96 THE WONDERFUL CENTURY. CHAP. xi. 



means of the large telescope with a 25-inch object glass, 

 then the largest in the world. These are remarkable in 

 being exceedingly small, and very close to the planet. 

 They are said to be only six or seven miles in diameter, 

 and the inner one is only about 5800 miles from the 

 centre, or 3800 from the surface, of the planet, around 

 which it revolves in less than eight hours; while the 

 outer one is about 14,500 miles away, and revolves in a 

 little more than thirty hours. 1 



Still more recently (in September, 1892), a fifth satel- 

 lite of Jupiter was discovered by means of the great Lick 

 telescope in California. This also is very small and very 

 close to the planet, being less than half the diameter, or 

 about 40,000 miles, from its surface. 



Another very remarkable discovery is that of a system 

 of symmetrical markings, covering a large part of the 

 surface of Mars. They consist of a series of triangles or 

 quadrilaterals bounded by straight lines, which are some- 

 times seen double, at other times single, or are even alto- 

 gether invisible. Another peculiar feature is, that 

 where these canals (as they are termed) intersect there is 

 always a black circular spot, very distinct, and unlike 

 any markings upon other parts of the surface. It is a 

 curious fact that the double canals sometimes enclose a 

 space of more than a hundred miles wide and several 



1 In Gulliver's Travels, published in 1726, Swift describes the 

 astronomers of Laputa as having " discovered two lesser stars, or 

 satellites, which revolve around Mars ; whereof the innermost is 

 distant from the centre of the primary planet exactly three of his 

 diameters, and the outermost five ; the former revolves in the space 

 of ten hours, and the latter in twenty-one and a half." This is 

 a wonderful anticipation, especially as to time of revolution, and if 

 we substitute " radii" for " diameters," the distances are also very 

 near. 



