554 



NATURE 



[April 13, 1893 



brings all the main facts to a focus, sifting and sorting 

 them and ultimately deriving the final results. In the 

 following few brief extracts we propose to give in the 

 author's own words some of the more important conclu- 

 sions to which the examination of the facts has led him, 

 and we will commence with the ruddy appearance that 

 the planet puts on, the cause of which has always been 

 and still is doubtful. Apropos of the suggestion that 

 there may be red and not necessarily green vegetation 

 on the surface of Mars, he says— 



" Pourquoi, dira-t-on, la vdgdtation de Mars ne serait- 

 elle pas verte ?" 



" Pourquoi le serait-elle ? rdpondrons-nous. La terre 

 ne peut pas etre considerde k aucun point de vue, comme 

 le type de I'univers." 



" D'ailleurs, la vegetation terrestre pourrait etre 

 rougeatre elle-meme, et elle I'a etc en majorite pendant 

 bien des siecles, les premiers vdgetaux terrestres ayant 

 ete des lycopodes, dont la couleur est d'un jaune roux 

 tout martien. La substance verte que donne aux vegd- 

 taux leur coloration, la chlorophylle, est composee de 

 deux elements, I'un vert, I'autre jaune. Ces deux elements 

 peuvent etre separes par des precedes chimiques. II 

 est done parfaitement scientifique d'admettre que, dans 

 des conditions differentes des conditions terrestres, la 

 chlorophylle jaune puisse seule exister, ou dominer, Sur 

 la terre, la propartion est de i pour loo. Ce peut etre 

 le contraire sur Mars." 



In a mo5t interesting chapter comparing the Martial 

 with the terrestrial seasons, many important points of 

 similarity and difference are indicated. While the seasons 

 of Mars are of nearly the same intensity as ours, yet the 

 respective " working powers," so to speak, last nearly 

 twice as long. The cold and hot seasons in the northern 

 hemisphere continues for 381 and 306 days respectively, 

 and it is this fact which explains the great difference be- 

 tween the two hemispheres. The polar caps, as with us, 

 vary with the seasons, but attain their maxima and 

 minima three to six months after the winter and summer 

 solstices respectively. The dimensions which they assume 

 cover in winter 45° to 50"^ in diameter, and become 

 reduced in summer to 4° or 5°. Just outside the polar 

 regions, " des chutes de neige ont ete observees dans les 

 regions temperees, et parfois meme jusqu'a I'equateur. On 

 a vu dans I'hemisphere boreal des trainees en spiral 

 venant du pole, indiquant des coufants atmospheriques 

 influencds par le mouvement de rotation de la planete. 

 La calotte polaire boreale parait centrde sur le pole. 

 L'Australe en est eloignee a 5°, 4 ou 340 kilometres, a la 

 longitude 30°, de sorte qu'aux epoques de minimum le pole 

 sud est entierement decouvert : la vier polaire est libre^ 



That actual changes have taken place on the planet's 

 surface, in spite of the numerous sources of errors to 

 which such delicate observations are liable, seems to 

 have been proved by the discussion of the material. In 

 speaking of these sources of errors he says, " Ces diverses 

 causes de variations apparentes dans les aspects des 

 configurations geographiques de Mars suffisent-elles pour 

 rendre compte de toutes les variations observdes ? " 



" Non." 



" Des changements reels ont lieu a la surface de la 

 planfete, changements qui n'ont rien d'analogue dans ce 

 qui passe a la surface de la terre." ..." Nous voulons 

 l^arler de celle de I'etendue des taches sombres regarddes 

 comme mers, lacs ou cours d'eau." 



NO. 1224, VOL. 47] 



The channels, the origin of which has been productive of 

 so many hypotheses, are, according to the author, " dus 

 a des fissures superficielles produites par les forces 

 gdologiques ou peut-ctre meme a la rectification des 

 anciens fleuves, par les habitants, ayant pour but la 

 repartition gdndral des eaux k la surface des continents." 

 With regard to their doubling, after an examination of 

 several hypotheses, he is led to look upon this fact as the 

 result of refraction, although he remarks that "notre 

 savoir est insuffisant," and " le connu n'est qu'une ile 

 minuscule au sein de I'ocean de I'inconnu." He says, 



" Quant aux'de'doublements, 11 est difficile d'admettre que 

 rdellement de nouveaux canaux se forment du jour au 

 lendemain, semblables et paralleles aux premiers : nous 

 prdferons imaginer qu'ils puissent etre dus soit aux brumes 

 dont nous avons parle', soit plutot a une double refraction 

 dans I'atmosphere martienne. Etant donnees les condi- 

 tions de temperature (la chaleur solaire traversant facile- 

 rnent Tatmosphere martienne pour echauffer le sol), 

 I'evaporation doit etre tres intense, et il doit y avoir 

 constamment, au-dessus de ces cours d'eau, une grande 

 quantite' de vapeur rapidement refroidie, qui peut donner 

 naissance a des phcnomenes de refraction speciaux." 



In the concluding chapter, giving us a resume of 

 the conditions of life at the planet's suiface, the author 

 sums up some of the main results. The world of Mars 

 " parait etre, comme le/emarquait ddja William Herschel, 

 de toutes les planetes de notre syst^me solaire, celle qui 

 ressemble le plus a la notre. Nous pouvons repeter 

 aujourd'hui, sur les habitants de Mars, ce que ce grand 

 observateur e'crivait,il-y-a plus d'un siecle,]e i" Ddcembre 

 1 783 : ' its inhabitants probably enjoy a situation in many 

 respects similar to ours.'" It is possible, he adds, that 

 this world may be peopled with beings analogous to our 

 own : a race superior and in a more advanced stage, for 

 the globe of Mars, M. Flammarion holds, is an older 

 member of the solar system than our own. 



Such, then, is a general sketch of the contents of this 

 handsome volume of 600 pages. A glance through it is 

 sufficient to show that no pains have been spared 

 either by the writer or by the publisher, which 

 might in any way add to its completeness ; while the 

 illustrations, which in such a work as this are of the 

 highest importance, have been scattered with a lavish 

 hand, and with all due regard to accuracy and purpose, 

 no less than 580 telescopic drawings and 23 maps 

 appearing. 



In such a collection of facts as we have here, only one 

 slight erratum has been observed, and this occurs on 

 page 287, where it is stated that M. (now Prof) Schur, 

 at the observatory of Breslau made some measurements 

 of the planet's diameter, while it should have been, " at 

 Strassburg with a Breslau heliometer." 



Throughout the work M. Flammarion has in every case 

 given full references, which greatly enhances its value, 

 while in the appendix several drawings made during the 

 opposition of 1892 are inserted. 



N ever before was the planet viewed with such keenness 

 by astronomers as was the case last year, and it is by these, 

 as well as by those that have never had such an oppor- 

 tunity, that this work will be found of absorbing interest ; 

 astronomical literature is considerably enriched by its 

 appearance. William J. S. Lockyer. 



