236 



SCIENCE. 



[N. S. Vol. IV. No. 86. 



feet indiflference. Because they are straight 

 and radiate from a center, did they have an in- 

 telligent personal origin ? 



Is a seasonal change on Mars evidence of an 

 intelligent population ? The virgin forests and 

 prairies of America donned and doffed their an- 

 nual green suit even better before the advent of 

 man than to-day. 



The organic origin of the dark areas on Mars 

 has great advantages, as Schiaparelli said; but 

 the addition of intelligent beings to the hypoth- 

 esis adds to, rather than removes, the diflS- 

 culties, and leads to pure speculation. If we 

 attempt an explanation of the irrigation system 

 we can, in our dilemma, only say that the Mar- 

 tians are more intelligent than we are! 



The most striking feature of the Flagstaff 

 observations relates to the detection of a large 

 number of canals and ' oases. ' It is a question 

 how far these observations have had confirma- 

 tion, and how far they need it. The observa- 

 tion of 44 canals in the dark areas by Mr. 

 Douglass confirms Prof. Schaeberle's 1892 obser- 

 vations, but they were evidently not seen by 

 Messrs. Lowell and Pickering. Mr. Lowell 

 gives a long list of canals in the bright areas, 

 but it is uncertain whether or not they were 

 seen by more than one observer. His list con- 

 tains nine canals that were seen on only one 

 occasion; they are drawn on the final map and 

 given names. His list contains one canal that 

 was not seen at all, but on one occasion was sus- 

 pected', it is put on the map and given a name. 



Mr. Lowell accepts the line of reasoning put 

 forth by Proctor and others as to the extent of 

 Mars' atmosphere, viz. : That the mass of ter- 

 restrial atmosphere is to the mass of Mars' at- 

 mosphere as the mass of the Earth is to the 

 mass of Mars ; which leads to the result that 

 the density of the atmosphere at the surface of ' 

 Mars is about half the density of our atmos- 

 phere at the summit of the Himalayas. This 

 is in complete harmony with the Lick spectro- 

 scopic results of 1894, which pointed to that 

 density as the maximum limit, but is quite out 

 of harmony with the earlier spectroscopic re- 

 sults. 



It is well known that the atmosphere of Mars 

 is practically cloudless. There is some evi- 

 dence of clouds near the terminator (sunrise 



and sunset line), and some in favor of occa- 

 sional small clouds over the portions fally ex- 

 posed to the sun's light and heat. For two or 

 three weeks in October, 1894, all the surface fea- 

 tures were partially obscured and rendered in- 

 distinct, as if by general haziness, after which 

 they again became distinct. Mr. Lowell be- 

 lieves that the Flagstaff observers saw several 

 hundred clouds near the terminator, though he 

 makes no use of them in explaining Mars' hy- 

 drographic system. They are not needed for 

 irrigation purposes. The atmosphere is sup- 

 posed to be very rarefied, the polar snows melt, 

 the water in some manner evaporates into the 

 atmosphere to form the polar caps by precipita- 

 tion the following winter. If snow is precipi- 

 tated at the cold poles, why should not rain be 

 precipitated in the warmer regions ? If the at- 

 mosphere is thin and takes up the evaporated 

 water in a clear noon sky, why should not the 

 rarefied atmosphere cool rapidly at night and 

 rain be precipitated, especially in the valleys? 

 If the atmospheric circulation is slow, as it is 

 supposed to be, the visible effects of night rains 

 could well progress from the poles toward the 

 equator, through the valleys, and a delicate 

 system of surface levels would not have to be 

 provided. This is not put forth as a theory of 

 the canal system, except to emphasize the fact 

 that we should give Nature a chance to do 

 this work before we resort to artificial irriga- 

 tion. 



In 1890 there began at Mount Hamilton a 

 new class of observations on Mars, relating to 

 the bright projections on the terminator. Similar 

 observations were made in 1892 and 1894. 

 There is no doubt that they are very important, 

 and great stress was laid on them. There are 

 some arguments in favor of there being clouds, 

 but many more in favor of there being moun- 

 tains. The observed phenomena are fally ex- 

 plained by supposing a mountain chain to lie 

 across the terminator and to disappear from 

 sight by the planet's diurnal rotation. The ob- 

 served projections were such as would be 

 produced by the sun shining on the mountain 

 tops outside the terminator, and the observed 

 adjacent depressions were such as v/ould be 

 formed by the shadow of the mountain range 

 lying within the terminator. Concerning the 



