Septembee 6, 1912] 



SCIENCE 



317 



is ascribed to Lambert. Long ago, Tisserand 

 called attention in his " Mecanique Celeste " 

 to the fact that this formula was first given 

 by Elder. To Lambert is due the correspond- 

 ing formula for elliptic orbits. 



In so large a volume, containing so much 

 standard material, it is impossible to enter 

 much into details. Nearly all the methods 

 described are abundantly illustrated with nu- 

 merical examples. As the test itself is clear 

 and the author's style nearly always good, 

 there would seem to be no reason why any one 

 with the proper mathematical equipment 

 should experience any difficulty in under- 

 standing it, which can not be said of either 

 Watson or Oppolzer. Without doubt, it is 

 the most valuable work on " Computational 

 Astronomy " which we have. 



W. D. MaoMillan 



Modern Microscopy. A Handbook for Begin- 

 ners and Students. By M. I. Cross and 

 Martin J. Cole, Lecturer in Histology in 

 Cook's School of Anatomy. Fourth edition, 

 revised and enlarged, with chapters" on 

 special subjects by varioiis writers. Chi- 

 cago, Chicago Medical Book Co. 1912. 

 Time was when " microscopy " had a dis- 

 tinct place in the range of the sciences. This 

 was, however, before the day when the micro- 

 scope had become an instrument so subordi- 

 nated to the scientific branches in which it is 

 largely used. That time was marked by a 

 lively curiosity in the world of the very small 

 which expressed itself in the establishment of 

 microscopical clubs, societies. Journals, etc. 



Popular interest in the " microscope and its 

 revelations " seems to have been largely lost 

 at the present day, perhaps as the detailed 

 results of its use have become more public 

 property. This change of attitude which 

 seems to the reviewer a real one is for many 

 reasons to be deplored, so that such a book as 

 the one whose title is given above should have 

 a distinct place as a guide book for amateur 

 microscopists — ^but only as such. Attempting 

 to cov£r, as it does, practically the entire field 

 in which the microscope is applied, it neces- 



sarily falls short as a book for professional 

 workers or serious students in the various 

 fields. 



The book is clearly written, fairly illus- 

 trated with a selection of figures, in general 

 well chosen. The formulas of preserving 

 fluids, stains and similar prescriptions are 

 standard, although the selection often does 

 not reveal a thorough familiarity with the 

 more recent advances in the field. 



Five chapters constitute Part I. on the 

 Microscope and its Accessories. Part LL, fif- 

 teen chapters, is devoted to the technique of 

 animal and vegetable examination by means 

 of the microscope, together with chapters on 

 mounting entomological specimens, crystals, 

 diatomes, etc. Part HI. comprises special 

 chapters by special writers on The Petrolog- 

 ical Microscope, Eotif ers. Mites, Foraminifera, 

 Mosses and Liverworts, The Microscope and 

 Nature Study and the Microscopy of Foods. 



The book is therefore believed to have its 

 place as a means of arousing and encouraging 

 the interest of the layman in the world around 

 him. 



As a book for use in America, by Ameri- 

 cans, however, it is believed that it would 

 meet the demands that will be made of it 

 better if it were to take some recognition of 

 the excellent microscopes put out by such 

 firms as The Bausch & Lomb Optical Com- 

 pany and the Spencer Lens Company among 

 others. The special chapters, furthermore, 

 deal with a peculiarly English fauna. 



B. F. Kingsbury 



NVMBES. OF SPECIES OF LIVING 

 FEBTEBBATES 

 Eecently I have had occasion to make an 

 estimate of the number of known species of 

 living vertebrates. After consultation with 

 a number of specialists, the figures below have 

 been fixed on as a reasonably close approxima- 

 tion to the truth. Thinking these estimates 

 may be of interest to others, I send them to 

 Science to publish for what they are worth. 

 Such figures can not, of course, be accurate if 

 for no other reasons than that in compiling 

 them no attempt has been made to discrimi- 

 nate between forms described as species or as 



