March 23, 1888.] 



SCIENCE. 



143 



so, however, as there are numerous additions, and, what is most 

 notable, the plan of the work in one particular differs radically from 

 that of the larger and more complete volume. The original series 

 from which this is derived is intended to serve as a laboratory guide, 

 and must be used in connection with some good text-book. The 

 present volume is so written as to be available as both a text and a 

 laboratory book, but it will probably be found more useful as a 

 working handbook, 'and as an adjunct to a well-prepared text. 

 The explanations of principles are invariably good, but not always 

 sufficient, the necessities of the case requiring a degree of conden- 

 sation sometimes incompatible with great simplicity. In common 

 with the other members of the family to which it belongs, the book 

 has great merit. In the beginning there is an introductory chapter 

 on fundamental measurements and measuring instruments; there 

 is next an excellent chapter on electrostatics, but which will appear 

 to be somewhat long to some American teachers whose ambition 

 seems to be to reach the dynamo-machine in the shortest possible 

 time; then follows a chapter on magnetism ; and the remainder of 

 the book is devoted to voltaic electricity, electrical instruments, and 

 measurements. There is an appendix, which, besides some addi- 

 tional practical hints to teacher and pupil, furnishes a price-list of 

 instruments and materials needed for the laboratory and laboratory 

 workshop, and complete plans, drawn to scale, of three recently 

 established school laboratories. These will be of great service to 

 those contemplating such additions to their school equipment ; and 

 the book, as a whole, can be strongly recommended to all interested 

 in the advancement of elementary instruction in physics. 



Among a few defects of minor importance may be mentioned the 

 strict adherence, peculiar to English authors, to the concave mirror 

 and scale for galvanometer and other purposes, omitting the con- 

 sideration of the plane mirror and telescope method, which is often 

 much better and much more available than the other. Taken in 

 connection with the other series by the same authors, the title of 

 this volume is unfortunate, and likely to lead to considerable con- 

 fusion in making orders, references, or quotations. 



The New Astronomy. By Samuel Pierpont Langlev. Bos- 

 ton, Ticknor. 8°. 



" I HAVE written these pages, not for the professional reader, 

 but with the hope of reaching a part of that educated public on 

 whose support he is so often dependent for the means of extending 

 the boundaries of knowledge. 



" It is not generally understood that among us not only the sup- 

 port of the government, but with scarcely an exception every new 

 private benefaction, is devoted to ' the Old ' Astronomv, which is 

 relatively munificently endowed already ; while that which I have 

 here called ' the New,' so fruitful in results of interest and impor- 

 tance, struggles almost unaided. 



" We are all glad to know that Urania, who was in the begin- 

 ning but a poor Chaldean shepherdess, has long since become well- 

 to-do, and dwells now in state. It is far less known than it should 

 be, that she has a younger sister now among us, bearing every 

 mark of her celestial birth, but all unendowed and portionless. It 

 is for the reader's interest in the latter that this book is a plea." 



The purpose of Professor Langley's book, as well as the charm- 

 ing style in which it is written, are so well set forth in his brief 

 preface, that we have quoted it entire, as above. Supplemented 

 with the clear statement of the opening pages, that the prime object 

 of the old astronomy has been to tell us where the heavenly bodies 

 are, while the new endeavors to tell us what they are, the reader 

 has at Once a clear idea of the scope and aim of this most interest- 

 ing book. Though not written for the professional astronomer, 

 none such can read it without interest and profit, even if for nothing 

 more than as an excellent example of how to present his hard facts 

 in a pleasing and attractive dress ; while every intelligent reader 

 will be pleased not only with the manner of presentation, but with 

 the matter presented ; and so plain and easy is the pathway made, 

 that the unprofessional reader has little idea of the months and 

 years of patient investigation — much of it the author's own — which 

 have made these plain and easy statements possible. Rarely, too, 

 or rather never before in an astronomical work, have engraver and 

 publisher so happily united in giving a literary gem so beautiful an 

 artistic setting. The first chapter especially, on ' Sun-Spots,' is 



rich in beautiful drawings from the author's own pencil while at 

 Allegheny ; and those who recall the wonderful frontispiece of 

 Professor Young's excellent work, ' The Sun,' will desire to feast 

 the eye upon the large number of equally fine drawings in the pres- 

 ent work. Printed at the University Press of John Wilson & Son,. 

 Cambridge, Mass., and upon paper so heavy that the only draw- 

 back is the reader's constant fear that he has turned three or four 

 leaves at once, the whole is a beautiful specimen of the book- 

 maker's art, and a gem which every educated man should possess. 



We can only notice in the briefest way the contents of the eight 

 chapters of the book. The first four are given up to the Sun (and 

 after reading them we think the reader will join with us in a request 

 to the compositor to set this with a capital S). Chapter I., under 

 the title of * Spots on the Sun,' treats of the photosphere, and con- 

 tains reproductions of those beautiful drawings by the authorwhicb 

 we have already mentioned. The second chapter, treating of the 

 chromosphere and corona, naturally draws largely upon govern- 

 ment eclipse-reports for its illustrations. While many of the latter 

 cannot lay claim to much artistic excellence, they are useful as- 

 illustrating very forcibly the difficulties attending the ordinary at- 

 tempts to sketch the corona during the two or three minutes of a. 

 total eclipse, and the need that photography should supplant most 

 of these except for the telescopic detail of the inner corona, which 

 is too fine for the photographic plate, and for the extreme outer 

 limits, for which the eye is much more sensitive. The interesting; 

 drawings of hydrogen-clouds and outbursts above the sun's photo- 

 sphere are naturally nearly all from the works of Young and Tac- 

 chini, who have done so much in this field. Right here, in connec- 

 tion with all the illustrations of the book, we would heartily com- 

 mend the pains taken to indicate the original author or source of 

 every illustration used, either directly under it or in the text close 

 by. This is a matter in which some careless or unscrupulous 

 authors and editors need a sharp lesson. 



Chapters III. and IV. are devoted to the sun's energy, and are 

 the most interesting and instructive in the book. Space will not 

 here allow us to note the exceeding number of interesting features 

 dealt with, and we imagine that the author must have felt over- 

 whelmed in trying to deal at all fully, even in forty-seven pages, 

 with the wealth of important phenomena resulting from the outflow 

 of solar energy. We cannot refrain, however, from noting the 

 author's striking experiment of comparing solar radiation directly 

 with the ' pour ' of molten steel from a Bessemer ' converter,' — our 

 hottest known source of artificial radiations on a large scale. The 

 result showed that the solar surface, even after being dimmed by 

 absorption in its own and the terrestrial atmospheres, gave out, foot 

 for foot, at least eighty-seven times as much heat as the surface of 

 molten steel, and was more than five thousand times as bright. 



In speaking of the exhaustion of the coal-fields, our source of 

 power, the author gives a striking picture of the fair green England 

 of three hundred years ago as compared with its present smoky 

 skies and soot-blackened surface, where the whole island throbs- 

 with the coal-driven engine, and the waters are churned by the swift 

 steamer ; and then, in the role of prophet, he unfolds the future 

 of a few hundred years, when almost certainly the ' all-beholding' 

 sun ' will send his beams " through rents in the ivy-grown walls of 

 deserted factories, upon silent engines brown with rust, while the 

 mill-hand has gone to other lands, the rivers are clean again, the 

 harbors show only white sails, and England's ' black country ' is 

 green once more ! To America, too, such a time may come, though 

 at a greatly longer diptance." And the fourth chapter closes with- 

 the following striking paragraph : — 



" Future ages may see the seat of empire transferred to regions- 

 of the earth now barren and desolated under intense solar heat, — 

 countries which, for that very cause, will not improbably become 

 the seat of mechanical and thence of political power. Whoever 

 finds the way to make industrially useful the vast sun-power now 

 wasted on the deserts of North Africa or the shores of the Red Sea 

 will effect a greater change in men's affairs than any conqueror in 

 history has done ; for he will once more people those waste places- 

 with the life that swarmed there in the best days of Carthage and 

 of old Egypt, but under another civilization, where man no longer 

 shall worship the sun as a god, but shall have learned to make it 

 his servant." 



