PROFESSOR HUXLEY'S PHYSIOGRAPHY.*
SOME nine years ago Professor Huxley gave a course of lectures at the London Institution under the title of "Physiography." These lectures (which were afterwards repeated at South Kensing- ton) were intended as a general introduction to the study of nature, but until lately those only who had the privilege of attending the courses were enabled to profit by them. Now, however, the short-hand writer's notes have been amplified, some parts rewritten, plates and woodcuts added, and a very charming book produced. In the publication, the author has been assisted by Mr. Rudler, whose well-known acquaintance with natural science has been of great value in editing the book.
The subject is. introduced by an imaginary visit to London Bridge, the observation of the flowing of the stream, and the rise and fall of the tides, and from this starting-point the natural phenomena connected with rivers are fully traced. The stream is tracked upwards beyond the tidal portion of the river, the tribu- taries noticed, and their positions indicated. For this purpose a map is necessary, and incidentally the meaning of a map is explained. It is these incidental references which make the book so delightfel. Many subjects are introduced which seem to have so little to do with the Thames, that on first turning over its pages, it appears like a collection of detached treatises having little relation to one another—chemical experi- ments, meteorological charts, solar protruberances, deep-sea soundings are all included,—but on reading the book from the beginning (and most who begin will continue to the end), it is evident that all these matters are necessary to a thorough apprecia- tion of the subject. There are few writers who could so interweave these various matters into a connected whole without producing in their readers the feeling that such treatment resulted in tiresome di- gressions: no such feeling can possibly be experienced by any intel- ligent reader of Professor Huxley's Physiography, for the subjects come naturally in their proper places—enough is given to illustrate the subject, and never too much. In the matter of the map, for instance, the meaning of the cardinal points must be understood ; for this purpose the mode of finding the meridian by the shadow of a stick is described, also the position of the Pole-star and how to find it, which gives an opportunity, in a foot-note, for stating the way in which stars are named by astronomers. Then we have the mariner's compass and magnetic declination, next the scale of maps, the representation of hills by shading and by contour-lines. When the map is explained, the Thames Valley and river-basin are described, and of the latter a
e Physiography: an Introduction to the Study of Nature. By Professor Holley, 241.11. Landon: Magmillan and Oco. 1878. section from north to south is given, with the necessary caution that the vertical and horizontal scales of such sections are usually different. Then we have an explanation of the term "water-parting," and the advantage of this expression over the more usual one of "water-shed," the chapter ending with the description of a map showing the positions of the river-basins and water-partings of the British Islands. From this somewhat detailed account of the first chapter our readers will obtain an insight into the character of the work, the whole being treated in a similar manner. The second chapter treats of springs, the next of rain and dew, with an excellent plate taken from Mr. R.. H. Scott's instructions in the use of meteorological instruments, of the forms of clouds,—the rain-gauge and hygrometer are here described. In the fourth chapter the properties of snow and 'fee are given ; the fifth is on evaporation ; the sixth on the atmo- sphere, its constituents and its pressure on the earth's surface, which is illustrated by the meteorological reports in the daily papers. Then follow chapters on the chemical composition of pure water and of natural waters, and after these preliminaries we come to the work of rain and rivers in modifying the surface of the earth, first by denudation, and secondly by deposition, then to the action of ice, and lastly to that of the sea. After the study of the action of water in pulling down the elevated portions of the- land, we pass on to the sudden upheaval of land by earthquakes and volcanos, and afterwards to the slow movements which are probably those which have produced the principal changes of elevation and depression of the earth's crust, and are therefore far- more important. The fourteenth chapter deals with living matter and its effects, and the formation of fossils and of coal. Another actioa of living matter is the formation of coral-land, which is succeeded by a description of foraminiferal land, illustrated by references to the expeditions of the 'Challenger,' and to the- author's own investigations of the globigerina ooze obtained from the bottom of the Atlantic during the soundings made before laying the first Atlantic telegraph-cable. Having given these general details of the formation of the earth's crust, the author brings us back to the Thames Basin, first pointing out the im- portant geological evidences obtained from the superposition of strata, and comparing them with a section exposed in Cannon Street in 1851, in which several layers of artificially-formed ground in the middle of London are proofs of the changes which have taken place in its inhabitants. In this chapter some of the organic remains in the Thames Valley are described, and the
evidences given of the existence of prehistoric man by the dis- covery of stone implements. The next chapter deals with the distribution of land and water on the globe and the positions of the principal mountain-ranges, and in the following one- the figure of the earth and the construction of maps are described, together with the uses of the orthographic,. globular and Mercator's projections. The two last chapters treat of the movements of the earth, and the sun, and it is shown that the production of winds, rain, and the variations of climate depend on the relations existing between them, and that if it were not for the heat radiated from our great luminary,, there would be no evaporation, consequently no rain, and none of the phenomena due to water and ice action described in the earlier parts of the book, and that without the light from the sun plant- life could have no existence. This summary will show the extended information the book contains, and most who read it will no doubt desire more detailed instruction on some portions, for which they must refer to special treatises.
The book will be invaluable in producing in young people an interest in the phenomena of nature. It is not a "hard" book ; the subjects are treated simply, and it is needless to add, accu- rately, and all technical terms are explained when they are first used, the words from which they are derived being given in foot- notes. The work will also be useful to teachers as a model of the
method of instruction. A boy is often tempted to ask what is the use of such-and-such learning, but when he is shown that the
most ordinary phenomena of every-day experience require for their elucidation the knowledge of natural laws of which he had previously no conception, he is likely to wish for a more thorough acquaintance with these laws, and to take a de- light in tracing out their working. By thus building on few solid well known facts, the teacher can erect a superstructure of useful knowledge, portions of which will particularly attract the pupil's attention, and encourage him to follow some special branch of natural science, with more earnestness than if he cern- menced the subject without such an introduction. Besides the- advantages the bdok -will possess for teachers and pupils, it cannot fail to interest the ordinary ruder, and thus help to.
diffuse a knowledge of the aims of natural science among the general public.