attraction of gravity on his surface is barely half that on the earth,
and a man would feel very light there. Mercury seems to have a dense
atmosphere, and probably high mountains, if not active volcanoes. The
sunshine is from four to nine times stronger there than on the earth,
and as summer and winter follow each other in six weeks, he is doubtless
rather warm.

"Venus, the 'Shepherd's Star,' and the brightest object in the heavens
after the moon, can sometimes be seen by day, and casts a distinct
shadow at night. She is about 67 million miles from the sun, revolves
round him in 225 days, and rotates on her axis in 23 to 24 hours, or as
Schiaparelli believes, in 224 days. Her diameter is 7,600 miles, and her
mass nearly five times that of an equal volume of water. Gravity is
rather less there than it is here. Like Mercury, she appears to have a
cloudy atmosphere, and very high mountains. On the whole she resembles
the earth, but is, perhaps, a younger as well as a warmer planet.

"The green ball, next to Venus, is, I need hardly say, our own dear
little world. Terra, or the earth, is 93 million miles from the sun,
goes round him in 365 days, and turns on her axis in 24 hours less four
minutes. Her diameter is 7,918 miles, and her density is 5.66 times that
of water. She is attended by a single satellite, the moon, which
revolves round her in 27.3 days, at a distance of 238,000 miles. The
moon rotates on her axis in about the same time, and hence we can only
see one side of her. She is 2,160 miles in diameter, but her mass is
only one-eightieth that of the earth. A pound weight on the moon would
scale six pounds on the earth. Having little or no atmosphere or water,
she is apparently a dead world.

"The red planet beyond the earth is Mars, who appears in the sky as a