October 19, 1 903 | 



N. I TURE 



VOGEL'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 ?X)m. focal 

 length ; size of plate, 75in. 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 kind of 



Spectroscope and Polarimeters. 



ORAM) PRIX. PARIi. iQoo; ST. LOUIS, loo-i. 

 Telegrams: "ARCTITUDE, LONDON." 



W. W^ILSON. 



STUDENT'S SPECTROMETER. 



£6 



Telescope and pjisn 

 cable reading to 1 

 min.; clamp and fine 

 adjustment to both. 

 Rack-molion to tele- 

 scope ; prism table 

 adjustable vertically 

 and horizontally. Ad- 

 justable slit to colli- 

 mator. Protected 



circle. In case. 

 O O 



1 BELMONT STREET, LONDON, N.W. 



(a .simplitied form of Collotype without elaborate plant) for repro- 

 ducing from negatives sfi/Ltu/j,/ pgrmanctit prints, in any colour, 

 equal to Silver, Plalinolype, or Bromide prints. 

 From SS/- 

 E*- Nature says : — ".-Ji n menns ,y <]uukly ohtahdiis: pcr- 

 iiuituilt prints from pliotoi;rapliic negatives it s/wiil,/ prove 

 oxtrcmely use/uir ] 



»> 



THE BLACK BOX, 



a light, compact, folding, portable, cloth da'kroom, on the umbrella 

 principle. Indispensable to Amateur Photographers, &c., for 



changing plates in daylight. 



gm~ Nature says :— '• i/j<//(/ to i-jery photographer, '.vluthcr 



Amateur or Professional, Tuiiilst traveling;" 



Write for Specimens, *c., or call and see these useful Inventions. 



AUTOCOPYIST CO. (Dept. 1), 64 Queen Victoria St., London. 



SELF-IiUMINOUS 

 RADIUM SCREENS 



(CLEW'S PATENT), 5s. each. 



Always visible in the dark at a distance of many 



yards. 



Radium Screens are charming objects in the 



microscope, giving a magnifieent display of 



Scintillations. 



F. H ARmi^olsTGL E W, 



RADieGRaPHER, 



156 CLAPHAM ROAD, LONDON, S.W. 



LIQUID AIR AND LIQUID HYDROCEJir. 



Dr.HAMPSONS AIR-LIQUEFIER 



nber- 



Unh 



made to a standard pat 

 y Laboratories and elsewhere ir 



various countries. The whole apparatus is neat and compact and its pans 

 very easily moved ; the Liquefier, without stand, being a cylinder 17 inche. 

 high and 8 inches in diameter. 



It begins to liquefy air in from 6 to 10 minutes after the admissioD o*" air 

 at from 15010 200 atmospheres pressure, making over a litre of liquid per 

 hour. 



It requires no auxiliary refrigerant and produces a perfectly clear liquid 

 which requires no filtr-ring 



The onTatoT ha': only nne gauge to watch and one valve to control. 



HYDROr.RN l.K^UEFIER to the designs of Dr. MORRIS W. 

 TRAVERS for u-^e in conjunction with Air-Liquefier. 



For Prices and Particulars apply to the Sole Makers : — 



BRIN'G OXYGEN COMPANY, LIMITED, 



ELVERTON STREET, WESTMINSTER, S.W. 



