The Optical Magic Lantern Journal (December 1890)

x x 6 tin a little, and so that when screwed down it will hold the circle of wood (B) at any angle required. Now place a }-plate or 1-plate carrier on the piece of wood (B) ; nail it down tight, and saw out the wood so that ! the negative used gets all exposed, and you havea: carrier for your negative that is a luxury, aS you can place your negative at any angle and clamp it there. This carrier can be made altogether in wood, if desired; but I have given the instructions for making it at the minimum of expense. The enlarging stand, as explained, with the front, is now on the market—by the Fry Manufacturing Company—and is sold as “ The Dresser Enlarging and Reducing Apparatus.” If you refer back to Fig. 2, the camera which I use for enlarging, you will see it is for enlarging up to § x 10 only ; but by taking out the ground glass back (H) I can place the front of an extending camera in it and enlarge up to 15x12. -Fig. 3 shows the camera with extension on it, as used for enlarging up to this size ; the length of focus of this camera is 6ft. 6in., and I can enlarge a }-plate up to 15 x 12, when using a Beck R.R. for 8x 10 camera. The drawings will, however, explain what I mean. I have just had the camera and stand made to my drawings, and the cost of allwas £11 or £12; and anyone who wants to go in extensively for enlarging cannot do better than indulge in one, if he can find time to work by daylight ; but I do not recommend it for artificial light. (To be continucd.) The Photography of Microscopic Objects.: By W. Low SARJEANT. I FERL sure that many microscopists are deterred from practising photo-micrography because they think there is so much difficulty about it, and so there pro The Optical Magic Lantern Journal and Photographic Enlarger. of division, and consequently better able to render minute detail), one or two developing dishes, and a ruby lantern, in addition to the microscope—which of course every microscopist has —is all that is needed. The microscope in use is to be placed horizontally, and is therefore in the same position as if the camera lucida were being used, the mirror being removed or turned aside, as it will not be required. The lamp— which is the ordinary small micro-lamp—must be placed with the wick turned edgeways, and care must be taken that the flame is exactly in the optical axis of the microscope. I find that if a small piece of camphor, say about the size of a hazel nut, is putin the lamp ; with the paraffin, in which it readily dissolves, it will most decidedly increase the whiteness and luminosity of the flame. The bull’s-eye condenser inust be placed between the lamp and the microscope in such a position as will best illuminate the field. Many workers remove the eye-piece from the microscope. I prefer to leave it in its normal position, for the following reasons :—First, because it enables a ! good magnification to be obtained with a camera of ordinary length; and secondly, because whilst . focussing the image on the ground glass I can reach | to arrange any special apparatus for so doing. all the adjustments of the microscope without having Iam aware that by the use of the eye-piece a certain amount | of light is lost, but that is of little consequence in using the low powers. For instance, with a 2-in. objective a fully exposed negative may be obtained in from ten to twenty seconds, the object being say a fairly transparent section of wood, an exposure which no one could object to on account of its length. The camera must be rigidly fixed, and placed so that the eye-piece of the microscope will pass through the centre of the hole in its front, in place of the ordinary photographic lens. Of course the junction between the microscope and camera must be made light-tight, but that is easily effected by wrapping a strip of velvet round the microscope tube until it fits in the camera front. It isadvisable that a rough base board be made for the camera, which should project in front far enough to enable the ‘microscope and lamp to stand upon it, as by this means the whole apparatus is made much more rigid, which is a very essential point, as the slightest vibration or shifting will spoil the plate. ; The focussing screen next claims our attention, and my method, which is a modification of Mr. J. B. Dancer’s, I will now describe. The ground-glass of the finest description is to be slightly warmed, and a piece of wax rubbed all over it. This will considerably increase the transparency and fineness of the grain’ Now draw two pencil lines diagonally across it on the ground side, and in the centre, where the lines bably is when working with high powers, and diatoms, | test objects, and such subjects are photographed; but if : the low or medium powers of the microscope are used, . ; taining a sharp image, but to make it still more cer the microscopist will find it very simple, and with very little practice will be able to obtain tolerably good negatives, from which it will be an easy matter to produce effective lantern slides The apparatus absolutely required is very little. An ordinary j-plate camera without a lens or stand, a few chemicals, a packet of dry plates (preferably a slow brand, as the silver bromide is in a much finer state cross, Cement a cover glass with Canada balsam. This entirely destroys the grain and produces a transparent circle. There ought to be now little difficulty in ob tain it is advisable to use a focussing glass. I use for this purpose a D eye-piece, with the eye-glass removed. and the cap made of such a length that when’ it is resting on the f/vz” side of the ground glass the pencil lines are sharply in focus. If now the focussing eye-piece is placed over the transparent centre of the screen, and the microscope adjusted until the object