XVI 



THE GUIDE TO NATURE— ADJ'ERTISEMENTS 



ally recognized. Their microscopes are 

 found in the laboratories, schools and 

 colleges throughout the country. Mag- 

 nifiers of this make have been in use 

 for sixty years, while it was this com- 

 pany who introduced in this country 

 the stereoscopic prism field glass , a 

 type that is now universally adopted 

 for the better quality glasses. 



Another Grand Prize was awarded 

 the Balopticons, as the projection appa- 

 ratus of Bausch & Lomb manufacture 

 is called. It is believed that this award 

 was granted not only on the general 

 excellence and completeness of this 

 line, but upon the marked improvement 

 in projection apparatus caused by the 

 entry of this company into the field 

 Besides simple stereopticons for lan- 

 tern slide projection, the Balopticons 

 include instruments which project 

 opaque objects direct, that is, solid ob- 

 jects or actual photographs, pictures, 

 etc., without the necessity of making 

 lantern slides. These instruments also 

 project on the screen objects as seen 

 through the microscope and include 

 every other device known in optical 

 projection. 



Bausch & Lomb surveying instru- 

 ments received a Grand Prix tor "(jen- 

 eral Design and Excellence of Qual- 

 ity." These engineering instruments 

 are known to engineers everywhere for 

 the excellence of their optical parts and 

 the number and value of the mechani- 

 cal improvements which these instru- 

 ments introduced as innovations in the 

 field. 



The fourth Grand Prize awarded 

 Bausch & Lomb products was granted 

 upon Range Finders. These instru- 

 ments are used in all branches of war- 

 fare to ascertain the distance of a hos- 

 tile ship or force, and thus obtain the 

 firing range. As '^sed in connection 

 with the big guns of '^""e Toast D'^f*""^'". 

 ''-■p range finders may be stationed a 

 mile nwav fror^ ■'' ' '^'-o-•^' O s 



^nd the range of '^ ^nronching ship^, 

 the various farto'-= r^'-e calculated and 

 the position of the enemy plotted on a 

 chart. Exact directions are telephoned 

 to the ofificer in charge of the firing 

 squad, who may never see what they 

 are shooting at. 



The optical parts of the Bausch & 



Lomb range finders are mounted in a 

 way original with this make. They are 

 suspended upon nickel-steel wires 

 stretched between the ends of the tube 

 under a tension of 10,000 pounds. 

 Bausch & Lomb are now making two of 

 the largest instruments ever built. They 

 are forty feet in length and will be used 

 in the fortifications on the Panama 

 Canal. 



When, in the early days of photog- 

 raphy, Bausch & Lomb began to man- 

 ufacture piiotographic lenses they pro- 

 duced them so cheaply that camera 

 manufacturers were enabled to offer 

 their products at popular prices. The 

 invention of the iris diaphragm shutter 

 helped still further in making picture- 

 taking popular and paved the way for 

 the modern high-speed lens. Hence, 

 when Dr. Rudolph, of the Zeiss Works, 

 invented the modern anastigmat pho- 

 tographic lens, the Zeiss company now 

 collaborators of the Bausch & Lomb 

 Optical Co., designated these manufac- 

 turers as the sole producers for Amer- 

 ica. As a result of the experience and 

 skill gained in this way, the Gold Medal 

 has been awarded to Bausch & Lomb- 

 Zeiss photographic lenses. 



The Photomicrographic Apparatus of 

 Bausch & Lomb make has been granted 

 the Medal of Honor. This apparatus 

 consists of a special camera with appli- 

 ances for using it in connection with 

 a microscope to make photographs of 

 specimens as seen in the microscope. 

 Considerable accuracy and rigidity are 

 required in the mechanical parts and 

 high quality in the optics — for the im- 

 age as received on the photographic 

 plate is magnified a thousand or more 

 times and the slightest tremor of the 

 apparatus or other defect would result 

 in a failure. 



Minerals for Working Collections. 



Ward's Natural Science Establish- 

 ment, 84-102 College Avenue, Roches- 

 ter, New York, has recently issued an 

 attractive pamphlet that gives a list of 

 their minerals and prices. It contains 

 many suggestions in regard to a selec- 

 tion for private cabinets and for school 

 use. We advise our readers that are 

 interested in minerals to send for this 

 pamphlet with a mention of The Guide 

 TO Nature. 



