June 24, 1922] 



NATURE 



APPARATUS FOR CONTROLLING 

 THE ANNEALING OF GLASSWARE 



(Patents applied for) 



The Twyman Annealing Indicator 

 The Twyman Annealing Recorder 

 The Hilger Strain-Viewer :: :: 



The Annealing Indicator shows the progress of annealing within the Ichr or kiln during the actual process ; 

 enables perfect annealing to be obtained without the aid of pyrometers ; and indicates when annealing 

 is finished. 



The Annealing Recorder gives prompt evidence of the degree and uniformity of the annealing actually 

 effected. Furthermore, it enables the effective differences of temperature throughout the lehr or kiln to be 

 obtained in an extremely convenient way with a minimum of trouble and expense, and without in any way 

 interfering with the continuous use of the lehr. 



The Hilger Strain- Viewer is a final guarantee and witness of a well annealed article. 



DELIVERY FROM STOCK 



Descriptive booklet and prices post free on application to the Makers : 



ADAM HILGER Ltd., 

 75a Camden Road, London, N.W.I. 



Telephone Numbers : NORTH 1677- 



Telegraphic Address : "SPHERICITY, PHONE, LONDON.' 



ROSS 



Stereo-Prism 



BINOCULARS 



and 



NATURE 



Proved by the British Government, after 

 exhaustive tests, to be the best in the world, 

 they eliminate distance and will enable 

 you to observe wild bird and animal life 

 from a safe distance yet showing details of 

 marking and action as though you were 

 by their side. 



No other glasses give such perfect illumina' 

 tion and definition or wide angle of view. 



Ohtniuahle 0/ alt high-class dealers, or 

 at our West End Showroom , i^lnGreat 

 Castle St., Oxford Circus, London, IV.i. 

 Illustrated and descriptive booklet 

 pest free on request. 



ROSS 



CLAPHAH COMMON. 

 LONDON SW,4 



NEW 

 PARABOLOID CONDENSER 



This Condenser permits a convenient, rapid and 

 continuous transition from bright field to dark 

 field illumination and vice versa. Furthermore 

 it can be used with slides of varying thicknesses. 



Price £8:8:0 



Descriptive pampfilet on application. 



DELIVERY FROM STOCK 



DISTKlllUTOKS 



MM J. W. ATHA 81 CO. ^ 



v ="''^' --^ 8 Southampton Row, London, W.C.I. V:2i^ 



