January, 1903. 



KNOWLEDGE, 



13 



Miss Gierke's qnaliflcations for her task are unique. The 

 first requisite — patient industry — has been preeminently hsrs. 

 The thoroughness with which she worked over the ground 

 covered by the astronomers of the earlier part of last century, 

 and the persistency with which she has kept her finger on the 

 pulse of the science, from the time when she first commenced 

 the work, are most remarkable. But the " History " is far 

 indeed removed from any mere dr3'-as-dust compilation, 

 for with rare judgment she orders fact and theory in their due 

 l)roportious, pointing out their accordances, discrepancies, and 

 contradictious ; the accordances which establish the truth of a 

 theory ; the contradictions between fact and theory that cry 

 out for the reconstruction of the latter ; the discrepancies which 

 so often point out the openings to n^w avenues of knowledge. 

 But great research and rare judgment may be, and indeed often 

 are found together in a book that is almost unreadable, through 

 the writer's powerlessness of e.xpressiou. But not here, for 

 Miss Gierke's literary skill and brilliant style are even more 

 apparent than ber industry and judgment. It may be possible 

 to find here an important observation overlooked, or there a 

 wrong conclusion, but throughout the whole volume it would 

 be impossible to fiud a dull page or an ambiguous sentence. 



Where the whole is so excellent it may seem somewhat 

 ungracious to call attention to what is perhaps little more than 

 some dust on the balance, but Miss Gierke herself has led the 

 way for its removal by reversing many of the conclusions 

 recorded in the earlier editions. 



One of these conclusions still finding place in the fourth 

 edition is the too close connection claimed for Carrington's and 

 Hodgson's " white patches" of solar light on September 1, and 

 the magnetic disturbances of the same day. It is trne that a 

 great magnetic storm raged from August 28 to September 4, 

 but at the actual time of Carrington's observation there was a 

 lull in this storm, and, as Mr. Ellis pointed out in Nature for 

 1803, the magnetic trace was but disturbed by a small " twitch " 

 of such a common and ordinary character, that we cannot believe 

 that it was any direct result of the solar outburst. Such 

 "twitches" have been noted since at all periods of sunspot 

 activity, but Carrington's observation has never been repeated. 



In another case Miss Gierke fails to see the force of her own 

 reasoning with respect to the constitution of the planet Venus. 

 In one place she says: — "We are almost equallj- sure that 

 Venus, as that the earth is encompassed with an atmosphere.'' 

 In another, when discussing spectroscopic observations of the 

 planet : " Some additions there ifideed seem to be in the 

 thickening of a few water and oxygen lines ; but so nearly 

 evanescent as to induce the persuasion that most of the light 

 we receive from Venus has traversed only the tenuous upper 

 portion of the atmosphere. It is refiected at any rate with 

 com])aratively slight diminution." And again : " The reflective 

 power of Venus must be singularly strong. And we find, 

 accordingly, from a comparison of Ziillner's with Midler's 

 results, that its albedo is but little inferior to that of new-fallen 

 snow ; in other words, it gives back 77 per cent, of the luminous 

 rays impinging upon it." Now it is evident from these observa- 

 tions that we do not receive light from Venus herself, but only 

 from the outer surface of her atmosphere, and that therefoi'e it 

 is not possible for us to see the configuration of the planet's 

 crust. Miss Gierke acknowledges this, but in the matter of the 

 planet's rotation, she is overpowered by the positive assertions 

 of careful and trustworthy observers that markings seen by 

 them have altered their position ; more especially is she 

 influenced by the groat names of Schiaparelli and Lowell. 

 Since the publication of the " Historj','' Mr. Lowell has with- 

 drawn his observations of radiating markings on Venns, as 

 evidence showed them to be subjective ; and as for other 

 observers, their many discrepancies seem indeed but to strengthen 

 tlio theoretical position that we do not and cannot see the seas 

 and continents of Venns and their I'otation, be it fast or slow 

 I'ound her axis. 



"JOUKNAI. AND PuOCEEDINGS 01' THE ROVAI. SOCIETY OP 



New South Walks." — One of the most interesting pa])ers in 

 this volume is by Mr. (K H. Knibbs, r.n.A.s., on "The Principle 

 of Continuity in the Thoor^y of Space." The subject is treated 

 with more lucidity than might have been expected whore not 

 only pure but pseudo-homuloidal space of /(-dimensions is taken 

 into account. It is obvious, as the author puts it, that if we 

 define a ])oiut as of zcro-dimonsioti (as Euclid does) the con- 

 tinuous generation of a finite quantity by a finite number of 



additions is not a conceptual possibilit}'. We cannot agree with 

 him, however, that it is any less obviously inconceivable that 

 such a quantity can bs continuously generated by an infinite 

 number of point additions. Where the zero is absolute, and not 

 merely a quantity which is infinitely small, the summation of 

 an infinite number yf such zeros cannot result in the genera- 

 tion of a finite quantitj', even though the infinity were of a 

 very large order. 



"Our Country's Fisiie-s .\nd How to Know Them." 

 By W. J. Gordon. (Simpkin.) Coloured plate. 6s. — This 

 little book, com|)iled from various sources, is intended to be used 

 as a key by those who may desire to identify the adult forms of 

 any of our British fishes. The style of composition leaves 

 much to be desired, to say nothing of accuracy. Thus we are 

 informed that " the flat-fish start as very thin youngsters 

 swimming the ordinary way up ... . and their eyes in the 

 normal places, one on each side of the head ; but apparently, 

 failing to thrive under these conditions, they betake themselves 

 to the ground where .... their head turns over so as to bring 

 both eyes on the top. . . ." ! Again we read, " Some are said 

 not to know a sole from a lemon sole : the only way out of the 

 difficulty is to know what a sole is like, the lemon sole being 

 what may be called various, and generally but a somewhat 

 distant relative " ! Minor inaccuracies are of course inevitable, 

 they will creep in despite the greatest care ; on these then we 

 will be silent. 



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