1964 Journal of Applied Microscopy 



A simple test with the magnet, streak stone, or blowpipe, or a demonstra- 

 tion under the field microscope readily dispels their doubts. In addition to the 

 geological hammer and pick, one must carry a camera and tripod, books, note 

 books, maps, clinometer, barometer, thermometer, altimeter, compass, blowpipe, 

 and other things, on ordinary occasions, with a microscope for certain occasions. 

 Add to all these the clothing necessary for the trip, and the hand luggage becomes 

 sufficiently burdensome to render compact apparatus very desirable, if not actu- 

 ally necessary. Finding a good pocket magnifier a necessity, and a pocket 

 microscope an important adjunct to the traveling kit, and finding none of these 

 things in the market, drawings were prepared from which the Bausch & Lomb 

 Optical Company made the two glasses described and figured here. 



Next to his penknife and watch, the geologist uses his pocket magnifier most, 

 hence it ought to be first-class, and as well made and as good optically as means 

 will allow, in order that it may be lived with somewhat as one lives with his 

 watch, which is chained to him. The price of so inseparable and indispensable 

 a pocket companion is not to be considered so much as its quality, seeing it is 

 likely to be with one for a lifetime, and ought to be the very best from the outset. 



The idea was to design a pocket magnifier which should fit in the vest pocket, 

 or in the fob like a small flat watch, free from angles and corners. The size of 

 the one shown here may be still further reduced by dispensing with the compass, 

 although it is a great convenience. The expense may be lowered by substituting 

 ordinary lenses for the Hasting triplets and by mounting in rubber instead of 

 metal, if need be. One is less aware of the presence in his pocket of such a 

 watch-like magnifier, than he is of the smallest ordinary pocket lens with its 

 edges and rings. 



Three magnifications are obtainable, namely: 5, 10, and 20 diameters. The 

 writer finds this particular form strong, compact, optically the very best, and 

 mechanically just to his liking. It is chained fast, and is never missing or out 

 of place, and altogether may be pronounced a convenient and desirable magnifier. 



A POCKET MICROSCOPE. 



A pocket microscope, or field microscope, though less easily designed, is 

 nevertheless a possibility, and furthermore it may be small enough to carry in 

 the vest pocket, the entire size being scarcely larger than an objective case. Of 

 course such a microscope lacks the high magnifying power and the conveniences 

 of the laboratory stand, but it makes up for this in a compactness such that it 

 occupies but a mere corner in one's traveling bag. Besides, in field work, high 

 power and convenience are not essential, since the objects to be determined are 

 generally large, such as volcanic ash, chalk, clay, silt, sand, and other relatively 

 coarse material, though that as fine as diatomaceous earth is readily resolved. 

 In many localities these materials are not easily distinguished by the eye, 

 but are instantly detected by this pocket microscope. The following magnifica- 

 tions are obtained, namely, 100, 60, 40, 30, 20, and 15 diameters, which serve 

 the purpose. Besides, the optical parts may be adapted to the dissecting stand, 

 and can thus serve a double purpose. 



One of the best features of this little field microscope is the conviction which 



