THE REASON WHY. 175 



1 Ts not God in the height of the heaven? and behold the height of the stars, 

 how high they are ?" JOB xii. 



786. How can man measure the distances of the planets ? 



By making observations at different seasons of the year, when 

 the earth is in opposite positions in her orbit ; and ty recording, 

 by instruments constructed with the greatest nicety, the angle of 

 sight, at which the planetary body is viewed ; by noticing, also, 

 the various eclipses, and estimating how long the first light after. 

 an eclipse has ceased reaches the earth, it is possible to estimate 

 the distances of heavenly bodies, no matter how Jar in the depths 

 of the universe those orbs may be. 



787. What are the opinions founded upon estimates 

 respecting the magnitude of the sun ? 



The diameter of the sun is 770,800 geographical miles, or 112 

 times greater than the diameter of the earth ; its volume is 

 1,407,124 times that of the earth, and 600 limes greater than all the 

 planets together ; its mass is 359,551 times greater than the earth ; 

 and 738 times greater than that of all the planets. A single spot 

 seen upon its surface has been estimated to extend over 77,000 miles 

 fn diameter, and a cluster of spots have been estimated to include an 

 area of 3,780,000 miles. 



788. What is the weight of the earth { 



The earth has a circumference of 25,000 miles, and is estimated 

 to weigh 1,256,195,670,000,000,000,000,000 tons. 



789. What is the specific gravity of a body? 



It is its weight estimated relatively to the weights of other 

 bodies. 



790. What determines the force with which bodies fall to 

 the earth ? 



Generally speaking, their specific gravity, which is proportionate 

 to the density, or compactness of the atoms of which they are 

 composed. 



791. Why does a feather fall to the earth more gradually 

 than a shilling ? 



Because the specific gravity of the feather and of the shilling is 



