December 30, 1922] 



NA TURE 



SUPPORT BRITISH INDUSTRIES.— By doing this you not only help 

 your country, but in this case you buy the best in the cheapest market. 



OIL IMM. 



12 



OBJECTIVE 



N.A. 1.30, complete in brass casp, 



£E& £5 . 5 . O 1S2S2Z 



£-IN., OF SAME MODEL - *2 . o . 



'12 O.I. by Swift, Beck, Watson, or Leitz, £550 

 or Watson, £1 15 



ift. Bake 



BROADHURST, CLARKSON & CO 



MANUFACTURING OPTICIANS. MAKERS OF MICRO- 

 SCOPICAL AND ASTRONOMICAL LENSES, 



63 Farringdon Road, London, E.C.I 



RADIUBV1 ON HBRE 



(Activity 1,800,000). 



RADIUM MICROSCOPES, 



Complete with Radium, 2,6 and 7/6 each. 

 These are SELF-LUMINOUS in the dark, 



showing splendid Scintillations. 



Pitchblende Scintilloscopes 



Extra Screens for Testing Minerals . 



7/6 each. 

 16 each. 



L 



F. HARRISON GLEW, 



6 Clapham Road, London, S.W.9. 



Telephones : 1787 Hop and 3117 Hop. 



G rainless Photography. 



Fllmless Photography. 



RHEIINBERG'S 



STAGE MICROMETERS AND EYEPIECE MICROMETERS 



New Stage Micrometer, 2 m/m in 200 parts, numbered. 



Chessboard Eyepiece Micrometers. 



From all Leading Optical Firms. 



RHEINBERQ & Co.. S7-60 Holborn Viaduct, London, E.C.l. 



ck list of s 



ndard article 



appli 



MARINE BIOLOGICAL ASSOCIATION 



OF THE UNITED KINGDOM. 



THE LABORATORY, PLYMOUTH. 



The following animals can always be supplied, either living- 

 or preserved by the best methods :— 



Sycon ; Clava, Obelia Sertularia ; Actinia, Tealia, Caryophyllia, Alcy- 

 onium; Hormiphora (preserved); Leptoplana ; Lineus, Amphiporus, 

 Nereis, Aphrodite, Arenicola, Lanice, Terebella ; Lepas, Balanus 

 Gammarus Ligia Mysis, Nebalia, Carclnus ; Patella, Buccinum, Eledone 

 Pectens Bugula Crista, Pedicellina, Holothuria, Asterias, Echinus 

 Salpa (preserved), Scyllium, Raia, &c, &c. 



For prices and more detailed lists apply to 



Bio logical Laboratory, Plymouth. THE DIRECTOR 



'aysjgfcniied 



J. W. Mason ^ Managing Director. 



Incorporating the HIGH TENSION COMPANY. 

 DESIGNERS AND MANUFACTURERS OF 



TRANSFORMERS, 



INDUCTION COILS, 



VACUUM TUBES, etc. 



11 Torrington Place, 

 Gower Street, London, W.C.I. 



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