N0VKMF!<?R, 1903 ] 



KNOWLEDGE. 



249 



ajjpearance of Pig. 5, which summarizes our solid know- 

 ledge of the Marfiau surface, may be conjured, by fixity of 

 gaze, into Fig. 6, or into a subjective breakdown of the 



Fig. 5. — Au Elementary View of our Eeal Knowlediie of Ita 



Fig. 6. — An Elementary Tiew of our .Vpparent Knowledge of 

 Mars. 



Illustrating the Action of Contrast in generating " Canaliform " 

 Sensations, as well as in decomposing the Tints of the Shadings, and 

 thus probably paving the way for the Duplication of the Markings; 



colour of all spots, as well as into a system of siagle-and- 

 double canals. It would perhaps be imprudent to affirm 

 at present that in contrast we have the sole and sufficient 

 e.\planation of gemination. Bat what is at any rate 

 certain is that it offers a very simple interpretation of at 

 least a great many cases of doubling ; and that the writer 

 fails to see any fatal objection to it. Nor can we reasonably 

 overlook the fact that whenever gemination has been 

 playing havoc with the " canals " and " lakes," the 

 phenomena of contrast have also been plainly evident in 

 the appearances presented by the planet. 



We are insensibly being brought to a standstill, and 

 future enquiry on Mars must rather direct its efforts to 

 the differentiation between subjei;tive and objective in the 

 known details, than in the discovery of novel complications 

 and further developments in the " canal " system. By 

 a singidar fatality, the observations made with ordinary 

 appliances in the smoky and troubled atmospheres of 

 English towns have always equalled, and often excelled, 

 those obtained with giant telescopes in the stillness of 

 elevated deserts. iJefinitiou does not, therefore, improve 

 in a direct ratio with an increase of height above the sea 

 level, whilst an excess of instrumental power has itself 

 proved jsowerless to reveal new features on a medal lying 

 at the bottom of a shallow stream. 



THE CANALS OF MARS. 



By K. Walter M.vundkr, k.e.a.s. 



Just a year ago a very interesting paper under the above 

 heading by Mr. B. W. Lane appeared in Knowledge; in 

 which he described a series of experiments tending to 

 show that " the mere shaj^e of the oceans of JMars is suffi- 

 cient to give rise to the appearance of the complicated 

 system discovered by Schiapurelli."* Mr. Liine's paper 

 led to Mr. J. E. Evans, headmaster of the Royal Hospital 

 School, Crrecnwicli, and myself, undertaking together a 

 scries of experiments with boys in that school, from which 

 some interesting results have been obtained. At the time 



• KxowLKDOE, 190?, November, p. 



when Mr. Lane's ])aper was published only a small pro- 

 portion of these experiments had been carried out, and I 

 was not therefore able to sjjeak as definitely as I now can 

 as to the conclusions to be drawn from them. These 

 experiments were supplemented k>y others, made chiefly by 

 Mrs. Maunder and myself, on the impressions produced l)y 

 lines and dots when near the limit of vision, which further 

 illustrate the subject. 



The experiments at the Eoyal Hospital School were 

 made in the following manner ; — A class of about twenty 

 boys, from twelve to fourteen years of age, were seated in 

 four or five rows at different distances from a carefully- 

 lighted diagram, which they were told to copy. The 

 diagram was reproduced from some published drawing of 

 Mars, but in nearly every experiment the canals were 

 omitted. For the most part any boy was used in only one 

 experiment ; but a few were set to draw the same diagram 

 twice, the second time at a different distance from the first. 

 The diagram was generally about six inches in diameter, 

 and the distances of the boys from the diagram ranged 

 from fifteen to forty feet, except in two exj^eriments 

 where the range extended up to sixty feet. 



One set of experiments is illusti*ated in the accom- 

 panying diagrams. Taking as basis Plate VIII. in Mr. 

 Lowell's " Marg," showing the Mare Sirenum and the 

 region north of it, we arranged three variations on it, on 

 a scale of about six inches, and submitted them to three 

 different sets of boys. The first variant (Fig. ]), showed 

 chiefly the "oases"; the second (Fig. 3), only the 

 "canals"; the third (Pig. 5), neither "oases" nor 

 " canals," but irregular lines. The results of an experi- 

 ment with the region of the Syrtis Major as subject are 

 illustrated in the Monthli/ Notices of the Eoyal Astro- 

 nomical Society, for June, 1903, Plates 18 and 19. 



The general result was striking. In several of these 

 experiments nearly all the boys drew " canals " on their 

 copies, though there were none on the original from which 

 they were copying. And these " canals "' were not placed 

 at random ; they were just in the very places where canals 

 are seen in the charts of Schiaparelii and Lowell The 

 boys agreed on the whole rather better in reproducing the 

 position and direction of canals like Phison, Hiddekel, 

 Euphrates, and Arnon, which were not on the original 

 before them, than in reproducing the position and outlines 

 of large and prominent markings like the Syrtis Major 

 and Sinus SabsBus, which were very distinctly on the 

 original. 



But in no single case, out of considerably more than 

 two hundred drawings, did we find a " canal '" drawn, 

 which seemed to owe its origin entirely to the shape of 

 the neighbouring " oceans," or dark markings. When- 

 ever the bright r.>gious, the " continents," in the diagram, 

 were left absolutelj' free from detail of any kind, then the 

 copyists all, without exception, left it free also. We bad 

 not a single instance which could be taken as confirming 

 Mr. Lane's result ; at least in the form in which he has 

 expressed it. 



This result must be talcen as negative only ; we have no 

 reason to assert that our experiments have dis2)roved Mr. 

 Lane's, only that they have not confirmed thorn. And au 

 explanation of this ditTtMvnce in our re^;ults can be readilv 

 suggested. Mr. Evans and myself felt t'lat the whole 

 value of our experiments rested in the boys being left 

 absolutely free from any suggestion, direct or indirect, 

 that would lead them to suspect tliat there was something 

 peculiar in the diagram which wi' wished theui to see. We 

 could not, therefore, press them to keep on staring at their 

 model after they thought they had copied all there was to see. 

 They did not strain iheir eyesight therefore, and so did 

 not receive any of the impressions which strained evesight 



