1 3 2 



POPULAR SCIENCE MONTHLY. 



leaf can not be profitably studied with 

 out a knowledge of its structure and 

 functions; and it is also important to 

 know' what is the systematic position 

 of each of the various plants whose 

 leaves afford the material for study. In 

 a word, the student should not attempt 

 to read the book straight through from 

 the beginning as if it were a novel. On 

 the contrary, he may begin with any 

 one of the four parts as his main sub- 

 ject; but that part must be studied in 

 close relation with the other three 

 parts"; and this method of proceeding 

 is facilitated by the insertion of a large 

 number of cross-references in the text. 



A satisfactory account is given by 

 C. Francis Jenkins in Animated Pic- 

 tures * of the development and present 

 state of chronophotography, or the art 

 of " conveying by persistence of vision 

 a counterfeit impression of objects in 

 motion through the display in rapid 

 succession of a series of related pic- 

 tures." The story shows very clearly 

 that this, like most other inventions 

 of consequence, is no sudden discovery, 

 but is the culmination of a very long 

 series of experiments. The principle of 

 it is embodied in the toy, the zoetrope, 

 the origin of which is not known, 

 though a citation from Lucretius indi- 

 cates that something of the kind ex- 

 isted in his time. With the discovery 

 of instantaneous photography, a new 

 application of the principle of the zoe- 

 trope was found. Muybridge and 

 Marey were pioneers in this develop- 

 ment with their photographs of the mo- 

 tions of animals valuable in sciences. 

 Since their work was begun the photo- 

 graphic processes and apparatus have 

 been greatly improved. Mr. Jenkins 

 forecasts a brilliant and useful future 

 for the art, which he hopes will be pros- 

 ecuted along the line of other than its 

 present most popular uses. The book 

 is practical as well as historical and 

 prophetic, and contains an account of 

 Mr. Jenkins's phantoscope as the first 

 successful " moving picture projecting 



* Animated Pictures. An Exposition of the 

 Historical Development of Chronopbotogr ^phy. 

 its Present Scientific Application and Future Pos- 

 sibilities, and of the Methods and Apparatus em- 

 ployed in the Entertainment of Large Audiences 

 by Means of Projecting Lanterns to give the Ap- 

 pearance of Objects in Motion. Washington, 

 D. C.: C. Francis Jenkins. Pp 118, with plates. 



apparatus," for -which he received the 

 Elliott Cresson medal from the Franklin 

 Institute. 



The Metric System of Weights and 

 Measures, prepared by Mr. A. D. Risteen, 

 and published by the Hartford Steam- 

 Boiler Inspection Company, Hartford, 

 Connecticut (price, $1.25), gives what 

 has long been wanted a neat volume, 

 convenient for the pocket and durably 

 bound, furnishing tables for instantly 

 converting all the metrical units up to 

 one hundred of each into those of the 

 English weights and measures, and vice 

 versa. Calculation, being needed only 

 for the numbers above one hundred, for 

 which there are already short devices, is 

 reduced to the lowest possible limit. 



Terrestrial* Magnetism, an interna- 

 tional quarterly journal, edited by L. A. 

 Bauer and Thomas French, Jr., and 

 published at the University of Cincin- 

 nati, is the recognized organ of the In- 

 ternational Conference on Terrestrial 

 Magnetism and Atmospheric Electrici- 

 ty. The September number, 1898, con- 

 tains the proceedings of the conference, 

 which met in connection with the last 

 Bristol meeting of the British Associa- 

 tion. It contains in full the welcoming 

 address of Prof. W. E. Ayrton, the open- 

 ing address of A. W. Riicker, president 

 of the conference, and ten of the papers 

 read at the meeting. 



The name of Prof. John Trowbridgc 

 as author of such a book as Philip's 

 Experiments; or, Physical Science 

 at Home (D. Appleton and Company, 

 $1) is a sure guarantee of its scien- 

 tific value. The author has given a 

 chapter substantially out of his own ex- 

 perience, for he says his taste for sci- 

 ence and for drawing were stimulated 

 by his father in the manner here de- 

 scribed. His object in publishing it is 

 ' to show that a few moments devoted 

 jach day at home to simple investiga- 

 ;ions can result in habits of self-reliance 

 n the acquirement of a modern lan- 

 guage and in the study of the art of 

 drawing." He endeavors also to show 

 low to cultivate a taste for mathe- 

 matics by studying practical problems 

 n surveying and in sailing a boat; and 

 how much a parent can accomplish in 

 he formation of a son's tastes without 

 special knowledge, and without the ex- 

 jenditure of much time and money. 



