July 27, 1905] 



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 iSin. focal 

 length, with adjustable slit with micrometer- 

 screw and dividing drum ; the camera is 

 furnished with an achromatic double 

 objective of 2in. aperture and 29in. focal 

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



Can be 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 kind of 



Spectroscope and Polarimeters. 



GRAND PRIX, PARIS, igoo; ST. LOUIS, 1904. 

 Telegrams: " ARCTITUDE, LONDON." 



MARCONI'S WIRELESS 

 TELEGRAPH COMPANY, 



i.Tr>. 

 Manufacturers of 



ELECTRICAL INSTRUMENTS 



of a// kinds for 



LABORATORY oS WORK, 



of the highest degree of efficiency 

 at moderate prices. 



BEWARE OF 



FEEBLE 

 IMITATIONS 



DO YOU WISH 

 TO BE 



UP TO DATE 



in Scientific Demonstrating ? 



fullde 



pampnlet of 

 the Kershaw.Patent Lantern 

 (Stioud and Kendall's and 

 Kershaw Patents), made of 

 best seasoned mahogany, 

 French polished, lined with 

 asbestos and Russian iron. 

 Fitted with two double 

 achromatic objectives, go" 

 silvered prism, complete 

 with B.T. or mixed jet, in 

 travelling case, measuring 

 ■ X 16" X 9". 



ALL ACCESSORIES SUPPLIED. ARC LAMPS, RESISTANCES, 

 STANDS. &c. 



mII'-Ik a. KERSHAW, Dorring-ton St., Leeds. 



co.vrKACTO/; to h.m: 



ll-EKXillEXT. 



ILLUSTRATED J'HICE LIST POST 

 FREE OX APPLICATION. 



London Office : 18 FINCH LANE, E.C. 

 Works: CHELMSFORD. 



ALSO AT 



BRUSSELS, PARIS, ROME. 



LABORATORIES FURNISHED 



Chemical, Physical, Biological, and all Science 



Laboratories completely equipped with Benches, 



Fume Chambers, Cupboards, &c., and Scientific 



Apparatus of every description. 



SEX It SPECIFICATION I'OK OVJl PHICES. 



We also supply Sinks, Gas and Water Fillings 



specially designed for Science Laboratories, and 



Pure Chemicals. 



A. GALLENKAMP & CO., LI^ 



19 & 21 Sun Street, Finsbury Square, LONDON, E.C. 



