A LESSON IN ECONOMICS 



In the production of an instru- 

 ment of precision such as a 

 Microscope, requiring not only 

 the work of the trained scientist 

 and high-priced artisan, but also 

 an expensive mechanical equip- 

 ment, it is obvious that there are 

 very distinct advantages in oper- 

 ating on a large scale. 



The magnitude of our business, 

 and the fact that we have one 

 of the largest and best equipped 

 factories in the world, not only 

 enables us to produce a very 

 superior instrument but to pro- 

 duce it at very much less cost 

 than if made on a smaller scale 

 or under less favorable condi- 

 tions. 



BAUSCH & LOMB BH MICROSCOPE 



has been designed especially for use in schools and colleges.^ It is 

 of the handle arm type and can be carried about without injury 

 to the fine adjustment which is unusually responsive. All work- 

 ing parts thoroughly protected from dust. Price complete, with 

 1 6 mm. and 4 mm. objectives, 25 mm. eyepiece, $29.50 ; 

 with double nosepiece, $33.50. 



Bausch & Lomb Optical Co. 



Carl Zeiss, Jena 

 Offices 

 New York 

 Boston 



Chicago 



George N. Saegmullei 

 San Francisco 

 Washington 

 London 

 Frankfort 



ROCHESTER. N. Y. 



For showing on the screen opaque objects, book 

 Illustrations, engravings, and lantern slides. 

 It is the most perfect instrument of its kind. 

 It has a detachable Book -Holder. 

 It concentrates all light on the object, 

 It shows printed matter correctly. 

 It is in use at 



Harvard, Cornell, U. of P., Leland 

 Stanford, Girard College and 

 hundreds of other institutions. 



Wireless Telegraph Outfits 



For school room and experimental work. Com- 

 plete sending and receiving stations. 



Lantern Slides — Microscopic Slides 



Illustrating Botany, Geology and other sciences. 

 Lists on application. 



WILLIAMS, BROWN & EARLE, 

 Dept. N, 918 Chestnut Street, Philadelphia, Pa. 



WATSON & SONS' FRAW MICROSCOPE 



This model is a 

 favorite one with 

 British students 

 and it is especially 

 advantageous be- 

 cause additions 

 may be made to it 

 as may be found 

 necessary or con- 

 venient. 



It has Watson'a 

 diagonal rackwork 

 coarse adjustment 

 and perfected lever 

 fine adjustment. 

 The stage is covered 

 with rubber and it 

 carries an Abbe il- 

 luminator. A late 

 E resident of the 

 :oyal Microscop- 

 ical Society said of 

 it : "A Microscope 

 that can for the 

 first time with truth 

 be called 'good 

 enough for Histo- 

 logical purposes.' " 



Stand only, price £ 4 



With g and j Objectives, 1 ocular and case 6 

 With! and £ Objectives, 2 oculars, Abbe 

 Illuminator with Iris diaphragm, and 

 case 



Illustrated 178 page catalogue of microscopes' and 

 mailed free on request; more than 20 models to select from at S7/6 up 

 Microscopes may be imported free by Educational Institutions. 



WATSON & SONS, Microscope Manufacturers, 



WHOLESALE AND RETAIL 



313 HIGH H0LB0RN, LONDON, ENGLAND 



Established 1837. Awarded 42 Gold and other medals— mlcro- 

 ■copio Objects may be conveniently sent to the U.S.A. by parcel post. 

 American Agents: The Scientific Shop (A. B. Pobtbb) Rooms 1230- 

 1215 Monon Building, 324 Dearborn Street, Chicago, through whom 

 Orders should be sent. 



15 



8 5 



accessories 



e 



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