= 
736 REVIEWS AND BOOK NOTICES. 
the liberality of our government in causing these explorations to 
be carried out, and in placing the results directly before the people. 
We shall return to this report in a subsequent number of this 
journal, and notice the results contributed by Prof. Hayden’s 
collaborators. 
After all, the discoveries here published are the results of but a 
slight reconnoissance, and we trust that this is but the beginning 
of a long series of annual explorations, so that the outlines here 
sketched may be filled in with a completeness worthy of the subject. 
ELEMENTS OF PaysicaL Maniputation.* — This book would, 
perhaps, have never seen the light, or even been conceived of in 
the olden time of endeavoring to instruct students by talking at 
them from behind a formidable array of retorts, balances and 
batteries. By the new method the student is invited into the lab- 
oratory, and initiated into the use of the apparatus, of old so mys- 
terious and awe-inspiring to the beginner. The tools of the 
physicist and chemist are now explained and their use illustrated ; 
and, equipped with a knowledge of manipulation, the learner 
needs little urging to apply his information. 
This text book of physical manipulation seems admirably adapt- 
ed to aid the teacher in work of this kind, and for those who have 
not the advantages of competent laboratory instruction it seems 
to us that it must prove invaluable. It is also admirably designed 
as an introduction to the ordinary text books. 
Judging by the portion relating to the use of the microscope, 
the style is exact and clear. The spectroscope, both solar and 
chemical, is described, and experiments in its use given. So for 
the microscope. The instrument is described, and experiments 
illustrating its use given, also an account of the diaphragm, 
oblique illumination, the study of opaque objects, the lieberkuln, 
Wenham’s parabolic condenser, the achromatic condenser, the 
polariscope, binocular, Maltwood’s finder, micrometer, goniometer, 
camera lucida, spectrum microscope, and test objects, together with 
concise directions for the preparation and mounting of objects, 
and directions for measuring the focal length of an objective. 
Prof. Pickering claims that among the experiments, several that 
are new, with new apparatus, such as that for ruling scales, the 
ute, tee 
* Elements of Physical eased eg sd Edward C. Pickering. New York. Hurd 
and Houghton. 1873. 8vo. pp. 225. $3.00. 
s 
