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THE POPULAR SCIENCE MONTHLY 



Earthquakes," " Lakes and riains," " Rivers 

 and Valleys," " The Sea and its Shores," 

 " Structure of Rocks," and the " Effects of 

 Life." The purpose of the series is to 

 remedy, as far as can practically be done by 

 using the best attainable pictorial illustra- 

 tions, the difficulties besetting the teaching 

 of geology, which arise from the remoteness 

 of the facts on which the teaching must 

 rest, and the present impossibility of the 

 pupil's going and observing them for him- 

 self. Hence, photographs are chosen, when 

 they can be got, on a scale represented by a 

 page as large as that of the current sixteen- 

 page newspaper. The present work was orig- 

 inally designed merely to furnish a collec- 

 tion of photographs of glaciers, along with 

 descriptions that might serve to call the at- 

 tention of the student to the most noteworthy 

 features in the objects represented. The 

 photographs given are bright and spirited, 

 far superior to anything found in books 

 accessible to students, and the descriptions, 

 lucid and satisfactory ; but it was found by 

 the projectors of the work that this would 

 not be enough. The descriptions needed to 

 be supplemented by a connected sketch of 

 the more important part of the subject- 

 matter. The author of the sketch, Pro- 

 fessor Shaler, was compelled by the contract 

 with the publishers to prepare it "with far 

 greater haste than was proper in such a 

 work," a fact which he and the publishers 

 should not have tolerated, for the public 

 have a right in such a work to the best 

 preparation possible; but he has given a 

 comprehensive and excellent review of the 

 whole subject of glaciers and glacial action. 

 The sketch embraces chapters on existing 

 glaciers and their distribution, the distri- 

 bution of ancient glaciers, "The Work of 

 the Glacial Time," " The Origin and Nature 

 of Glacial Periods," "Ancient Glacial Pe- 

 riods," " The Climatal Conditions of Glacial 

 Periods," "The Effect of Glaciers on the 

 Altitude of the Lands," "The Effect of 

 Glaciation on the Life of the Earth," " Rela- 

 tion of Glaciation to the History of Man," 

 "The Movement of Glaciers," "Certain 

 Effects of Glaciers," a glossary, and a bib- 

 liography of the subject. The plates are 

 mostly illustrative of Swiss glaciers, and 

 are arranged so as to show 1. A gen- 

 eral view of glacial form; 2. Details of 



structures from greater to less altitudes; 

 and, 3. Effects of glacial action. A few 

 are added from Norway, the Himalayas, and 

 Colorado, with illustrations of glacial and 

 weather-marks on rocks, and maps of the 

 distribution of glaciers, ancient and modern. 



Adams's Syxchronological Chart of Uni- 

 versal Hictory. Price, $15. New 

 York : Colby & Co., No. 5 Union Square. 



The superiority of the eye as an inlet of 

 knowledge, over all the other senses, is gen- 

 erally admitted, though it is not generally 

 half appreciated. If people will examine 

 the contents of their minds, they will find 

 that far the greatest portion of them are 

 visual acquisitions. It would be a very 

 moderate estimate to say that nine tenths 

 of our ideas are got through the help of the 

 eye. Visual impressions are, besides, of a 

 higher grade than those of the other senses. 

 They are sharper, clearer, and all their re- 

 lations are more definite. Then, again, they 

 are more adherent than any other impres- 

 sions that is, they stick in the mind and are 

 easiest remembered. Visual ideas are also 

 the most perfect that is, all the complexi- 

 ties and fine diversities of nature are re- 

 produced in thought through the eye. At a 

 glance a whole landscape becomes the prop- 

 erty of the mind. Wc think in pictures ; 

 and the highest faculty of the intellect is 

 that which pieces together old pictures and 

 creates new ones. The eye is the only sense 

 that gives us images ; and how far imagin- 

 ing goes in mental processes is shown by 

 the exalted office of the imagination the 

 image-working faculty of the mind. 



From these facts we are led to perceive 

 the transcendent importance of the eye in 

 education. Acquisitions made by light are 

 of course the most lucid. They are not 

 only the most vivid, but the easiest under- 

 stood and the longest retained. Hence, 

 wherever a subject can be illustrated by 

 maps, charts, and pictorial diagrams, there 

 is an enormous gain in the mental econom- 

 ics of learning. 



History is a subject which in its leading 

 facts is capable of treatment by the visual 

 method, as Adams's chart strikingly illus- 

 trates. The events of the world have all 

 occurred in a double relation of coexistence 

 and of sequence. Many trains of occur- 



