60 



THE AMERICAN MONTHLY 



[March, 1882. 



NOTICES OF BOOKS. 



Practical Microscopy. — By Geo. E. Da- 

 vis, F. R. M. S., F. I. C, F. C. S.. etc., 

 London. David Bogue, 1882. (Cloth, 

 pp. 335. 357 Illustrations. $3.00). 



Recognizing the need of a book of a 

 practical nature for beginners in micros- 

 copy, the author has endeavored to adapt 

 this volume to their wants. 



The first chapters are devoted to gene- 

 ral statements of the principles upon which 

 microscopes are made, and also short de- 

 scriptions of the principal stands of Eng- 

 lish makers, with profuse illustrations. 

 Though mentioning some of the better- 

 known American manufacturers, the au- 

 thor does not describe any of their instru- 

 ments, with a single exception, and seems 

 not to be acquainted with the various 

 American stands of the higher grade, for 

 he makes the rather remarkable statement 

 that the difference in cost of the English 

 and American stands is due to the supe- 

 rior workmanship of the former. 



The preceding chapters are devoted to 

 short, but very concise descriptions of the 

 various accessories and instructions for 

 their use. Throughout the book the au- 

 thor lays great stress upon the compara- 

 tive value of the various accessories and 

 materials for work, advising the student 

 not to encumber himself with a host of 

 expensive accessories which, though use- 

 ful to the expert and professional man for 

 saving time and labor, are of comparatively 

 little value to the student, and always in 

 his way. 



Chapter V is devoted to general remarks 

 upon objectives ; defining very explicitly 

 the terms "working-distance," " definmg 

 power," " flatness of field, and freedom 

 from distortion " " penetrating and resolv- 

 ing power." Numerous tables and dia- 

 grams, and illustrations of test-objects are 

 given. The difference between low and 

 wide-angled, and dry and immersion ob- 

 jectives is also explained and the relative 

 value of each discussed. 



Under the head of " Collection of Ob- 

 jects," the various modes of collecting, 

 and the implements used, are described. 



Considerable space is devoted to dissec- 

 tions and section-cutting, giving many 

 formulae for preparing objects, and the 

 mode of procedure, together with a de- 

 scription of the various instruments em- 

 ployed. 



Micrometry and photo-micrography are 

 concisely described, and the instructions 



for photographing with complete formulse 

 for the preparation and development of 

 plates are worthy of careful attention. 



The micro-spectroscope is explained, 

 and figures of ten spectra are given. 



The processes of staining, injecting and 

 mounting are described at considerable 

 length. 



The indexs is very full and complete, oc- 

 cupying eleven pages. 



It is a book which we can recommend 

 to all who desire to make themselves fa- 

 miliar with the microscope, and is written 

 in a very readable and interesting style. 



H. H. 



Exchanges. 



[Exchanges are inserted in this column without 

 charge. They will be strictly limited to mounted ■ 

 objects, and material for mounting.] 



Unmounted Foraminifera from the north of Ireland 

 for mounted objects. T. B. JENNINGS, 



Signal Office, Springfield, Ills. 



Diatoms, recent, fossil and in situ ; algse, ferns, and 

 much other first-class material to exchange for first- 

 class material of any kind, prepared material, and 

 particularly foreign diatoms, recent and fossil 

 preferred. M. A. BOOTH, Longmeadow, Mass. 



Having secured a supply of the microphotographic 

 films used for transmitting news by pigeon-post during 

 the siege of Paris, I will take pleasure in sending an 

 unmounted specimen, suitable for microscopic use, to 

 any person who will send me a stamped and directed 

 envelope for that purpose. R. H. WARD, M. D., 

 S3 Fourth Street, Troy, N. Y. 



Well-mounted slides of Pathological and Histologi- 

 cal specimens, injected and otherwise, in exchange for 

 Insects, Polariscopic or Pathological slides. 



FRANK P. HUDNUT, Orange, N. J. 



A slide of well-cleaned Epithemia turgida offered 

 for any other well-mounted object or material. 



H. S. WOODMAN, P. O. Box 87, 

 Brooklyn, E. D., New York. 



A beautiful collection of wild seeds of Central Ohio 

 to exchange. List furnished on application. 



F. O. JACOBS, Newark, Ohio. 



Well mounted Diatoms, etc., in exchange for first- 

 class slides, or material. W. H. TIVY, 



6th and Olive Streets, St. Louis, Mo. 



Well mounted Diatoms on Alga, Polycistina, Zoo- 

 phytes various, and other miscellaneous objects for 

 other well mounted objects. Mounted Insects or parts 

 of Insects preferred. W. FARNELL, 



125 Walnut Street, Macon, Ga. 



For a packet of frustules of Biddulphia Itzvis^ send 

 slide, or unmounted specimen to 



K. M. CUNNINGHAM, 



Box 874, Mobile, Ala. 



