PEOGKESS IN ASTRONOMY. 143 



The metcoritic nature of the rings was sugg-ested by Clerk Maxwell 

 in 1857, and Keeler's demonstration of the truth of this view by means 

 of the spectroscope, a few j^ears ago, was brilliant in conception and 

 execution. 



But during the last half of the century the interest centered in Mars 

 has been graduall}' increasing. The drawings made during the oppo- 

 sition of 1862, when compared with those made by Beer and Madler 

 (1830-1810), made it perfectly clear that in this planet we had to deal 

 with one strangel}^ like our own in many respects. There were obvi- 

 ously land and water surfaces; the snow at the poles melted in the 

 summer time; clouds were seen forming from time to time, and the 

 changing tones of the water surfaces suggested fine and rough weather. 



Afterwards came the revelation of the hawk-eyed Schiaparelli, begin- 

 ning in the j'ear 1877, and his wonderful map of the planet's surface. 

 The land surfaces, instead of being unbroken, were cut up, as an Eng- 

 lish farm is cut up by hedges; straight lines of different breadths and 

 tints crossed the land surfaces in all directions, and at times some of 

 them appeared double. Schiaparelli naturally concluded that the}'^ 

 were rivers — water channels — and, being- an Italian, he used the appro- 

 priate word canalL This, unfortunately', as it turned out, was trans- 

 lated canals. Now canals are dug, ergo there were diggers. From 

 this the demonstration not of the habitabilit}'^, but of the actual habi- 

 tation, of Mars was a small step, and the best way of signaling to 

 newly found kinsmen across some 30,000,000 miles of space was 

 discussed. 



The world of science owes a debt of gratitude to Mr. Percival 

 Lowell for having taken out to the pure air and low latitude of Ari- 

 zona an 18-inch telescope for the sole purpose of accumulating facts 

 tending to throw light upon this newly raised question. This he did 

 in 1891. Schiaparelli has continued his magnificent observations 

 through each opposition when the planet is most favorably situated 

 for observation, and since 1896 Signor Cerulli, armed with a 15-inch 

 Cooke, in the fine climate of Italy, has joined in the inquiry, so that 

 facts are now being rapidly accumulated. It has been stated that 

 markings similar to the strange so-called "canals" on Mars are to be 

 seen on Mercury, Venus, and even on the satellites of Jupiter. Mr. 

 Percival Lowell does not hesitate to proclaim himself in favor of their 

 being due, in Mars, to an intelligent system of irrigation. Signor 

 Cerulli claims that wherever seen they are mere optical effects. We 

 may be well content to leave to the next century a general agreement 

 on this interesting subject. 



Finally, in our survey of our own system come comets and meteor 

 swarms. One of the most fruitful discoveries of the century, that 

 comets are meteor swarms, we owe to the genius of Schiaparelli, 



