HARDWICKE'S SCIENCE- GO SSIP. 



65 



MICROSCOPY. 



American Microscopy.— At the annual meeting 

 of the American Microscopical Society of the city 

 of New York, held Tuesday evening, January 25th, 

 1376, the following officers were elected for the 

 ensuing year :— President, John B. Rich, M.D. ; 

 Vice-President, Wm. H. Atkinson, M.D. ; Secre- 

 tary, C. F. Cox ; Treasurer, T. d'Oremieulx ; Cura- 

 tor, 0. G. Mason. 



A Simple Section-machine.— Those who work 

 with the microscope well know the advantage of 

 possessing some kind of machine for cutting thin 

 sections of various substances, and in order to aid 

 those whose purses are not overstocked, I send 

 drawing (half-size) and description of a simple little 

 instrument, which can be constructed by any one 

 possessing the tools and a little mechanical ability, 



rience of thirty years, and having prepared in that 

 period some thousands of slides.— S.L. B. 



"Water-glass." — Can any of the readers of 

 Science-Gossip give me their experience in the use 

 of silicate of soda—" water-glass," as it is some- 

 times called— as a medium for the mounting of 

 algse, desmids, &c ? What is the mode of pro- 

 cedure, and where can it be obtained ? I have tried 

 at the chemists' without success. — St. T. H. 



Fig. 32. Simple Section-cutting: Machine. 



or, where time is an object, purchased for a small 

 sum (see advertisement). By referring to the 

 sketch, it will be seen that the principle of action is 

 a very ordinary one, the form only being reduced 

 to the simplest possible. It consists of a slip of 

 mahogany, a, faced with a stout plate of brass 

 made perfectly flat. Previously to fixing this plate, a 

 hole about 5 in. must be bored exactly in the centre 

 of the wood, and extending to within about t in. 

 from the opposite end; this done, the plate may be 

 fastened on, and when all the edges are filled quite 

 flush with the wood it will present a very neat and 

 finished appearance. The milled-headed screw, b, 

 works against a piston sliding in the interior, and 

 that at c steadies and compresses the sheet while 

 being cut ; both work in thick slips of brass let into 

 the wood and securely fastened. I have cut some 

 very beautiful sections with this instrument, and 

 have never come across anything of the kind so 

 efficient and yet so easy of construction.— J. H. 

 Barton. 



Gold-size.— I would ask "J.R. T.," if succes- 

 sive layers of gold-size ever do dry, or at least, if 

 the last applied coat does not soften again those 

 beneath ? I have had slides remaining perfectly 

 sound for many years, but then, from some cause, 

 the fluid has evaporated, and the gold-size has taken 

 its place. I venture to suggest this after an expe- 



Cement for Glycerine Mounting. — Having 

 received several inquiries respecting this cement, 

 I subjoin the following directions for its preparation 

 and use :— White lead in powder, red ditto in ditto, 

 litharge in ditto, — equal parts of each. These 

 are ground together with a little turpentine until 

 thoroughly incorporated, then mix with gold-size. 

 The mixture should be sufficiently thin to work 

 with the brush ; it is perhaps scarcely necessary to 

 say that the edge of cover and slide should be free 

 from moisture before applying the cement, and the 

 first coat allowed to dry before putting on a second. 

 The last can be applied somewhat thickly, or, as 

 the japanners say, floated on. No more of the 

 cement should be made than is required for present 

 use, as it soon sets and becomes unworkable. To 

 save the trouble of grinding, a stock of the mixture 

 can be kept ready ground in a bottle.— F. K. 



ZOOLOGY. 



Abundance of Sphinx Convolvuli— There was 

 quite a commotion in entomological circles caused 

 by the appearance of this grand hawk-moth all over 

 the country in the autumn of 1875, and of course 

 there are plenty of theories afloat to account for 

 this phenomenon. Against the theory that the 

 moths have travelled here from the Continent, we 

 must set the fact that many specimens have turned 

 up far inland, and also that larvae and pupae were 

 taken in some places ere the moths were captured. 

 One of the most extraordinary circumstances in 

 the history of the species is the occurrence of so 

 large a preponderance of barren females amongst 

 the September specimens, nor does it appear that 

 any eggs are deposited in the autumn. Where, 

 then, do the moths live during the winter ? Or, do 

 a small number of foreigners make their way across 

 to us in the spring of certain years, and lay eggs in 

 Britain, from which are produced these singular 

 autumn flights? But then it is odd that none are 

 netted, or even seen in the spring by some one 

 or other of our hundreds of entomologists. Very 

 probably, we frequently fail to detect the larva 

 owing to its habit of concealing itself by day, 

 actually retiring, as it is said, below the surface of 

 the earth ; and though there are entomologists who 



