August 3, 1905 J 



NA TURE 



VOQEL'S 

 SPECTROGRAPH. 



Two prisms of dense flint-glass enclosed 

 in a strong brass case, to which the colli- 

 mator and the camera are attached ; 

 collimator of liin. aperture and i8in. focal 

 length, with adjustable slit with micrometer- 

 screw and dividing drum ; the camera is 

 furnished with an achromatic double 

 objective of 2in. aperture and agin, focal 

 length ; size of plate, 7;in. by 5m. 



Can he seen at my Showrooms 

 as below. 



DELIVERY FROM STOCK. 



PETER HEELE, 



115 HIGH HOLBORN, 



LONDON, W.C. 



Maker of Physical, Chemical, and 



other Instruments, and every kipd of 



Spectroscope and Polarimeters. 



GRAND PRIX, PARI5, 1900; ST. LOUIS. 1904. 

 Telegrams: 'ARCTITUDE, LONDON." 



The New Manifolding 

 Hammond Typewriter. 



A Hammond Typewriter will do anything any other 

 typewritff does— and do it better. "Beside, it has 

 twenty exclusive features, not one of which is possessed 

 by ant/ other writing machine. 



WHY is the Hammond the Best Machine for 

 Steno(;>'aphers ? 



BECA USE 



Perfect and Permanent 



Alignment, 

 Work in Sight, 

 Manifolding. 

 Speed. 

 Durability. 

 Noiselessness. 

 Interchangeable Type, 

 Light Elastic Touch, 

 Perfect Paper Feed, 

 Any Width Paper, 



are essential ''^'quisites, and the Hammond 

 possesses them all. 



On account of the TYPE being interchangeable, it is most 

 useful to SCIENTIFIC work. 



Call and test Machine or write for Catalogue, free on appli- 

 cation to : — 



The Hammond Typewriter Co., 



50 QUEEN VICTORIA ST., E.G. 

 Manchester Branch: 164 DEANSQATE, MANCHESTER. 



X-RAY, HIGH FREQUENCY, LIGHT BATHS, 

 ELECTRO-THERAPEUtTc APPARATUS 



Of the Highest-class London Workmanship and 'Maximum 

 Efficiency at the Minimum Price. 



COX'S INDUCriOX* COKIliS. 



10" Spark (as illustrated), £18 lOs. 



HARIKY' Mil. cox:, I^td., 



la ROSEBERY AVENUE, & 15-21 LAYSTALL ST., LONDON, E.C. 



Actual Manufacturers from the Raw Material. 



Contractors to the various Departments of H.M. Government and many of 



the principal Hospitals and Practitioners in the United Kingdom and 



Colonies. 



Full Illustrated Catalogue (with Instructions to Beginners) Post Free. 



