114 SCHIAPARELLI'S LATEST VIEWS REGARDING MARS. 



In this connection it may be that a brief chronological statement of 

 the more important facts and discoveries relating to Mars will not be 

 without interest. In compiling it I have been chiefly indebted to Flam- 

 marion's classic work, La Planete Mars, although other sources have 

 also been consulted. 



272 B. C. The first known observation of Mars is recorded in Ptol- 

 emy's Almagest. 



1010 A. D. The phases of Mars were discovered by Galileo. 



1059, The first sketch showing surface detail was made by Huy- 

 gens. He also suggested a rotation in twenty-four hours. 



1000. Cassini determined the rotation of Mars to take place in 

 twenty-tour hours and forty minutes. He also observed the polar caps, 

 and "he distinguished on the disk of Mars, near the terminator, a 

 white spot advancing into the dark portion, and representing, without 

 doubt, like those of the moon, a roughness or irregularity of the sur- 

 face." This latter statement is curious, but the effect was undoubtedly 

 due to irradiation, since his telescope was entirely inadequate to enable 

 him to observe such a delicate phenomenon. 



1777. With the exception of Huygens, Hooke, and possibly Maraldi, 

 no one succeeded in making recognizable sketches of the surface detail 

 upon Mars for over a century, until Sir William Ilerschel took the mat- 

 ter up in this year. 



1783. Sir William Ilerschel detected the variation of the size of the 

 polar snowcai)S with the seasons, measured the polar compression, and 

 determined the inclination of the axis of the planet to its orbit. 



1785-1802. Schroeter made an extended study of the planet. His 

 drawings are upon the whole rather better than those of Herschel. He 

 discovered, among other things, the very dark spots to which I have 

 referred in my publications as the Northern and Equatorial Seas. He, 

 however, supposed them to be clouds. 



1810. Beer and Maedler publislied the first map of the planet, assign- 

 ing latitudes and longitudes to the various markings. On this map are 

 indicated the first canals and the first of the small lakes, so many of 

 which have been discovered during the last few years. The canals are 

 Nectar and Agathoda^mon and portions of Hades and Tartarus. The 

 lake is Lacus Phcenicis. Their map is the first- satisfactory represen- 

 tation of the entire surface of the i>lanet. The only region which pre- 

 .vious observers had clearly distinguished was that in the vicinity of 

 tlie Syrtis Major. 



1858. Secchi made a careful study of the colors exhibited by the 

 planet. 



1802. Lockyer made the first series of really good sketches of the 

 planet, showing all the characteristic forms with which we are now so 

 familiar. His drawings, and also those of some of the other observers, 

 give the first indications of the appearance of the central branch in 

 the Y, so called by Secchi. 



