SCIENCE-ADVERTISEMENTS 



Precision Optleol Instruments 



MADE BY ADAM HILQER, Ltd. 



HllK r Qaartz Spectroi,raph, Sl/e C 



The firm of \dam Hilger Ltd mamifictmes a larte ai J oinprehcnsiTe line of precision optical instruments. 

 For the perfection of the optical and mechanical construction of their instruments this firm is well known all over 

 the world. The following is asuggestive list of the instruments manufactured :— 



Wavelength Spectrometers, Monocliromatlc Illuminators, Uvlol Glass and Quartz Spectrographs, Fery 

 Spectrograph, Houston Polarization Photometer Attachment, Nutting Polarization Photometer Attach- 

 ment. Pocket and other direct vision Spectroscopes, Micrometers, Polarlmeters and Kefractometers, 

 Fery Kefractometers, Interferometers, Spectrocoplc Apparatus for High Resolving Power, Solar and 

 Stellar Spectroscopes, Spectrometers, and Goniometers for general work, Accessories of all kinds for 

 use with instruments. 



As special representatives of Adam Hilger, Ltd.. in this country we are prepared to furnish latest catalog 

 matter and also further details and quote best prices for special duty-free importation. 



Write to-day for Catalog 



JAMES G. BIDDLE 



1211-13 ARCH ST. Special Representative PHILADELPHIA 



When in Philadelphia he sure to visit our Permanent Exhibit of scientific apparatus. 



"GREENOUQH LEITZ" 



Stereoscopic Image Erect= 



ing Microscopes 



Embodying a new type of construction, 

 providing greater stability than in all 

 previously existing models. 

 Rigid adjustments of microscope tubes 

 with Porco Prisms is assured by the plac- 

 ing of rack and pinion independent of 

 such adjustments. 



Patented Elastic Prism Mounting: In 

 Steel Sprinars— same as in our Prism Bi- 

 nocular Field Glaases. 

 Upper part of microscope with prism 

 tubes is removable, for attachment to a 

 special hard rubber foot (wiih indepen- 

 dent rack and pinion coarse adjust- 

 ment), serving conveniently in exami- 

 nation of large surfaces (Dermatoscope 

 Arrangement). 



Paired obj-ctives mounted on self cen- 

 tering slides, and can be adjusted rela- 

 tively to each other. One objective in 

 focusing mount to overcome difference 

 of refraction between the observer's eye. 

 The " Qreenough Leitz " Is aJso made 

 In Folding Form, meeting a long felt 

 demand of those who require this in- 

 strument when in the field. Supplied 

 in a convenient sized morocco case. 



Ask for I^iteratnre ssY 



30 East IStli St. 



