square iron foot rests (besides the column and the bar P, movable by rack and pinion) a concave mirror to illuminate transparent objects. The latter is 80 mm. in diameter, and consists of a plano-convex lens silvered at the back. It is supported on a hinge-joint, which is attached to a short rod fitting into a springtube h, and this is screwed to a carrier T having a longitudinal slot. The carrier rests on the foot to insure greater stability, and on loosening the screw S which clamps it, it can be moved so as to obtain any desired position of the mirror, either by turning it round the screw as a pivot, or by sliding it along the slot.

Upon the column is a stage 75 mm. deep, and 108 mm. wide. The stage, instead of a round aperture in the centre has a horseshoe

Zeitschr. f. Instrumentenk., iii. (1883) pp. 165-7 (2 figs.).