iS 



HA RDW1 CKE ' S S CIENCE- G O SSI P. 



the country the cheerful hedgerow is supplanted by 

 unsightly walls which are frequently built in very 

 rough style out of the loose stones found on the land, 

 or from similar materials from a neighbouring quarry. 

 If in a few instances the walls are neatly put together, 

 and the joints mortared, in many cases no mortar is 

 employed, but the wall is dry-jointed ; whence the 

 Scotch term "dry-dyker," or one who builds stone 

 walls without mortar or cement. Here, in Cumber- 

 land, one may see miles of such dykes, both in the 

 open country and on the Fell-sides (as the people term 

 their hills) ; and as a rule they consist of stones of 

 various shapes, sizes, and qualities, piled one upon 

 the other with some amount of care if not of skill, and 

 surmounted by a coping or cap of mud and small 

 stones. Thus a mud-capped dyke is simply a rough 

 wall serving as a fence, hedge, or boundary, made 

 either with or without mortar, and kept together by 

 means of a cap of clay or earth which has been 

 kneaded, beaten, or made stiff and impervious to the 

 rain. 



We shall next have to examine this clay and these 

 boulders or "cobbles" a little more closely, and if 

 possible trace their history, and then examine the 

 various forms of life which are to be found located 

 there. 



Carlisle. 



SCIENCE-GOSSIP. 



Mr. J. B. Beckett, Secretary of the Great 

 Yarmouth Naturalists' Society, sends us a copy of a 

 list of " The Mollusca of the Great Yarmouth District." 

 This is the first list of the district which has been 

 compiled, and, as the species named have all been 

 found by Mr. Beckett himself, it does him great credit. 



A New method of preparing Fluorine has been 

 discovered by M. Moissan. A capital account of it 

 appeared in "Nature," December 5th. 



A " Gilbert Club" has been founded in honour 

 of Dr. Gilbert, of Colchester, the author of " De 

 Magnete." Sir \Vm. Thomson is President, and all 

 the leading electricians of the day are members. One 

 reason for the club's existence is to republish an 

 English translation of " De Magnete," after the style 

 of the 1600 folio edition. 



Manchester has resolved to put up a memorial 

 to the late Dr. J. P. Joule. It has been resolved to 

 erect a marble statue to the deceased, and a committee 

 has been appointed to carry out the object in view. 



PHOTOGRAPHY. 



The following good hint for utilising old or spoiled 

 negatives appears in a recent number of " Work " : — 

 Old negatives may very easily be turned into printing 

 frames, or rather printing contrivances, for there is 



no frame needed ; but we will call them frames for 

 convenience. To make a printing frame for half- 

 plate photos, we only require two old quarter plates. 

 Cut a piece of strong black linen a little larger than 

 two quarter plates placed side by side, and paste 

 them down securely in that position to the linen ; 

 place this on a flat surface, and lay a heavy book, 

 etc., upon them until quite dry : then trim off the 

 linen to the exact size of the glass with a sharp knife. 

 Next procure four spring clips, as used for fastening 

 clothes on a line, and the printing frame is ready for 

 use. To make a print, place a piece of sensitized 

 paper of the required size upon the negative, and 

 then a piece of white blotting-paper, half-plate size, 

 upon the back of the print. Next lay the quarter 

 plates hinged with black linen, glass side down, upon 

 the blotting-paper, and secure with the four clips,. 

 placing two at each side of the frame, so that each 

 half of the;folding back shall be firmly held in position. 

 The print may be examined by removing the clips 

 from one end and raising the half, as in the case of 

 an ordinary printing frame. For carte-de-visite size, 

 a quarter plate cut into equal parts, and for printing 

 from whole-plate negatives, two half plates, backed 

 with linen as above, may be used ; for the larger 

 sizes eight clips will be required in order to ensure 

 perfect contact between the print and negative. 



A Photo-Microscope. — Mr. R. G. Mason draws 

 our attention to Leach's Improved Oxyhydrogen 

 lantern microscope, suited for microscopic projection, 

 for exhibiting the phenomena of polarized light upon 

 the screen, or for photo-micrography. 



Photo-etching. — We have much pleasure in. 

 drawing the attention of those of our readers in- 

 terested in the matter to a new method of photo- 

 graphy. Messrs. Sharp & Hitchenough, of 101 and 

 103, Dale Street, Liverpool, send us specimens of 

 their " Aptus " etching plates. The object of this 

 new invention is to provide a means by which artists, 

 especially ladies, may make etchings by a very 

 simple and inexpensive process. Acids are dispensed 

 with, as also the litho and copper plate press, more- 

 over the ease of manipulation is apparent when the 

 plate is etched upon, the image or drawing is not 

 seen reversed, as in copper-plate etching. By putting 

 the plate on a dark background, such as a piece of 

 black cloth, the lights and shades are seen as in the 

 print ; this necessarily makes the process of glr.ss- 

 etching much more simple, especially for amateurs. 

 In the box with the plates is supplied sensitized 

 photographic paper, which is known as sepia-type. 

 By the simple means of printing by light 'under the 

 etched glass negative in a pressure frame, the etching 

 is reproduced on the paper, after which nothing 

 further is necessary but to treat the print with several 

 changes of water into which a few drops of a 

 saturated solution of hyposulphite of soda is added. 



