January 1, 1896.] 



KNOWLEDGE 



15 



pneuma, Mr. Stanley puts forth some ingenious specula- 

 tions on the formation of orbits, and discusses the conditions 

 upon which our solar-planetary system may have been 

 formed, giving also suggestions for causes of direction of 

 rotation and revolution of the planets and satellites. 

 Finally, several chapters are devoted to the study of the 

 hypothesis of the formation of the earth under purely 

 nebular conditions. We have only been able to give the 

 barest outUue of the book, but it will suffice to show the 

 character of the contents. Speculative the book un- 

 doubtedly is, but it is suggestive also ; and though some of 

 the ideas developed have little or no foundation in fact, 

 they are worth consideration, whUe, taken altogether, they 

 will help to place the study of the nebular theory upon a 

 broader basis than heretofore. 



Heliyiland as an OrnithohMjkal Observatory. By Heinrich 

 Giitke, C.M.Z.S., &c. Translated by Kudolph Rosenstock, 

 M.A. (Dand Douglas.) Illustrated. SOs. For the last fifty 

 years, day after day and night after night, as Mr. Harvie- 

 Brown says in his preface to this deeply interesting work, 

 Herr Giitke has studied the migration of birds. As is now 



direction, altitude, velocity, and order of migration flights 

 are all dealt with by the author in a masterly and graphic 

 manner, and a chapter on " Meteorological Conditions 

 which influence Migration " is deeply interesting. Herr 

 Giitke's remarks on the change of colour in birds without 

 moulting will prove invaluable as an addition to our scanty 

 knowledge of this subject. The larger portion of the book 

 is taken up with excellent descriptions of the three hundred 

 and nmety-eight species of birds which the author has 

 collected on Heligoland ; but by far the most fascinating 

 and valuable portion is that dealing with their migrations. 

 We may add that the translator has done his work well in 

 preserving the graphic and logical style of the original. 



Movemmt. By E. -T. Marey. Translated by Eric 

 Pritchard, M.A. (Heinemann). Illustrated. 7s. 6d. " Le 

 Movement," the original of this book, which has been very 

 successfully translated by Mr. Pritchard. is one of the most 

 recent and important works of M. Marey, the eminent 

 French physicist. By the aid of chrono-photography in 

 conjunction with many clever devices, the author has been 

 enabled to explain and elucidate in the book before us 



1 Thrust. (From a Chrono-pliotograph on a fixed plate.) From " Movemeut.'' 



generally known, the island of Heligoland is peculiarly 

 suited to be an ornithological observatory. It stands, as it 

 were, as a stepping-stone across the North Sea, both from 

 east to west and from north to south. Very few birds 

 breed on the island, but from January to December, with 

 little cessation, vast multitudes of birds cross and recross 

 it on migration. Each month brings new arrivals with 

 the utmost regularity. Some sweep over without alighting ; 

 others stay a few hours, but seldom beyond a day. 

 An uninterrupted spell of east wind combined with 

 frost and snow brings the greatest numbers ; then they 

 appear, says the author, in " countless multitudes. . . . 

 Indeed, I have known days on which I have seen, far as 

 the eye could reach, in all quarters of the sky, swarms of 

 these birds crossing each other in all directions. . . . 

 In fact, the whole vault of heaven was literally filled to a 

 height of several thousand feet with these visitors from 

 the far North." Ilerr Giitke is no romancer — he deals 

 with hard facts, and his observations will be invaluable to 

 the student of migration. He discounts many theories by 

 his facts, and he believes that the phenomenon of the 

 migration of birds will never be fully explained. The 



many oJ the complicated movements in man, quadrupeds, 

 birds, fishes, creeping things, and even microscopical 

 organisms. M. Marey's experiments have been carried 

 out for the most part at the Parisian Physiological Station, 

 where unique opportunities were granted to him. How 

 well he has used those opportunities may be seen in the 

 study of his book, which will afford interesting and 

 instructive reading to everyone, and a mine of facts for 

 speciaHsts to work upon. The value of the process of 

 chrono-photography in analyzmg movement may be 

 gathered from the fact that sixty images of a moving 

 object can be produced per second, and thus every stage of 

 its action can be traced. This book contains many re- 

 productions of such photographs and numerous diagrams, 

 important and useful to all in elucidating the text, besides 

 being of great value to the artist for correctly depicting 

 hving creatures in movement. 



Xaturf tcrsus Xatttral S.Uvtion. By Charles Clement 

 Coe. (Swan Sonnenschein.) 10s. 6d. Men of science 

 are almost of one mind as regards the main fact of organic 

 evolution, but they are not in unison as to the process by 

 which the result has been brought about. The great 



