68 SOME NE IV BOOKS [july 



A HISTOKY OF EXPERIMENTAL PHYSICS. 



Geschichte der physikalische Experimentier-Kunst. By Drs. Gerland 

 and F. Traumuller. 8vo, pp. xvi. + 442, with 425 illustrations. 

 Leipzig: Engelmann, 1899. 



To trace from their hazy beginnings the gradual and laborious development 

 of what are now familiar and simple truths is always a fascinating study. If 

 rightly pursued it should give us a psychological insight into the mental modes 

 of man. One great difficulty must ever be the imperfection of the historic 

 imagination. Just as the mature intellect is apt to misinterpret the modes of 

 thought of the child or savage, so we, the heirs of centuries of accumulated 

 knowledge, have difficulty in appreciating the intellectual needs and powers of 

 our ancestors. Where, however, as in the case before us, the mark of the stage 

 of culture arrived at is a mechanical contrivance or an illustrative experiment, 

 there is less play for the personal equation, there is more chance for a sound 

 judgment. Doctors Gerland and Traumuller have put together an extremely 

 interesting book in which is presented, on its purely experimental side, the 

 evolution of physical science from the early days of the Assyrians, Egyptians, 

 and Greeks, through the times of the Middle Ages to the end of the sixteenth 

 century, when with Galileo the modern school of experimental science may be 

 said to have begun, and from this epoch on to our own days. Nearly a century 

 before Galileo's time, however, we find in Leonardo da Vinci — famous even in 

 his own day as painter, sculptor, musician, architect, and engineer — a type of the 

 true scientific spirit. Particularly fruitful were his inventions and discoveries 

 in hydraulics. 



To give a fair notion of the contents of the book, suffice it to say that it 

 is chiefly concerned with the invention of such familiar instruments as the 

 telescope, microscope, pendulum, air-pump, thermometer, barometer, hygro- 

 meter, the electric machine, voltaic cell, galvanometer, induction coil, tele- 

 graph, etc. 



The cuts and illustrations are numerous and instructive. Many are 

 reproduced from original sources, and some are of high interest. Perhaps the 

 most curious is the picture of von Guericke's experiment showing two teams of 

 horses (sixteen in all) engaged in " a tug of war," the object being to pull asunder 

 two gigantic Magdeburg hemispheres within which a vacuum has been formed. 

 Very instructive also are the ingenious mechanical devices employed by our 

 scientific forefathers to illustrate or demonstrate important mechanical principles. 

 Not a few of these might with advantage be introduced for demonstrative 

 purposes in our schools and colleges. C. G. K. 



POPULAR ENTOMOLOGY. 



True Tales of the Insects. By L. N. Badenoch. 8vo, pp. xviii. + 255, with 

 44 figs. London: Chapman and Hall, Ltd., 1899. Price 12s. 



It was a happy inspiration of the author to devote most of this handsome 

 volume to insects with stories of such interest and so little hackneyed as are 

 those of the Orthoptera. Though popular in aim the book bears evidence of a 

 true love of entomology and of a knowledge of the creatures described that are 

 far from universal in similar works ; and few readers will lay it down without 

 the desire to learn more of its subject. The essays on Lepidoptera, which 

 occupy the last eighty pages, are scarcely equal to the others. 



Unfortunately the literary form often leaves a good deal to be desired. 

 Such sentences as these are too frequent : — " Others again can fly, having ample 

 wings, and, oddly enough, often gaily coloured. Look at the large spectre 

 Acrophylla titan of Australia, a giant of its kind ; its charming wings generally 



