408 



SCIENCE 



[N. S. Vol. XXXII. No. 821 



in any astronomical journal, either in full or 

 in abstract, by Messrs. Lowell and Slipber; 

 nor have I seen reviews of these articles by 

 others. 



When I was photographing the spectrum of 

 Mars in December, 1896, with the high dis- 

 persion of a Rowland grating, fourth order, 

 14,438 lines per inch, as described in the Astro- 

 physical Journal, volume 5, page 236, 1897, I 

 realized that the Doppler-Fizeau principle 

 offers great advantages for solving certain 

 questions of the Martian atmosphere, as the 

 water vapor and oxygen lines introduced in 

 the Martian spectrum by the earth's atmos- 

 phere would be displaced with reference to 

 corresponding lines in the Martian spectrum; 

 but that the method could not be applied, with 

 Tiigh dispersion, as the critical lines are all 

 sitviated in the red, orange and lower yellow, 

 for which regions sensitive plates were not 

 then available. The isochromatic plates of 

 that date gave under-exposed images. How- 

 ever, the question of applying the method by 

 means of the three-prism spectrograph, which 

 had then been in successful use for nearly a 

 year, was thoroughly investigated to deter- 

 mine whether the dispersion of the three- 

 prism instrument, when adjusted for the 

 orange region, would be sufficient to separate 

 or broaden appreciably the Martian and tel- 

 luric lines when Mars was near quadrature in 

 the first half of 1897. It was found that the 

 dispersion was too low to afford any hope of 

 success, and as the comparatively insensitive 

 dry plates would not admit of higher disper- 

 sion, the subject was temporarily dismissed. 



I find that Dr. Slipher's observations were 

 first attempted in 1902-03, not published till 

 August, 1906, and again early in 1905 ; but 

 as his telescope had a smaller light collecting 

 power and his spectrograph apparently a lower 

 •dispersion than I had considered using in 

 1897, his efforts failed. Here is his conclu- 

 sion : " Measures were made, but they were 

 difficult, uncertain and discordant, and 

 neither proved nor disproved the displace- 

 ment." 



I note that while Professor Lowell recog- 

 mized the existence of the method of solution 



in October, 1902, as stated in his bulletin, he 

 appears to have published nothing until Au- 

 gust, 1905. 



Appropriate notes will be published in the 

 Lick Observatory Bulletins calling attention 

 to Professor Lowell's and Dr. Slipher's ar- 

 ticles, as well as to Dr. Slipher's results in low 

 dispersion photography of the Martian and 

 lunar spectra obtained in the summer of 1905, 

 which led him to the conclusion : " No bands 

 or lines could be seen in Mars that were not 

 in the moon, nor any that were certainly 

 stronger in the planet than in the moon. In 

 short, the spectrum of Mars appeared the same 

 as that of our equally high moon, so far as 

 selective absorption is concerned." 



W. W. Campbell 



Mt. Hamilton, 

 August 15, 1910 



QUOTATIONS 



THE SHEFFIELD MEETING OF THE BRITISH 

 ASSOCIATION 



Huxley, in one of the last of his addresses, 

 expressed some apprehension lest science 

 should be crushed by the weight of the very 

 gifts which she had demanded with such in- 

 sistence from nature. The same thought has 

 been present to many minds during the Shef- 

 field meeting of the British Association, al- 

 though it may not have been formulated with 

 any preciseness. There was a time, not so 

 many years ago, when men of science could 

 aspire to the possession of an all-round ac- 

 quaintance with many, if not all, departments 

 of natural history, as it was then called. That 

 time has gone by, and the infinite specializa- 

 tion which is a leading characteristic of 

 science to-day is becoming more and more 

 embarrassing to those engaged in the advance- 

 ment of knowledge. This may be one of the 

 causes of the comparative paucity of the num- 

 bers attending the Sheffield meeting. At first 

 it seemed as if the members and associates 

 would fall short of the number which took 

 part in the previous meeting at Sheffield 

 thirty-one years ago. Happily, this has not 

 proved to be the case. There have been 1,449 

 members and associates this year, as compared 



