234 LOWELL — AREOGRAPHY. [April 4, 



14. The history of areography may be thus summed up : 



1 840-1 8 76. Period of detection of large dark and light markings 



on the surface of the planet. 

 1877-1892. Period of detection of *' canals" in the bright 



regions. 

 1892-1902. Period of detection of '* canals " in the dark areas. 



15. Three deductions follow an inspection of the whole series of 

 maps : 



I. The fundamental agreement of the series. 

 This is evident at once, but can perhaps be made more so by 

 placing the later maps at a greater distance from the eye, upon 

 which the fainter markings take on the look they would wear were 

 the planet less well seen. 



16. II. Evidence that the regularity of the '^canals" was not 

 due to predisposition on Schiaparelli's part, but was forced upon 

 him by the objects themselves. 



Comparing his own maps on the subject, it appears that an evo- 

 lution took place in his perceptions. His first map, that of 1877, 

 represents the '^ canals " as straits, more or less irregular, running 

 up into the land. His next, made in 1879, depicts them narrower, 

 straighter and decidedly more peculiar. That of 1881-82 shows 

 them as fully developed geometrical designs, a character they never 

 afterward lose. 



Now, the fact that his representations of the canals grew in regu- 

 larity as time went on, proves such character to have been no im- 

 putation on his part. Had he imagined it, he would have depicted 

 the canals so to start with. As it was, increasing familiarity com- 

 pelled him to recognize features which he had at first consciously 

 or unconsciously ignored. We have here, indeed, a record left by 

 himself of his own conversion to belief in the very qualities that 

 make the canals so difficult of credence. 



17. III. Evidence of an evolution in the detection of the mark- 

 ings from simple to complex. A steady progression in the matter 

 of detail can be traced from its beginning to its end. And the 

 progression is in increasing order of difficulty. The large dark 

 patches are the easiest of detection, the Schiaparellian *^ canals" 

 in the bright regions the next so, the '^ canals " in the dark regions 

 the hardest. This is conclusively shown by the number of times 

 each class was seen in the many drawings made at Flagstaff. It is 

 here also evidenced by the way each map, while adding to, also 

 corroborates its predecessor. 



