PHILOSOPHICAL SOCIETY OF WASHINGTON. 85 



was fresh, and there is abundant reason to believe it overflowed 

 its basin, sending its surplus to the ocean. 



This lake is referred to the Glacial epoch by reason of the fol- 

 lowing coincidence: Upon the slopes which exhibit its sediments 

 there are also gravels, brought down from the mountains bv run- 

 ning water and spread by the same without thorough sorting. A 

 small portion of tliese gravels overlie the lacustrine beds, but the 

 great mass underlies them. The sequence, gravel, marl, gravel, 

 shows that the lake epoch was transient, being preceded as well 

 as followed by a period when, as now, the climate was too arid 

 to maintain a broad water surface. It was a climatal episode 

 characterized by increased humidity, or lower temperature, or 

 both. The Glacial epoch was a climatal episode of the same 

 general character, and occurred in the same general geological 

 period — that immediately antecedent to modern time. There is 

 the same reason for supposing the two coincident in time, that 

 there is for correlating the European with the American Glacial 

 epoch. 



At that time the Atlantic slope and the region of the "Great 

 Basin" were contrasted in climate, just as now. The general 

 causes that covered the humid east w^ith a mantle of ice, sufficed 

 in the arid west only to flood the valleys with fresh water and 

 send a few ice streams down the highest mountain gorges. 



Prof. J. E, Eastman read a paper on 



THE FREQUENCY OP THE OCCURRENCE OF THE ZERO AND THE NINE 

 DIGITS IN THE TENTHS OF SECONDS AS OBTAINED FROM THE 

 CHRONOGRAPHIC RECORD OF TRANSIT OBSERVATIONS. 



(abstract.) 



A partial examination of the records of observations with the 

 Transit Circle at the Naval Observatory was made in 1870 in 

 order to determine whether, in reading the recorded transits from 

 the chronograph sheets, there was a tendency to record any par- 

 ticular figures in the ol)serving book. 



This examination tended to confirm my belief that no such 

 bias existed, but I was unable to complete the investigation until 

 the spring of 1873. 



In the latter investigation an equal number of records were 

 used from each of two different chronographs. On each chrono- 

 graph the clock closes the circuit each second. One which I 

 shall refer to as chronograph A, employs only one pen, and the 

 speed is regulated by a friction governor. The length of a sec- 

 ond's interval is 0.426 inch. The other chronograph, which I 

 shall call chronograph B, uses only one pen, and the length of 

 the second's interval is one-third of an inch. 



This instrument is known as the Hippe chronograph, the gov- 



