894 Transactions of the American Institute. 



with regard to the stars than with regard to the sun. That produces 

 the difference between sidereal and solar time. 



The President — The idea is presented by Mr. Parker, that the 

 revolution of the earth around the sun is exactly measured by the 

 revolution of the moon around the earth. It is now generally admitted 

 that the celestial space is filled by an ether, which does not revolve in 

 connection with the earth and moon. The earth and moon do not 

 revolve in the same plane. The number of days in the year is now 

 thought to be attributable to a very different cause. Prof. Kirkwood, 

 of Indiana, a number of years ago, announced the law, dependent upon 

 the nebular hypothesis, that the square of the number of days in any 

 planet's year is in proportion to the cube of the attracting sphere of 

 that planet. 



Dr. P. H. Yan der Weyde — I wish Mr. Parker would apply his rule 

 to the moons of other planets. Fighting against the idea of a primi- 

 tive impulse, is only fighting against a windmill. Nobody believes 

 in that theory now. I consider the agreement merely accidental, 

 except so far as the figures or the mode of calculation are changed to 

 make the results agree. I see that Mr. Parker adds together the 365 

 revolutions of the earth on its axis, and the twelve revolutions of the 

 moon around the earth. He might just as well add six trees and three 

 dollars. It makes nine what ? Neither trees nor dollars. As to what 

 he calls precession, it is merely the acceleration of the stars ; and no 

 one pretends that it has anything to do with keeping the earth in 

 motion. 



Dr. J. V. C. Smith — I am inclined to think that this subject has 

 been treated in too curt a manner. The gentleman has read to us a 

 paper which is profound. He has bestowed great thought upon it. 

 He has made a demonstration by figures of what lie has stated. I 

 like the idea that the sun is going before and dragging this great train 

 with it. If the gentleman is wrong in his ideas, I think a paper 

 ought to be written to refute them. 



Mr. Parker — As to the agreement being a mere accident, I wish to 

 say that you may alter the proportions, and the same principle will 

 hold true. 



Dr. L. Bradley — Which of the satellites of Saturn will the principle 

 apply to ? It cannot apply to them all. 



Mr. Parker — That is not a subject I have treated of. My whole 

 time is devoted to business ; but I believe that when any one discov- 

 ers anything which is an addition to the knowledge of the world, it 

 is his duty to make it known. 



