August 15, 1890.] 



SCIENCE. 



95 



shoiv that there might be a westward motion, by the following 

 reasoning. If the Krakatoa outburst had occurred at a time of 

 year when the temperature was uniform on either side of the 

 equator, say in March and September, then the motion must have 

 been toward the east, but, after March 21 and until June 31, the 

 sun gradually heats up, relatively more and more, portions of the 

 earth to the north of the equator. In consequence of this the 

 bulging of the upper atmosphere does not occur at the equator so 

 much as at circles of latitude farther north. As a result the mo- 

 tion of air particles becomes reversed, that is, toward the equator 

 and not away from it. This would give the particles a tendency 

 to move toward the west, — Q. E. D. This certainly seems like 

 vicious reasoning. In the first place the phenomena of the sky- 

 glows continued until the second week in September, or within 

 ten days of the time when, according to Professor Ferrel, the heat 

 of the sun would have been uniform on either side of the equatoi-, 

 and the motion of the higher strata must have been toward the 

 east if at all. This consideration alone shows how untenable this 

 reasoning is. 



In the second place, let us inquire what the utmost effect can 

 possibly be when the sun is at his farthest north. It should be 

 noted that this heating effect is not directly upon the'atmosphere, 

 but the sun first heats the earth's surface, and that in turn the air 

 above it, and so on. If we can find the air temperature at the 

 earth at various latitudes we can reason from that as to the prob- 

 able heating of the air at some height above the earth. It is quite 

 difficult to determine the heat upon a complete circle of the equa- 

 tor, but, if we take the islands of the sea, we may make an ap- 

 proximation to the true value. The following table gives the 

 temperature of the air at various points: — 



It will be noticed at once that the high temperature of the Cape 

 Verde Islands is due to the proximity of the African coast. It is 

 also true that the exposure of the thermometer is not uniform at 

 these localities. Making due allowance for all irregularities, how- 

 ever, we still find the most remarkable fact, that the air at the 

 earth's surface in July and August is actually at a higher tem- 

 perature on the equator than at a latitude of 23° where the sun 

 may be supposed to be the hottest. This shows conclusively that 

 this seeming heaping up of the air, to the north of the equator, 

 owing to an increased heat from the sun's apparent motion north- 

 ward in July, is entirely mythical; and the only effect that can 

 possibly supervene upon the higher atmosphere must be a motion 

 to the eastward, in all parts of the year, and in the equatorial re- 

 gions as well as to the northward. 



The question will arise. How can these remarkable sky-glows 

 be accounted for? This question does not properly come into this 

 discussion, but a partial answer may be given. The sky-glows 

 were a marked intensification of ordinary sunset phenomena, 

 which it is well known are due to moisture particles. In order 

 that these glows might be seen at their best the following circum- 

 stances were necessary. (1) An abundance of moisture particles 

 at great heights. (3) A clear sky. (3) An abundance of elec- 

 tricity in the air, which would cause the moisture particles to be 

 repelled. We know that the occurrence of such an eruption as 



that at Ki'akatoa does set free an enormous amount of electricity. 

 If any one of these were lacking the glow would diminish or dis- 

 appear. It is known that the glows were of an intermittent char- 

 acter. That the action should have taken place at great velocity 

 from east to west is not at all incredible. Whatever may have 

 been the cause of these glows, we may be absolutely certain that 

 they were not the effect of sun-light upon ashes or products of 

 combustion mechanically distributed by a rapid current from e.ast 

 to west. H. A. Hazen. 



Washington, U.C., Aug. 8. 



BOOK-REVIEWS. 



The Ethical Problem. By Dr. Paul Cartjs. Chicago, Open Court 

 Pub. Co. 12°. 50 cents. 



This pamphlet contains three lectui'es recently delivered before 

 the Chicago Society for Ethical Culture, together with some pre- 

 liminary matter on the same theme. Dr. Carus is deeply im- 

 pressed with the importance of a new basis for ethics, the old 

 traditional foundations having proved insufincient. He maintains, 

 in ojjposition to many leaders of the ethical societies, that a cor- 

 rect theoretical basis of moral action is indispensable, a view with 

 which we cordially agree; and he tells those societies plainly that, 

 unless they supply such a basis, their movement will come to 

 naught. "How can we," he asks, "have a common aim in the 

 'elevation of the moral life,' if we are not agreed upon what a 

 mox-al life is, if our philosophical opinions about good and bad 

 differ?" Accordingly he has prepared these lectures with the 

 apparent purpose of furnishing a basis of ethics, but, we are sorry 

 to say, without success. Indeed, he hardly makes a serious 

 attempt to solve the problem; but contents himself with talking 

 around it and about it, without ever coming to the point. He 

 rejects all the theories of other men, theological, intuitional, 

 utilitarian, and otherwise, and maintains that ethics must be 

 based on "facts" ; but what the true basis is he nowhere informs 

 us. Indeed, we have seldom met with a more unsatisfactory 

 treatment of the question at issue, and we cannot see that Dr. 

 Carus has made any real advance from the position of the ethical 

 societies. 



AMONG THE PUBLISHERS. 



D. C. Heath & Co., Boston, have in press, to be published 

 about Aug. 1.5, a new number in the series of Guides for Science 

 Teaching, published under the auspices of the Boston Society of 

 Natural History. The book is entitled " Insecta," and is written 

 by Professor Hyatt, curator of the Natural History Society. It 

 will be extensively illustrated with engravings from drawings 

 ma(Je specially for the work. 



— Scribner & Welford have the exclusive agency for America 

 of the library edition of Moncure D. Conway's " Life of Haw- 

 thorne," published in England in the Great Writers series. This 

 is printed on larger paper, and, in general, is gotiia up more 

 sumptuously than the twelvemo edition. 



— Frank Vincent, the well-known traveller and author, "in 

 recognition of his distinguished services to the literature of 

 travel,'' has received from the Emperor of Austria the great gold 

 medal for art, literature, and science. This is the second honor 

 Mr. Vincent has received from Vienna, having, a few years ago, 

 been elected a corresponding member of the Austria Geographical 

 Society. 



— Messrs. Longmans, Green & Co. have published a volume of 

 short pieces by the late Richard Jefferies, entitled "Field and 

 Hedgerow." It contains more than twenty essays, mostly on 

 topics suggested by rural scenes and events; but for what purpose 

 such works are written and read we do not know. There is noth- 

 ing in the book but trifling descriptions of natural objects, written 

 in a disagreeable style, with occasionally some brief remark on 

 moral or artistic themes. We look in vain for any contribution 

 to our knowledge of nature, either in its scientific or its esthetic 

 aspect; while the author's remarks on higher themes are singularly 

 vapid and profitless. It may be that somebody will derive either 



