Sept. 1, 1S66.J 



HARDWICKE'S SCIENCE-GOSSIP. 



209 



s t shall be two inches long - , v w one inch long, u v 

 about three-quarters of an inch longer than the 

 wood is thick ; and a piece of metal of about the 

 size of c (fig. 205). 



In the centre of the piece of wood cut a neat per- 

 pendicular hole, half au inch square ; pass e through 

 the wood as figs. 204 and 206,so as to retain b exactly 

 on the hole, and so that v w may be at right angles 

 to the length of the wood ; bend over the ends, and 

 drive them below the surface, as iu figs. 204 and 207. 

 Next insert d in the upper surface of the wood, so 

 that s t may lie on the surface in the direction of its 

 length, and form a support for the cutting edge. 

 Screw a through b from beneath, drop c in from 

 above, and the machine is complete. To use it, rest 

 one end on a table at an angle of 45°, lay the flat 

 side of a sharp chisel, wide enough to rest on both 

 the wires, and having previously pressed the wood 

 to be cut into the hole, and dipped the chisel in cold 

 water, press it from you, and take off the sections in 

 the usual manner. 



Note that the chisel must be kept flat against the 

 guides, or they will be notched, and the operation 

 will fail. N. D. L. 



N.B. — The letters refer to the same part in all the 

 figures. 



[We think that our correspondent's machine would 

 be improved by having the hole cut round with a 

 centre-bit, instead of square, as he proposes. — Ed.] 



Cuticle of Eern — If the Harts-tongue (Scolo- 

 pendriuM vulgar e) be carefully examined when the 

 seeds are pretty well developed, it will be fouud 

 that the seeds are covered with a thin tissue. This 

 is called the indusium, and is, in fact, simply an 

 extension of the pure cuticle. This can be cut off 

 readily with a razor or sharp knife. It forms a long 

 narrow strip, and is easily mounted. — T/ios. BrUtain, 

 Fattotcfield. 



The Staniiopescope. — Although a firm believer 

 in a Coddington lens, if sufficiently cut down, I 

 considered the glowing description given of the 

 above small optical instrument in your last July 

 number warranted a trial. With this in view, I 

 wrote to Mr. Barkas, of Newcastle, for one of each 

 description. It is due to your readers, I think, to 

 describe the little apparatus before going into the 

 merits of its performance. 1st. The lens is of the 

 same construction as those used by Dagron, of 

 Paris, to cement his small micro-photographs upon, 

 consisting of a small square bar of glass, upon one 

 end of which is worked a convex surface. It is not 

 right to call it a Stanhope lens ; and I notice in the 

 August number of your paper that it is now de^ 

 scribed as a Stanoscope (imde derimtur?). 2nd. A 

 brass tube, into which slides the cap, holdiug the 

 lens. That in use by Mr. B. must be far better 

 corrected to be of any use than those furnished to 



me. The short coloured tin one has the bar of glass 

 full of striae, which give prismatic colours, and the 

 flat surface is short of the focus of the worked 

 convex lens by about the ^nd. of an inch. Again, 

 the one in brass is evidently much more carefully 

 got up ; but here the flat suiface is too far off 

 the lens, and, consequently, anything placed on 

 the plane surface is not in focus. I do not 

 wish to deteriorate the article ; but I think the 

 generality of microscopists will be disappointed 

 unless the instrument is more perfectly adjusted 

 than at present appears to be the case. One pur- 

 pose I fouud it useful for : — If a drop of fluid 

 containing diatoms, or the dust (if I may so call it) 

 off any moth or other similar object, be placed upon 

 the plane surface, and a Coddington be used to 

 look at the same, the Stanhopescope acting as a con- 

 denser, improves the performance of the Coddington 

 very much. Whether this hint is worth anything 

 or nothing, I must leave to others to determine. 

 As I said before, it is no wish of mine to speak 

 against the instrument ; but, at preseut, there is 

 room for great improvement. — John Bockett. 



Mounting in Balsam. — I hear and read so 

 much of the difficulties of mounting, especially in 

 Canada balsam, that I cannot withhold giving 

 my experience, hoping that it may prove of use to 

 some beginners. A few years ago, I first had a 

 small student's microscope, and wished to mount. A 

 friend gave me a few hints, and lent me a brass 

 balsam-table and turning-table ; I bought a small 

 spirit-lamp, and without any other apparatus, I 

 begau. Of course, I made mistakes : nothing 

 daunted, I tried again ; and when I went in despair 

 to that same friend (who had mounted for herself 

 with considerable success), and asked innumerable 

 questions, the answer I got was — " With brains : 

 use your common sense." Thus driven back upon 

 myself, I tried again ; and before three months had 

 elapsed, I laughed at the idea of the difficulties of 

 mounting being insurmountable. Since then, I have 

 a binocular microscope, and have devoted some 

 time to mounting both opaque and transparent 

 objects. But I still have no grand apparatus, such 

 as air-pumps, hot-water stands, &c. I just warm 

 my balsam, and with a bit of stick drop some on 

 the object, having previously warmed the slide on 

 the brass table ; with a needle, mounted on a bit of 

 stick, I pick out the larger bubbles. Then I put 

 the thin glass cover on ; not at all carefullj', as all 

 books so especially recommend : I simply take it 

 between my finger and thumb, and drop it on. I 

 then leave the objects for that day, to allow them 

 to harden a little ; and the next, place them before 

 the fire in a small tin oven I have for the purpose ; 

 but a tray does quite as well— I used one myself 

 till quite lately. Placing them thus on the fender 

 for a few hours daily, draws out the remaining 



