Page:Popular Science Monthly Volume 39.djvu/719

Rh scientific problems. In preparing this edition two especially technical essays have been omitted, another has been divided and the parts relocated, and many corrections and some important additions have been made in various places. Two new papers have been added to the Tropical Nature and other Essays, namely, The Antiquity of Man in North America, and The Debt of Science to Darwinism. This division of the volume comprises also chapters on the animal life, vegetation, climate, and other features of the equatorial zone, tropical humming-birds, the colors of animals and sexual selection, the colors of plants and the color-sense, and the antiquity of man. Among the subjects of the essays on Natural Selection are the introduction of new species, protective resemblances, instinct, the philosophy of birds' nests, and natural selection applied to man.

amateur who would like to possess table-ware, jewelry, or miscellaneous articles plated with silver or gold by his own hands, and the intelligent boy in a plater's shop who wants to supplement his oral instruction with a record of facts and figures that he can not well carry in his memory, will both find their needs supplied by this manual. Much or little electrical and mechanical knowledge may be used in electro-plating: the amateur may make his own battery or dynamo if he desires, or he may buy apparatus of one of the kinds and makes named in this book. The author tells just what kinds are suitable for doing plating, and why, and also describes the vessels, brushes, lathes, etc., required for the work. He next gives a chapter on preparing the work, which includes thorough cleaning and the grinding out of all scratches, pits, and roughness. The latter operation may be done very laboriously by hand, but the amateur will have it done in some shop on a lathe. The operation of "stripping" the remains of the old coating from articles that have been plated before, and the use of "dipping" and "quicking" solutions are also described here. Separate chapters are then devoted to electro-plating with silver, gold, nickel, copper, alloys, and with zinc, tin, iron, etc. All the little points that need attention are touched upon in each case, and in the chapter on silver full directions are given for burnishing the work. The directions are everywhere simple and concise, and the book is not burdened with historical matter, various alternative processes, or elementary science. The volume is amply illustrated, has a portrait of Faraday for a frontispiece, and has an index.

work is based largely upon the article Mammalia, together with forty shorter articles, written by the senior of the two authors for the ninth edition of the Encyclopædia Britannica. The article Ape, by Dr. St. G. Mivart, and several articles by Dr. G. E. Dobson and Mr. Oldfield Thomas, have also been used, with the permission of the writers. This material has been arranged, the gaps between the several parts have been filled, and new matter, especially on the extinct forms and the group Artiodactyla, has been added. Anatomy and classification are the subjects most largely treated, comparatively little attention being given to habits and mental traits. The text is illustrated with three hundred and fifty-seven figures, most of which appear in the Encylopædia articles above mentioned, while some have been drawn for the present volume, and some obtained from other sources. The well-known character of the Britannica is a sufficient index of the high quality of this work.

second volume of this important work goes from Eau de Cologne to Nux Vomica. Its most extended articles are those on Explosives, Fermentation, Gas (Coal, Oil, and Water), Glass, and Glycerin, on the metals Iron, Lead, and Mercury, and on India Rubber, Iodine, Matches, and Milk. The metallurgical articles treat extraction processes with considerable detail, and give