DESCRIPTIVE ASTRONOMY. 



129 



year ? 



IVliat distance does the moon gain in her orbit each 



(See Astronomy, notes, pp. 89, 302.) 



75. State the general argument which renders it prob- 

 able that other worlds are inhabited. 



(See Astronomy, p. 63; also, note, p. 297.) 



74. Illustrate the uniformity of Nature. What thought 

 does this suggest ? 



(See Astronomy, p. 55; also, note, p. 297.) 



So far as we can judge, the laws of Nature, the properties 

 of matter, etc., are uniform throughout the universe, and re- 

 veal the workmanship of one Creator. 



75. At ^vhat rate are we traveling througJi space? 

 How is this determined ? 



The mean orbital velocity of the earth is 18.4 miles per 

 second. Knowing the circumference of its yearly path, the rate 

 of motion is easily calculated. 



76. Why does the length of a degree of latitude increase 

 in going from the equator toward either pole of the earth ? 



Because the form of the earth is not perfectly spherical, but 

 is flattened at the poles and bulged at the equator. 



LENGTH OF DEGREE OF LATITUDE. 



