June 9, 1910J 



NATURE 



443 



--tion, and then appears the amendment, which is a 

 direct negative ; as an example one might cite the rota- 

 don periods of the inner planets ; but one that is nearer 

 ■ja the present question is the problem as to the spectro- 

 scopic evidence for the existence of water vapour in .Mars. 



Since Huggins compared the Martian and lunar spectra 

 in 1867, a number of observers have made similar observa- 

 tions under various conditions, and with contradictory 

 results. The summarised history of the research is given 

 by Prof. Campbell in a recent Bulletin (No. 169) from the 

 Lick Observatory, and the majority of the conclusions are 

 in favour of the presence of water-vapour bands ; whether 

 the conclusions were supported by the evidence, when 

 adequately analysed, is the question. Observations made at 

 Mount Hamilton in 1894 demonstrated to him that, to obtain 

 satisfactory evidence, they should be repeated at an altitude 

 sufficient to escape the greatest possible proportion of the 

 terrestrial atmospheric effects, and, to this end, he 

 examined the conditions obtaining on the summit of Mount 

 Whitney, the highest point in the United States, in 1908. 

 The preliminary survey satisfied Prof. Campbell as to the 

 atmospheric conditions, and he decided that, if the neces- 

 sary money could be obtained for shelters and equipment, 

 an expedition from the Lick Observatory should take 

 advantage of the favourable opposition of 1909 to carry the 



posed of hoar-frost, demanding a small quantity of vapour, 

 would probably not be out of harmon}' with his observa- 

 tions. In Bulletin No. 43 of the Lowell Observatory Mr. 

 Abbot's report is quoted to the effect that he and Prof. 

 Campbell were on Mount Whitney during unusually un- 

 favourable weather, under conditions which would probably 

 not be met with at that season one year in ten. This is 

 important, because, no matter how much of the theoretical 

 water-\apour content of the terrestrial atmosphere was left 

 below, it is absolute evidence that water vapour was 

 present, in quantity, above. 



The Mount Whitney plates, at the most, only afford 

 negative evidence, and it is not contended that they do 

 more. Thus the question of water vapour becomes one of 

 amount rather than of existence or non-existence, and its 

 settlement is rather academic than practical. There is no 

 doubt as to the difficulty of securing absolute evidence — 

 so many variables have to be eliminated before the sought- 

 for residual is attained. 



But, as stated above, the question is now generally 

 accepted as settled in favour of the presence of water 

 vapour in the Martian atmosphere. The darker edge of 

 the melting " snow " caps, the proved existence of clouds, 

 and the changes of intensity and shape of many features, 

 point definitely to the existence of a fluid material, and, 

 without any violent assumptions, to 

 that fluid being water. We note that 

 Prof. Campbell suggests that the 

 observed yellowish colour of the clouds 

 may indicate for them some other 

 chemical compound than H.O, but, if 

 this is so, should not the spectrum of 

 Mars indicate some other absorption 

 which is not mentioned? 



William E. Rolstox. 



THE RESEARCH DEFEXCE 

 SOCIETY. 



Fig. 4. — Trmporary Observatory on Mrunt Whitney, for the investigation of water-vapour in the 



atmosphere of Mars. 



research a step further. As is usual in, and, one might 

 say, peculiar to, America, funds were forthcoming, with 

 the result that, at the end of August, 1909, the summit of 

 the mountain was occupied by an especially equipped 

 expedition ready to take spectrograms when the conditions 

 of Mars and the moon were favourable. 



Such spectrograms, six in number, were secured on the 

 nights of September i and 2, and it is to the discussion 

 of the evidence afforded by these that Bulletin No. 169 is 

 devoted. This evidence does not appear to be positively 

 conclusive, but Prof. Campbell deduces " that the quantity 

 of any water vapour existing in the equatorial atmosphere 

 of Mars at the time these observations were made was too 

 slight to be detected by present spectrographic methods. 

 • • • it is difficult to conceive that the quantity- of vapour 

 above unit area on Mars could exceed or equal the quantity 

 ?/.. .terrestrial vapour above the same area of Mount 

 *V hitney. ' ' 



It should be remarked here that the altitude of the 

 summit of Mount Whitney is 14,501 feet, and, according 

 to Hann's empirical formula, 079 of the terrestrial water 

 vapour would be below. A photograph of the shelter and 

 Pf ""^ of the equipment is reproduced, from, the Journal of 



p -^' Astronomical Society of Canada, in Fig. 4. 

 h \f ^^'"P^l' expressly states that it is not contended 

 that Mars has no water vapour, and that polar caps com- 

 NO. 2 119, VOL. 83! 



T^HE annual meeting of the Re- 

 ■*• search Defence Society* was held 

 on Friday, June 3, at the Royal 

 College of Physicians, and was ver>' 

 largely attended. The chair was 

 taken by the Earl of Cromer, presi- 

 dent of the society. The other 

 speakers were the Hon. Sydney 

 Holland, chairman of committee. Sir 

 Richard Douglas Powell, Sir David 

 Bruce, Mr. Anthony Hope Hawkins, 

 and Mrs. Scharlieb. The work and 

 the literature of the society are by 

 this time well known to the public, 

 and the annual report shows a great 

 increase in the membership and in the extent of the 

 work. 



Perhaps, of all the speeches, the most interesting was Sir 

 David Bruce 's account of his observations on the African 

 sleeping sickness and other African diseases. In 1903 it 

 had been hard or impossible to persuade the Uganda chiefs 

 that the sleeping sickness is carried by the tsetse-fly. "* But 

 these same so-called uncivilised natives, whose untutored 

 minds could not perhaps at once grasp the position, a few 

 years later were so convinced of the truth of what we told 

 them that they cleared the lake-shore and islands of their 

 inhabitants, with the result that, so far as I am aware, 

 at present not a single new case of sleeping sickness is 

 being contracted in Uganda proper, and the toll of human 

 lives to this plague has ceased to be paid. This toll has 

 been estimated at 200,000 out of a population of 300,000. 

 In one island alone, Buvuma, with a population of 32.000, 

 18,000 are reported to have perished." From this fact 

 Sir David Bruce went on to speak of experiments which 

 had shown how long the fly, once infective, may remain 

 infective, and of the question of the infectivity of animals. 

 Then he referred to a disease which destroys 70 to 80 per 

 cent, of the calves born in Uganda ; the cause and the 

 nature of tliis disease had been discovered by experiments 

 on animals. " By animal experimentation we found out 

 the nature of several of the most important diseases of the 



