A GLIMPSE THROUGH THE CORRIDORS OF TIME. 493 



the earth is much more than the primitive three hours, yet that of the 

 moon has increased to several times the rotation of the earth. 



The moon recedes still farther and farther, and at length a notice- 

 able epoch is reached, to which I must call attention. At that epoch 

 the moon is so far out that its revolution takes twenty-nine times as 

 long as the rotation of the earth. The month was then twenty-nine 

 times the day. The duration of the day was less than the pi'esent 

 twenty-four hours, but I do not believe it was very much less. The 

 time we are speaking of is not very remote, perhaps only a very few 

 million years ago. The month was then in the zenith of its glory. 

 The month was never twenty-nine times as long as the day before. It 

 has never been twenty-nine times as long as the day since. It will 

 never be twenty-nine times as long as the day again. 



Resuming our history, we find the moon still continuing to revolve 

 in an ever-widening circle, the length of the month and of the day 

 both increasing. The ratio of the day to the month was still under- 

 going a change. When the moon was a little farther off, the earth 

 only revolved twenty-eight times instead of twenty-nine times in one 

 revolution of the moon. Still, the velocity of the earth abates until it 

 only makes twenty-seven revolutions in one revolution of the moon. 

 This is an epoch of especial interest, for it is the present time. In the 

 present order of things the moon revolves round the earth once while 

 the earth rotates twenty-seven times. This has remained sensibly true 

 for thousands of years, and no doubt will remain sensibly true for 

 thousands of years to come, but it will not remain true indefinitely. 

 Wondrous as are the changes which have occurred in times past, not 

 less wondrous are the changes which are to occur in time to come. 

 The tides have guided our gropings into the past ; they will continue 

 to guide our researches to make a forecast of the future. 



Farther and farther will the moon retreat, and more and more 

 slowly will the earth revolve. But we shall not pause at intervening 

 stages ; we shall try to sketch the ultimate type to which our system 

 tends. In the dim future, many millions of years distant, the final 

 stage will be approached. As this stage draws nigh, the rotation of 

 the earth will again approach to equality with the revolution of the 

 moon. From the present month of twenty-seven days we shall pass 

 to a month of twenty-six days, of twenty-five days, and so on, until 

 eventually we shall reach a month of two days, and lastly a month of 

 one day. When this state has been attained the earth will constantly 

 turn the same region toward the moon. I do not know what is the 

 locality on the earth which is destined for this distinction. 



Here you see that the first state and the last state of the earth- 

 moon history are in one sense identical. In each case the same face of 

 the earth is constantly directed toward the moon. In another way, 

 how different are the first stage and the last ! At the beginning the 

 day and the month were both equal, and they were each three hours. 



