Journal of the Royal Microscopical Society
A. Instruments: Accessories, etc.* (1) Stands. Winkel's Stand No. 1.t-This stand (fig. 31) has been specially designed for photomicrographic work and visual observations demanding the greatest precision. It has rack-and-pinion, coarse-and new form of fine-adjustment, one division of the drum of which represents a vertical movement of 0.00," mm., centring rotating mechanical stage, the lateral mechanism of which can be removed ; the rotation can also be clamped by means of a milled head ou the
... ft-hand side of the instrument ; irisdiaphragm mounted beneath the stage; substage illuminator No. 1, body-tube 6 cm. in diameter, thus permitting the use of the lowpower micro-luminars without cutting down the field, after removing the draw-tube, which is of the usual standard gauge graduated to millimetres. The whole is mounted on a heavy horseshoe foot with hinged upright-hand clamp ; the instrument can thus be set at any convenient inclination from vertical to horizontal ; the fitting carrying the plane and concave mirror can be removed when the instrument is required for use in the latter position. Winkel's Travelling Microscope.$-This instrument ( fig. 3 2 ) which is of medium size, can, by hinging stage and foot, be fitted into a case 11& x 8 x @ in., thus rendering it much =ore portable than our laboratory models of similar size. I t has rack-and-pinion, coarse-and micronieter screw fine-adjustrnent, square stage fitted with iris-diaphragm, substage illuminating apparatus, with screw focusing adjustment, graduated draw-tube, double nose-piece, and joint for inclination. The method of packing will be obvious from the illustration. Before rotatihg the stage to pack the instrument, the mirror, which slides in a groove, must be losered, and on again setting up the instrument care must be taken to see that the stage is brought right over to the stop * This subdivision contains (1) Stands; (2) Eye-pieces and Objectives: (3) Illuminating and other Apparatus ; (4) Photomicrography ; (5) Microscopical Optics and Manipulation; (6) Miscellaneous. t R. Winkel, Gottingen Catalogue, 1911, pp. 28-3 (1 fig.). : Tom. cit., p. 45 (1 fig.). ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 249 FIG. 31 provided, thus assuming a truly horizontal position before clamping, otherwise the optic axis will not be perpendicular to it. Fro. 3?. ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 261 Winkel's Dissecting Microscope.*-This instrument ( fig. 33) gives greater working surface than most dissecting Microscopes. As will be seen from the illustration, it has rack-and-pinion focusing adjustment and also a rack-and-pinion movement for adjusting the optical system in a horizontal plane, which, together with a rotary movement i n the FIG. 33. same plane, pekmits of its use over any desired portion of the stage. The arm carrying the optical system is slotted to receive either the Porro erector, which can be used with ordinary objectives and eyepieces, or a ring to carry single lenses, both of which are provided, together with silvered and opal reflectors for illuminating transparent objects, and a plate with black and white surfaces-shown in the illustration swung aside-as a contrast background for opaque objects. SUhlMAXY OF CURRENT RESEARCHES RELATIXG TO (2) Eye-pieces and Objectives. Edinger's Pointer-Double-Ocular.*-In spite of the advantages of the pointer-ocular, L. Edinger has long felt that an eye-piece which would allow of simultaneous observation by two persons, and which would at the mme time preserve the principle of the pointer, was a great desideratum. The applicability of such an auxiliary to teaching purposes needs no demonstration. The apparatus shown in fig. 34 has been made by the Leitz firm to the designs of C. Metz, and is found to answer its purpose completely. The name Pointer-double-ocular (Zeigerdoppelocular) has been given to it. Between the collective-lens and the eyelens of an ordinary ocular and exactly over the ocular diaphragm a double prism, i. ii., is inserted. Prism i. is an isosceles prism of angles 35', 3 5 O , 1104 Prism ii. is right-angled, with angles 35O, 55" and 90". The prisms are placed so that their larger sides (i.e. those opposite llOo and 90") are in juxtaposition, and in such a manner that they are separated by an exceedingly thin layer of air. At this air-space, inclined at 55" to the optic axis, a partial reflexion of the light-beam takes place. FIG. 34. About two-thirds of the beam passes on and about one-third is reflected. The image formed in the main optic axis is therefore somewhat brighter than that formed by reflexion. The images formed are of equal value, because in both the full aperture of the objective is utilized. The axis of the reflected image forms with the axis of the Microficope an angle of 70'. Lateral observation would be quite possible if an eye-lens, the same as for the vertical observation, were applied at a suitable distance. But this would bring the lateral observer too near to the tube and to the first observer. Therefore a lens combination is applied somewhat similar to a terrestrial ocular. The tube of this telescope has a downwards inclination which imparts some difficulty to its use until the observer's head has found the right position. But the Leitz firm also deliver the apparatus with an upwards-inclined tube, and for this purpose prism iii. is introduced. This, however, has the effect of weakening the light, and the author prefers the first method. Adjustment is made at the vertical eye-lens, and this is simultaneously effected through the bent tube at the second eye-lens. If the second observer's eyes are not normal * Zeitschr. wise. Mikrosk., xxvii. (19lO)-pp. 3368 (1 fig.) .' ZOOLOGY AND BOrAKY, MICROSCOPY, ETC. 253 he must correct them by spectacles. The two images are then identical and the pointer appears in each. The slight difference in brightness is not found to be a detriment. The author has, after a year's experience, found the instrument a very valuable help in his demonstrations. BOEOEHOLD, H.-Eine neue Konstrnktion von Korrektionalinsen. [Chiefly relates to telescopes ] Zeit. f. Instrumntenkunde, xxx. (1910) pp. 302-7 (1 fig.) . (3) Illuminating and other Apparatus. New Method for Microscopical Metallography.*-E. Sommerfeldt describes J. Konigsberger's apparatus and method. If natural light be allowed to fall by means of a vertical illuminator on an isotropic surface the reflected light does not exhibit polarization. 3 u t if the reflexion occurs at an anisotropic surface a separation of the light takes place into two components vibrating perpendicularly to each other, and these components are of unequal intensity, so that a partial polarization follows. Two arrangements serve forrealizing this polarizing effect on well-polished surfaces. The simpler arrangement-not serviceable, however, for quantitative measurements-consists of a Klein quartz plate, in combination with a nicol prism (polarizer), placed in front of the vertical illuminator ; the analyser (inner nicol) remaining in the nsual place. The Klein plate gives violet effects with isotropic substances ; but with anisotropic substances it l u mishes a coloured field which changes during rotation (red and blue ; with strong anisotropy, bright yelluw or green). The second arrangement involves the use of a Savart's double plate, which, observed with a telescope adjusted foi infinity, must reveal between crossed nicols two deep black quite sharp bands, surrounded by coloured bands. If unpolarized light is reflected (i.e. if the preparation is isotropic) no bands appear. The more complete the polarization of the reflected light the clearer appear the bands, and therefore the deeper the anisotropy of the preparation. By means of a contrast plate, prepared out of two smoke-quartz 'plates cut perpendicularly to the ans, the bands become intensified. The preparation must be very accurately set perpendicular to the incident light rays, and this is effected by the adjusting apparatus J seen in fig. 35 . Application of Mercury Light to Microscopical Works.t-A. Rohler describes a Hageh Microscope lamp which the Zeiss firm have made for him and which he has found very useful in his microscopical work. The light source is furnished by one of Messrs. Schott's Hageh lamps, in which the mercury column has a special length of 20 cm. A special S 254 SUMhlARY OF CURREST RESEARCHES RELATING TO resistance coil is supplied for use with currents of 65 to 220 volts A current strength of about 3 . 5 amperes is necessary. As seen in fig. 36 , the tube is placed in an inclined position in a I -s h a p e d holder and secured with springs. The lower end of the lamp where t h e mercury accumulates is connected with the negative pole of the circuit. The lamp is shielded from the observer by an iron shade, so as to shut off the superfluous light : the shade has an opening opposite the middle of the lamp for transmitting the light, which then impinges upon the flask filled with a solution and acting as an engraver's globe. The holder of this flask (see figure) also acts as a handle for lifting the whole apparatus. The effect of the entire arrangement is to throw an image of the illuminating mercury column on the iris diaphragm of the Microscope, and hencc 011 to tlie plane of the object. The fluid in the flask not only FIG. 36. provides light for the lenses but also acts as a light filter. For clear green light of wave-length 546 pp (this is the brightest line of the mercury vapour lamp) the filter should have the following composition :distilled water, 300 C.CIII. ; picric acid, 0.4 grm. ; copper sulphate, 3.5 grm. ; didglnium nitrate, 15.0 grm. If this didymium nitrate be omitted no light is transmitted beyond the line X = 516 p p ; t h e yellow lines X = 576 pp and 559 pp also disappear. These two yellow lines are, hoxever, obtained with great brightness mith the following solution :-distilled rater, 300 c.cm. ; potassium bichromate, 15 grm. ; copper sulphate, 3.5 grm. ; sulphuric acid, 1 c.cm. The blue and violet lines X = 436 pp, 407 pp and 405 pp are obtained with :-distilled water, 225 c.cm. ; copper sulphate, 1 grm. ; ammonium hydrate, 55 c.cm. With subjective observation only the line 436 pp is effective, as it is much more intensive than the two violet lines ; the light in this case is, therefore, practically monochromatic. Flasks can be filled with the respective solutions and secured with well paraffined corks ; they are then always available for obtaining light of their corresponding colour's. For the ZOOLOGY AND BOTANY, MICROSCOPY, ETC.