08 



♦ KNOWLEDGE ♦ 



[Jak. 1, 1886. 



elaborate system has really the attributes of jJermanence, 

 or whether it may be undergoing changes of marvellous 

 rapidity, when the gigantic nature of the objects involved 

 is considered." 



It appears to us that the average reader can easily 

 see, for himself, the features mentioned in the first part 

 of this descriptive (?) passage ; and half a page devoted 

 to an account of what the reader would naturally like to 

 know, but cannot yet be told, is just half a page wasted. 



We had proposed to quote a passage illustrative of Dr. 

 Ball's explanatory method, but we really have not space. 



Take, for instance, transits of Venus: — On p. 143, he 

 tells in a paragraj)h of half a page that there are such and 

 such bodies in the solar system (which the reader already 

 knows from the book itself) ; in another, equally long, that 

 we cannot fully understand a map unless we know its 

 scale ; in a paragraph of three-fourths of a page that one 

 can make a plan of the solar system without knowing its 

 scale. (In the body of this paragraph is a sentence quite 

 out of place, repeating that transits of Venus will give the 

 scale of the solar sj-stem.) One-third of a page shows 

 that when Venus is passing between us and the sun she 

 may be seen on his face. But we learn in two-thirds of 

 a page that she may not, because her plane of travel is 

 inclined to the earth's.* So on and on for page after 

 page — the only attempt at the explanation of the actual 

 transit problem being contained in a paragraph pointing 

 out that if one changes position in a room the window- 

 bars change in apparent position on the distant landscape, 

 followed by remarks showing that the same sort of thing 

 must happen with Venus on the sun. Not one definite 

 statement is made as to dimensions, durations, or the like. 

 (In the earlier and still more general account there are 

 several inaccuracies ; for instance, we are told that " the 

 remarkable eight-year period neceskitates " that a transit 

 in any year shall be followed by another eight years 

 later, which is by no means the case.) Then the old 

 story of early transit observations is repeated — quite 

 proj'erly, of course — after which four pages are given to 

 an account of the observations at the Dublin Observatorj- 

 during the transit of Venus in 1882, made under very 

 unfavourable conditions and without anything of the least 

 importance being noticed. After, in all, seventeen pages, 

 scarcely containing half a page of real matter. Dr. Ball 

 remarks that it is not possible for him, " with a due 

 regard to the limits of this volume, to linger any longer 

 over the consideration of the transit of Venus." But 

 further Dr. Ball persists in lingering'. " When we begin 

 to study the details of the observations we are imme- 

 diately confronted with a multitude of technical and 

 intricate matters. On the occasion of a transit, it has 

 first to be decided where the observations are to be made 

 — in itself a question that has led to no little discussion. 

 Then the instruments that are to be used, and the 

 description of observations to be made, have to be inves- 

 tigated with considerable complexity. The observers must 

 be specially trained for the work, for even Methuselah 

 himself could hardly have lived long enough to have had 

 ranch, jpractice in the observations of transits of Venus, To 



* Two-thircl.s of a page, and more, might quite reasonably be given 

 to cliocidathiri this point : but Dr. Ball does not elucidate it at all. 

 Here is a part of the jjassage, (the bulk is like the sample) : — 

 " If it should happen that Venus overtakes the earth at or near 

 either of the points (1) in which the plane of the orbit of A'enus 

 passes through that of the earth, then tlie three bodies will be in 

 line, and a transit of Venus will be the consequence. The rarity of 

 the occurrence of a transit need no longer be a mystery," kc. A 

 figure showing what is meant, and definite reference to the positions 

 referred to in the description, would have occupied no more space 

 than the paragraph, and would have been far more instructive. 



compensate for the inevitable want of experience, the 

 observers had to be prepared by a special course of in- 

 struction, ia which a fictitious transit was observed. 

 Then, too, the interpretation of the observations involves 

 many thorny and many controverted questions. To 

 pur.sue all these matters so as to render them intelligible, 

 would lead us into great detail and therefore we do not 

 make the attempt. This course (sic) is the more advis- 

 able when it is remembered that the transit of Venus is 

 only one of the methods of finding the sun's distance — a 

 celebrated one, no doubt, but not perhaps the most 

 reliable. It seems not unlikely that the final determina- 

 tion of the sun's distance will be obtained in quite a 

 different manner. This will be explained further on," 

 '' and hence we feel tlie less reluctance in passing away 

 from the consideration of the transit of Venus as a 

 method of celestial surveying." 



Dr. Ball is a powerful mathematician, an able and 

 doubtless faithful observatory chief ; but he has not done 

 his readers or his publishers justice in the book before 

 us. We are not to know on what terms, generous or the 

 reverse, this book has been written ; but for his own 

 credit's sake Dr. Ball ought not, we conceive, to have 

 devoted page after page, in the style we have sampled, to 

 tell his readers that he is unable to tell them what the 

 student of astronomy would naturally like to learn. 

 Those students whose inexperience leads them to imagine 

 as they read page after page of such nothings, that they 

 are following explanations and gaining information, have 

 not been quite fairly treated. 



NEWTON, HIS NAME AND FAME,* 



T may be reasonably questioned how far we 

 have anj' right to inquire into the private 

 life of those from whose thoughts or labours 

 we have profited. That the private lives of 

 kings and queens and other such persons 

 (who are thought to do well when they do 

 no particular mischief) should be inquired 

 into, is right enough ; for the nations do not profit by 

 them, and they cost a good deal ; so that in their case the 

 world has rights for which it has paid more than a fair 

 equivalent. But the case is otherwise with the great. 



There can be no doubt, however, that if accounts are 

 given to the world of the lives of men like Bacon and 

 Newton, Shakespeare and Milton, Priestley, Davy, and 

 Faraday, such accounts should be carefully freed from all 

 that is false or misleading. It is bad enough to jjry into 

 the private lives of such men at all ; but certainly it is 

 much worse to sjsread untruths about their lives, even 

 though this be done through mere carelessness ; and it is 

 worse still if falsehoods are sjjread wilfully. 



We are glad, therefore, to see that the inqtiiries made by 

 the late Professor De Morgan into details of the life of 

 Newton have been at length published. For undoubtedly 

 the present work will serve to clear up certain points 

 which were left in doubt after the ptiblication of Sir 

 David Brewster's later and larger book on Nevyton. 



De Morgan devotes the greater part of this work to the 

 miitter of Liird Halifax and Newton's niece. The 

 enemies of Newton and even some who — like Voltaire — 

 were genuine admirers of his genius, adopted the belief 

 that Miss Barton was Lord Halifax's mistress. Sir 

 David Brewster and others who have simply sought to 

 clear Newton at all hazards, have endeavoured to show 



* "Newton: his Friend and his Niece." By the late Augustus 

 De Morgan. Edited by his Wife, and by his pupil, Arthur Cowper 

 Eauyard. London : KUiot .Stock, 



