SCIENCE-GOSSIP. 



9 1 



Black of the requisite size in the coil re rotating 

 the stage meanwhile by means of I he forefinger of 

 the lefl hand and the milled head beneath. As 

 soon as this black disk is dry, a piece of black 

 paper of the same size is cul oul and gummed upon 

 it. The black paper should no1 have a glazed 

 surface. Then upon the disk is built up a cell of 

 the requisite depth to contain the object. As we 

 have before said, however (Set ence-Goss] p, vol. vi. 



page '■'•''<), Ibis met bod of mounting opaque object s 



upon a black background is not only unnecessary, 

 Inn often inconvenient, as it renders the use of 

 transmitted light impossible, if it should be wanted; 

 neither can such slides be examined by means of 

 a Lieberkiihn. We recommend therefore that the 

 black background be omitted, and that instead a 

 similar disk, or two or three disks of various sizes, 

 be put upon thin slips, and one of these can then 

 be placed beneath the slide carrying the object, 



when it is bein.tr examined by reflected light. 



The cells arc made by running a ring of gold- 

 size of the same diameter as the cover-glass that. 

 will be \isr<\. This is done by means of the turn- 

 table, and is not difficult. It is not advisable to 

 use tun full a brush, and the gold-size should be of 

 the right consistency — neither too thick to leave 

 the brush, nor so thin as to run away from position. 

 The tip of the brush is used, and the table rotated 

 not too quickly. For very thin objects one ring 

 will Mirtice; but thicker objects will need two or 

 three rings, added one on the top of another, each 

 ring being added, however, only when the other 

 is dry. If a few such rings do not give sufficient 

 depth, it is advisable to build up the cell by other 

 means. Rings may be cut out of stout paper or 

 thin and good cardboard, then steeped in paraffin 

 and dried. Stout rings of ebonite, glass, tin, etc., 

 can be obtained from the opticians. It is only neces- 

 sary to attach these to the slide by means of a ring 

 of g< 'Id-size. ] iressing down the ring firmly, and even 

 giving a very slight twisting motion to make sure 

 of there being no air -bubbles to prevent perfect 

 contact. If the cells of gold-size when dry should 

 not be quite level, they can easily be rubbed down 

 on a piece of very fine emery laid on a flat surface. 

 The object itself must be fastened in place by 

 means of a drop of gum placed upon the slide 

 Care must be taken that this drop of gum is hidden 

 by the object, unless that is impossible. Thin 

 objects, such as wings, petals, leaves, etc., may 

 generally be kept in place merely by the pressure 

 of the cover-glass. Very minute objects, such as 

 pollen grains for instance, are made to adhere by 

 means of a thin film of very weak gum, which is 

 placed on the slide and allowed to dry. Breathing 

 upon the slide will then moisten the film of gum 

 sufficiently to cause the pollen to adhere when 

 placed thereon. In every case, however, it is of 

 the utmost importance that the gum and gold-size 

 should be allowed to dry thoroughly before the 

 cover-class is put on, or the remaining moisture 

 will settle on the under side of the cover-glass, and 

 utterly spoil the slide. A final ring of gold-size is 

 then run on, and this last should be allowed to dry 

 until it. is just sticky only, when the cover-glass 

 may be gently lowered into place by means of a 

 pair of forceps, and the edges pressed gently down. 

 care being taken that the cover-class adheres all 

 round its edges. Finally, the slide is finished by a 

 coal of Brunswick Black over all, and just covering 

 the edge of the cover-glass. 



(To be continued.') 



A New Minor Planet was discovered photo- 

 graphically at Heidelberg on June -1th by Professor 

 .Max Wolf and Herr Schwassman. 



The transactions of the "British Myoological 

 Society " for last year's season are of exceptional 

 interest, and graced by a coloured plate. There 

 are several papers, and the Presidential address by 

 Dr. 0. B. Plowright, also a list of fungi new to 

 Britain by Annie Lorrain Smith. 



PROFESSOR Chandler, of New York, was for- 

 mally admitted to the Chemical Society on July 

 5th. When he was welcomed by Prof essor Thorpe, 

 he caused much laughter by remarking that he 

 could only now consider himself a real member, 

 although he had been a " life " member for over 

 thirty years. On July 7th the University of Oxford 

 conferred upon him the honorary degree of Doctor 

 of Science. 



We would draw the attention of photographers 

 to Messrs. Cadett & Neall's plates and printing 

 paper. They will be found admirable, especially 

 the paper for X-ray work. We are reminded ot 

 this by the reference to the Cadett light filters in 

 Mr. Sanger Shepherd's article on the " Photography 

 of Colour" in this number. The firm will supply 

 particulars on application to their works at Ash- 

 tead. Surrey. 



An interesting paper on abnormalities in the 

 shell of Helix nemoralis appears in the July 

 number of " The Irish Naturalist." It is accom- 

 panied by a beautiful group, illustrating nineteen 

 examples, from a photograph by the author. Mr. R. 

 Welch, of Belfast. On the same page is also a fine 

 photograph by the same gentleman of a cluster of 

 ova of the Kerry slug, Geomalacus maculosus. This 

 latter illustration is accompanied by some inter- 

 esting notes from the pen of Mr. Thomas Rogers. 



It is satisfactory to find practical applications 

 of the various systems of wireless telegraphy are 

 still being energetically made. It is reported that, 

 in consequence of the successful experiments made 

 with M. Popoff 's system, the Russian Naval Minister 

 has decided to introduce it into the navy. The 

 whole of the Black Sea fleet will, it is said, be 

 fitted up this summer with the necessary apparatus. 

 Both in our own navy and in that of Germany the 

 question of signalling in this manner is receiving 

 considerable attention. Experiments were success- 

 fully carried out a week or two since between the 

 battleships Jupiter and Hannibal. Messages were 

 distinctly read when the ships were twenty miles 

 apart, and occasionally when at thirty miles' di-- 

 tance. In Germany an apparatus, with a wire 

 205 feet high, has been put up for the North 

 German Lloyd at Kaiserhaf en to effect communica- 

 tion between lighthouses and fireships. The large 

 Lloyd steamers are gradually all to be equipped 

 with apparatus worked upon what is termed the 



Schafer system. 



