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THE POPULAR SCIENCE MONTHLY. 



tiring which we term the atom. Such a ring 

 in Mich a medium would be indestructible, it 

 would be elastic, and the size of the ring and 

 its rate of motion would constitute the differ- 

 ences which we recognize between the ele- 

 mentary substances, instead of these differ- 

 ences being due to the size and shape of ul- 

 timate hard particles and their impressed 

 forces. 



In this view matter itself becomes but 

 a mode of motion, and the old conception of 

 forces as entities disappears. Everything is 

 in the last analysis reducible to motion in the 

 ether, and whether any given set of motions 

 manifest themselves as heat, light, or elec- 

 tricity depends upon the character of the 

 motions. The ether is at once the medium 

 for the transfer of all motion and the store- 

 house of all energy. 



Prof. Dolbear has set forth these new 

 views of modern physics briefly but clearly, 

 and without calling upon the reader for more 

 knowledge than that possessed by the aver- 

 age cultivated man. He does not present 

 them as demonstrated science, but as the 

 views which are gaming ground among scien- 

 tific workers, and which hold out the promise 

 of our ultimately understanding, in some great- 

 er measure than now, the ultimate structure 

 of the physical universe. 



Waterdale Researches ; or, Fresh Light 

 on the Dynamic Action and Ponder- 

 osity of Matter. By "Waterdale." 

 London: Chapman & Hall, 1892. Pp. 

 293. 



Since Newton first announced the law of 

 gravity there have been innumerable at- 

 tempts to formulate some working hypothe- 

 sis of a mechanism by which the observed 

 results might be produced. Newton himself 

 repudiated the idea of the particles of mat- 

 ter acting upon each other through void 

 space, and, though this conception of iso- 

 lated particles endowed with attractive forces 

 is commonly made use of in mathematical 

 analysis, it has never been regarded by 

 physicists as answering to any reality. They 

 have recognized that the universe must be a 

 plenum, and that gravity must in some way 

 result from strains set up in a medium which 

 fills all space. This view is now taking on 

 more definite shape, and it is hoped that be- 

 fore a great while it may be possible to 



frame some intelligible and consistent theory 

 of the operation of gravity. 



To do this appears to be the purpose of 

 "Waterdale" in these "researches," as he 

 is pleased to call them. The book does not 

 seem to have met with a very favorable re- 

 ception in England, where it was published 

 in the summer of 1891, and the author, 

 therefore, prefaces the present volume with 

 a wearisome plaint over his lack of recogni- 

 tion by scientific men. A dip into the book, 

 which is all we have had time for, seems to 

 amply confirm the judgment of the English 

 scientific world. It may be that the author 

 has arrived at some valuable ideas on the 

 subject, but until he either puts them him- 

 self in readable English or has some one else 

 do it for him he has not much cause for 

 complaint if busy men refuse to spend time 

 in hunting for the kernel of truth which may 

 lie hidden. 



Ethan Allen, the Robin Hood of Ver- 

 mont. By Henry Hall. New York : 

 D. Appleton & Co. Pp. 207. 



The purpose of the author of this work, 

 who died, leaving it for his daughter to com- 

 plete, was " to make a fuller life of Allen 

 than has been written, and, singling him 

 from that cluster of sturdy patriots in the 

 New Hampshire Grants, to make plain the 

 vivid personality of a Vermont hero to the 

 younger generations." A picturesque hero 

 he is made to appear. Had the records 

 been less exact and romance been left to 

 deal unrestrained with his career, he might 

 in time have shone forth comparably with 

 the most airy heroes of ancient myth and 

 saga. He is compared with Robin Hood 

 that is, the Robin Hood of Ivanhoe whose 

 life was "an Anglo-Saxon protest against 

 Norman despotism," as Allen's life was " a 

 protest against domestic robbery and foreign 

 tyranny." Although never a citizen of the 

 United States, " he is one of the heroes of 

 the State and the nation." While we find 

 much about him to study profitably and ad- 

 mire, there are some features in his career 

 that we can not unqualifiedly commend for 

 imitation by our youth ; neither can we cen- 

 sure him, for he acted according to his con- 

 science, and consistently for a single end 

 the freedom of Vermont. He is best known 

 for the capture of Fort Ticonderoga ; but 



