-A tig US I 4, 



1887] 



NATURE 



Z^Z 



with some of the many nebulous fragments which con- 

 tinued to be drawn towards it from unfathomed depths of 

 space. Most of these became incorporated with the sun, 

 but a certain proportion must have been intercepted by 

 the planets, which, in their forming state, as possessing 

 less mass and velocity, were more sensitive to such shocks 

 than when fully formed. Thus, the plane of the ecliptic 

 might have been altered, we are told, 1° by the impact 

 upon the inchoate earth of a body possessing i/iooo 

 its present mass. Facilities even greater were offered 

 for changing the elements of rotation ; that of the earth, 

 when of seventy times its actual radius, might even have 

 been stopped altogether, by collision, under specially 

 favourable circumstances, with a mass only 1/10600 the 

 terrestrial. 



But this method of explanation is radically unsatisfac- 

 tory. It suggests the Dens ex machind of an unskilled 

 dramatist, and cannot be admitted without protest into 

 scientific speculation. We have learned to regard 

 cometary impacts as the last resource of the distressed 

 cosmogonist. Such events are not impossible, but to 

 resort to them in difficulties is to throw up the game of 

 ordered inference. The conviction remains unalterable 

 that the results visible to us were brought about by means 

 less apparently fortuitous. Dr. Braun, for example, is 

 obliged to suppose not only that, before the separation of 

 the moon, the axis of the lunar-terrestrial nebula was 

 deviated, by extraneous agencies of the kind indicated, to 

 the extent of 5° from its original position of perpendicu- 

 larity to the plane of the ecliptic ; but that, subsequently 

 to the separation, further shocks continued the process 

 upon the earth alone until the inclination attained its 

 present value of 23^^ Still less admissibly, the solar 

 axis is assumed, after the formation of Venus, to have 

 been tilted 5° by a number of successive impacts. A 

 transcendent degree of improbability seems to be reached 

 by this conjecture. 



In the order of planetary production. Dr. Braun follows 

 Laplace. Neptune is his oldest planet. And the fact 

 that it revolves very nearly in the " invariable plane " of 

 the solar system is confirmatory of the view that it really 

 was the first body (instead of being the last, as M. Faye 

 supposes) to become severed from the primitive nebula, 

 the rotation of which is likely to have been conducted 

 in that plane (Wolf, Bull. Astronomique^ t. ii. p. 228). 

 Neptune alone, owing to the distinction of his retrograde 

 rotation, is allowed by our author to have been formed 

 by the detachment and eventual condensation of a 

 nebulous ring. But Prof. Kirkwood has raised an objec- 

 tion to this orthodox mode of genesis which applies with 

 especial force to the remotest planet. The coalescence 

 into a single globe of the fragments of a broken-up ring, 

 if it happened at all (which is uncertain) would, it appears, 

 have been an unconscionably slow process. Thus,' two 

 opposite portions cf a ring of the dimensions of Neptune's 

 orbit, could scarcely have come together in less than 

 150,000,000 years. It must be admitted that this is a 

 startling demand on the time-exchequer even of the 

 cosmos. 



Uranus is regarded by Dr. Braun as what Bacon called 

 a " limiting instance " between the annular and the nuclear 

 methods of generation. An abortive ring gave place to a 

 centre of condensation, the result (helped, perhaps, by 

 some well-aimed cometary shoves) being the indecisive 

 character of the Uranian rotation on an axis lying prone 

 in the plane of revolution. 



These, then, are the main outlines of the last and 

 newest cosmogony. While dissenting from some of its 

 conclusions, we readily admit that it is, in several ways, a 

 noteworthy effort. Its appearance may be said to mark 

 the definitive abandonment, by sound thinkers, of the 

 annular method of planet and satellite fonnation. The 

 preciseness of the conditions of that celebrated hypothesis 

 lent it its charm, but has proved its ruin. Had they been 



less definite, it might have lived longer. But it gave, as it 

 were, hostages to the future which it has not been able to 

 redeem. 



It is gradually becoming clear that, while the various 

 members of the solar family owned unquestionably a 

 common origin, they can scarcely be said to have had a 

 common history. Each ran through a cycle of develop- 

 ment particular to itself, and appointed, without doubt, 

 to adapt it to a special purpose. The biography of the 

 earth and moon, as narrated by Prof Darwin, is an ex- 

 ample. Here influences predominated which, in every 

 other secondary system, were comparatively unfelt. 



This growing persuasion of what we may call planetary 

 individuality is reflected in Dr. Braun's vigorous and 

 original chapters. He has honestly, and with no small 

 ability, worked out ab initio the problems that they deal 

 with, and he finds them insoluble by the uniformitarian 

 method of treatment. The expedients by which he seeks 

 to obtain a diversity of results by introducing a diversity 

 of vicissitudes, strike us perhaps as arbitrary and awk- 

 ward ; but the admission of their necessity by an inquirer 

 of such acuteness, and so well abreast of contemporary 

 scientific thought, is highly instructive. We shall return 

 hter to the part of his interesting work devoted to solar 

 theory. A. M. Clerke. 



NOTES. 



On Tuesday Lord Hartington introduced to Sir W. Hart 

 Dyke a deputation consisting of Sir Henry Roscoe, Sir Lyon 

 Piayfair, Mr. Rathbone, Mr. G. Howell, Mr. Cyril Flower, Sir 

 B. Samuelson, and other gentlemen interested in education. 

 They urged the desirability of the Technical Education Bill 

 being passed, and of certain changes being made in the measure. 

 Sir W. Hart Dyke replied favourably on both points. He was 

 of opinion that the prospects of the Bill were good, both in the 

 House of Commons and in the House of Lords. 



The list of foreign men of science who have accepted the 

 invitation of the Local Committee to attend the Manchester 

 meeting of the British Association is steadily increasing, and 

 now numbers considerably over a hundred. Amongst those 

 whose names have been received since the list we published on 

 July 7, we note Prof. Cremona, of Rome ; Dr. Neumayer, 

 Director of the Hamburg Marine Observatory ; H. A. Rowland, 

 Baltimore ; Dr. Werner Siemens, of Berlin ; Prof. Horstman, 

 Heidelberg ; Prof. L. Weber, Breslau ; Prof. Capellini, 

 Bologna ; Prof. Carvill Lewis, Philadelphia ; Prof O. Blitschli, 

 Heidelberg ; Prof Camoy, Louvain ; Prof Erb, Heidelberg ; 

 Dr. Treub, Director of the Botanic Gardens, Java ; Capt. 

 Coquilhat, Brussels ; Dr. Godefroi, 's Hertogenbosch ; Dr. 

 Ludwig Wolf, Leipzig ; Signor Bonghi, the late Italian Minister 

 of Education ; Signor Luzzati, Rome ; Dr. E. Atkinson, 

 Director of the Massachusetts Bureau of Statistics ; and Dr. G. 

 Boissevain, Amsterdam. The King of the Belgians has inti- 

 mated his intention of nominating two representatives of the 

 Congo Free State to attend the meeting, and of these General 

 Strauch, Administrator- General of the Congo Free State, is ex- 

 pected to be one. A correspondent in Paris writes to us that the 

 Emperor of Brazil, who has lately spent some.time in the French 

 capital, will probably attend the meeting of the Association. 



Mr. a. T. Atchison, Secretary of the British Association, 

 is authorized to state that at the Manchester meeting space will 

 be provided in the galleries of the Reception Room for the ex- 

 hibition of specimens and instruments shown in connexion with 

 and in illustration of papers read in the Sections. To secure 

 admission a brief description of the specimens or instruments 

 must be submitted to the Local Secretaries not later than 

 August 10, together with a statement of the dimensions of the 

 table or other fixture required. No motor power will be avail- 

 able. The objects must be exhibited at the risk of the owners ; 



