322 NATURE-STUDY REVIEW [16:7— Oct., 1920 



use for themselves. There are many species of these that rob the bees and 

 wasps of their hard-earned possessions. This is a volume for the general 

 reader for it is full of interesting information, at the same time it is a valuable 

 book of reference in the library of the biologist. It contains 39 fine illustra- 

 tions from photographs. While the books deals largely with English species 

 yet it discusses very many American species as well as those from other 

 countries. 



Common Science. Carleton W. Washbume, Superintendent of Schools, 

 Winnetka, 111. 390 pages, illustrated by photographs. World Book Co., 

 New World Science Series, edited by John W. Ritchie. 

 Fifty years ago Physics as taught in Seminaries and Colleges had to do with 

 the phenomena of every day life and was a most attractive study. Later the 

 advanced physics as taught in the Universities dribbled down to the High 

 Schools and too often made the subject difficult and unattractive. The 

 introduction of the Junior Science work in the schools was looked upon askance 

 at first for fear that here again we should have grown up subjects compressed 

 into capsules fit for children's throats so that they might be stuffed with more 

 things. Happily teachers who have an understanding of the child mind have 

 come to the rescue and this Common Science volume is as encouraging as it is 

 pleasing for it deals simply and most interestingly with the common phenomena 

 of a child's environment. The book begins with "Gravitation" which we all 

 experience but of which we know so little; it suggests that we play that we 

 fit up a cabin with all comforts and move out into space 160,000 miles to the 

 spot where the sun's gravity would just balance the earth's gravity and where 

 therefore there would be no gravity. Here, "when you try to walk you glide 

 toward the ceiling. If you push on the ceiling, you float back toward the 

 floor." "There is no up or down — you discover this quickly enough when you 

 try to pour a glass of water. No matter how you hold the pitcher and glass 

 the water will not pour. Finally you have to put your hand into the pitcher 

 and pull the water out. It comes. Not a drop runs between your finp-ers — 

 which way can it run since there is no down? The big lump of water stays 

 right in your hand. This surprises you so much you let go of the pitcher. 

 Never mind; the pitcher stays poised in mid air," and thus on for two pages 

 of delightful imagining, that probably for the first time will show the child 

 what gravity means to those living on the surface of the earth. The topics 

 dealt with are Gravitation, Molecular Attraction, Conservation of Energy, 

 Heat, Radiant Heat and Light, Sound, Magnetism, Electricity, Mingling of 

 Molecules, Chemical Change and Energy, Solution and Chemical Action, 

 Analysis. What a list of grown up topics! However, each chapter resolves 

 itself into explanations of things which every child sees and notices. For 

 instance in the Inference Exercise in Molecular Attraction is "Explain the 

 following: When you wet your finger you can turn a page more easily; a 

 lamp wick draws oil up from the lower part of the lamp to the burner ; when 

 your hands are cold you rub them together to warm them." Under electricity 

 the following are a few of the topics discussed: "Why do you get a shock if 

 your hands are wet when you touch a live wire? Why does a door-bell ring 

 when you push a button? Why can a bird sit on a live wire without getting 



