OCTOUEK 29, 1896] 



NA TURE 



627 



tion were visible when I first looked at it in August. . . . 

 By moments of better seeing its two sides showed darker 

 than its middle ; that is, it was already double in embryo, 

 with a dusky middle-ground between the twin lines. In 

 October the doubling had sensibly progressed . . . the 

 ground between the twin lines had grown lighter. By 

 November the doubling was unmistakable." 



Let us nowturn again to the canals, and see what explana- 

 tion Mr. Lowell gives to account for their origin and sub- 

 sequent duplication. The idea he adopts is one that has 

 already been suggested by Schiaparelli and Pickering, 

 namely vegetation. The water in its passage from the 

 pole tills a canal, and thus irrigates the country on both 

 sides for agricultural pursuits. The actual canals them- 

 selves we do not see : but at a later period the vegetation 

 raised thereby becomes apparent, which gives us the 

 visible canals. The darker lines which cross the dark 

 markings, or the more permanent areas of vegetation, 

 represent also a more advanced growth of vegetation, 

 caused by the supply of water, which passes on its 

 journey to fill those in the brighter regions. Observation 

 at Flagstaff has shown that " there is no canal in the 

 dark areas which does not connect with one in the 

 brighter regions." 



So much, then, for the canals and their origin ; but 

 how about their apparent duplication ? Mr. Lowell, 

 however, has little to say on this point. 



" E.\actly what takes place ... I cannot pretend 

 to say. It has been suggested that a progressive ripen- 

 ing of vegetation from the centre to the edges might 

 cause a broad swath of green to become seemingly 

 two. There are facts, however, that do not tally with this 

 view." 



From the abo\e e.xtract, it will be seen that Mr. Lowell 

 does not like to commit himself to any statement in ex- 

 planation of this phenomenon — at any rate, not at present. 

 There seems, however, many i-easons to believe that if 

 the canals be due to vegetation, then their doubling is 

 most probably the results also of vegetation ; how this 

 comes about is, however, still a moot point. 



One of the best instances we have on the earth, of a 

 large strip of land being fertilised once a year directly 

 by an inundation of a large river, is that of the Nile 

 valley. In following, however, the phases which the 

 country on each side of her banks undergoes at the time 

 of and after the flood, it is difficult to account for the 

 development of the duplicity as observed on the Martian 

 disc. Perhaps the irrigation scheme on the surface of 

 Mars has been carried to such an e.xtreme degree of 

 development, that smaller parallel canals on each side of, 

 and some distance from, the larger ones have been con- 

 structed so as to become filled and eventually cut off 

 from the main canal when the water commences to recede. 

 In this way the land would be best fertilised at first on 

 the banks of the main canal, but at a later date on those 

 of the smaller canals. The appearance of a canal should 

 then begin by being single ; as time went on it should 

 broaden, and eventually become double, the two most 

 fertilised strips being parallel, but at some distance from 

 the main canal. The connecting channels between the 

 iiiain and lateral canals, or rather, the vegetation along 

 these lines, would most probably be invisible on account 

 •of their extreme shortness. 



Such an explanation as this overcomes the difficulty 

 that there are some canals that do not appear double. 

 One has only to assume that the side canals in these 

 cases have not yet been constructed, and duplicity is on 

 this hypothesis impossible. Whatever the real explanation 

 may be, it is certain that greater attention must be paid 

 to the actual development and fading, before this 

 problem can be looked upon as really solved. 



In conclusion, we cannot help remarking on the very 

 logical handling of the subject in this volume. The 

 author makes out, further, a very good case for the 



NO. 1409, VOL. 54] 



hypothesis of " vegetation," which will be hard to op- 

 pose. It does seem, however, rather premature for him 

 to draw such decided conclusions from this, his first 

 large series of observations ; but his own words show 

 that even these views may be considerably changed by 

 future observation, and he has not, therefore, tied himself 

 too fast to them. In the chapter on the germination of 

 the canals, he remarks that " perhaps we may learn con- 

 siderably more about it at the next opposition. .A.t this 

 the tendril end of our knowledge of our neighbour we 

 cannot expect hard wood." 



The observations of Mr. Lowell have, nevertheless, 

 added greatly to our knowledge of the surface-markings 

 on this planet, and astronomical science owes him a debt 

 of gratitude for the energy he has displayed in fitting 

 out and conducting this expedition, that has been re- 

 warded with such interesting and valuable results. 



The book itself not only appeals to professional astro- 

 nomers, but should be read by all those interested in 

 observations of Mars, for it is written in language that 

 will be found comprehensible even to the uninitiated. 

 The illustrations, which are numerous, are by no means 

 lacking in quality, and considerably enhance the value of 

 the book. 



Wn,I,I.\M J. S. LOCKYER. 



THE SCIENTIFIC DEPARTMENT OF THE 

 IMPERIAL INSTITUTE. 



THE extended organisation of the experimental branch 

 of the Scientific and Technical Research Depart- 

 ment of the Imperial Institute is now nearly complete, 

 and the whole of the west corridor of the second floor is 

 occupied by well-equipped laboratories, instrument rooms, 

 and sample examination rooms, whilst the recently ap- 

 pointed staff of skilled chemists is already engaged in 

 the scientific and technical investigation of numerous 

 Indian and Colonial products, which are likely to prove 

 of commercial importance or of scientific interest. 



The winter course of lectures will be opened on Monday, 

 November 9, at 8.30 p.m. with a discourse by Prof 

 VVyndham Dunstan, F.R.S., the recently appointed 

 Director of the Scientific Department, the subject of 

 which will be '■ Illustrations of some of the work of the 

 Scientific and Technical Research Department of the 

 Imperial Institute." After the lecture the research 

 laboratories of the department will be open for the 

 inspection of visitors, and a number of interesting 

 exhibits will be on view. 



On November 16, .Mr. William Crookes, F.R.S., will 

 deliver the first of two illustrated lectures on the 

 " Diamond Fields of Kimberley," in connection with 

 which a number of specimens and experiments of great 

 interest will be shown. Among other topics Mr. Crookes 

 will discuss the nature and probable origin of the dia- 

 mond, and will give an account of recent researches of 

 his own. On the occasion of the first lecture, Lord Loch 

 will preside. 



On the two remaining Monday evenings in November, 

 illustrated lectures will be given by Prof J. W. Judd, 

 C.B., F.R.S., the Dean of the Royal College of Science, 

 on " Rubies, Natural and Artificial, with special reference 

 to then- Occurrence in the British Empire" (November 

 23), and by Dr. J. H. Bryan, F.R.S.,on " Flight, natural 

 and artificial" (November 30). 



Succeeding lectures, the dates of which will be duly 

 announced, will be given by Prof .\. H. Church, F.R.S., 

 Professor of Chemistry to the Royal Academy, on "Some 

 Food-grains of India" ; by Dr. Schlich, CLE., of the 

 Royal Indian Engineering College, Cooper's Hill, on 

 " The Timber Supply of the British Empire " ; by the 

 Hon. W. Pember Reeves, Agent-General for New Zea- 

 land, on "The Hot Springs District of New Zealand"; 



