694 KANSAS CITY REVIEW OF SCIENCE. 



earth revolves around the sun in a year, we have demonstrated the sun to be that 

 many times greater in mass than the earth. 



Proof. — How are we to be satisfied that this result is correct ? The distance 

 to the sun is known ; and the time of the revolution of the earth around it, which 

 is 31,558,149 seconds; we know the number of inches in its orbit, and of course 

 the number traversed in a second. Draw a tangent to the orbit of the earth, and 

 let the centre of the earth be at the point of tangency ; in one second it will be 

 1,171,751 inches away, but the centre will be. 11 65 of an inch nearer the sun than 

 the tangent is, showing that the world falls that far every second from where it 

 would have been had not solar gravity drawn it away from the tangent ; because, 

 if in whirling a stone the cord should break, the stone would fly away on a straight 

 line tangent to the circle in which it moved. But .1165 of an inch is the half of 

 .233, and 16 1-12 feet is half of 32 1-6 feet, the velocity attained by a falling 

 body on earth ; that is, the velocity acquired by a mass falling from a state of 

 rest is, during the first unit of time, equal to twice the space fallen through. 

 Hence it is seen that geometrical analysis of the orbit traversed by the earth 

 gives the same value, precisely, for solar attraction that is found by the more 

 elegant method of using the velocity, 386 inches, as an instrument of weighing. 

 We have simply deduced ratio of mass ; that is, call the weight of the earth one, 

 and that of the sun is 331,654. Now, if we can find how many pounds the earth 

 weighs, the weight of the sun, in pounds, can easily be computed. From most 

 delicate pendulum and other experiments, it is found that the mean density of the 

 whole earth is 5.66, that of water being one. A cubic foot of water weighs 62.- 

 594 pounhs ; hence, a cubic foot of the earth weighs 5.66 times as much, or 

 354.28 pounds. Find the cubic feet in the earth, multiply by this factor, and 

 that by the ratio of weight of the sun to that of the earth, and the product will 

 be the number of pounds of matter in the sun. 



New Windsor, III., February 1882. 



ASTRONOMICAL NOTES FOR MARCH, 1882. 



BY W. W. ALEXANDER, KANSAS CITY, MO. 



On the 20th at iih. A. M., it will enter Aries, pass the celestial equator and 

 Spring will commence. 



