446 THE POPULAR SCIENCE MONTHLY. 



5. Stratified gravels and sands with fossil shells of the oyster, also wood 

 and lignite underneath the bowlder-drift. 



6. Laminated sands and clays with decayed vegetation and lignite have been 

 found; also one shark's tooth (C. angustidens). 



7. The above beds seem to merge into more clayey sands, and in the deeper 

 portions tine dark-colored plastic clay. 



The period we have considered is one of immense duration, but 

 throughout there is no evidence of sudden or violent changes. No 

 catastrophe has " set Long Island off from the mainland." In its 

 wonderfully complex structure it is a monument of a state of things 

 which has passed away, but also of a series of movements of oscilla- 

 tion which has continued to the present time. 



But it is only after long periods of time that these become obvious, 

 and we realize how completely old landmarks have disappeared. 



The tourist in Italy lingers with astonishment before the erect 

 columns of the temple at Pozzuoli in the bay of Baise, and sees, at a 

 height of twenty feet above their base, proof of their long sub- 

 mergence in the waters. Moore said of them: 



. " These lonely columns stand sublime, 



Flinging their shadows from on high, 

 Like dials which the wizard Time 

 Has raised to count his ages by." 



But, on our own shores, beneath the clear waters, and on the hills 

 we cultivate, are records of similar movements, vastly greater in ex- 

 tent, and running Avith marvelous continuity through periods so vast 

 that all the centuries which have passed since the Pozzuoli marbles 

 were erected seem but as yesterday. 



AN AMERICAN ASTRONOMICAL ACHIEVEMENT. 



Br RICHARD A. PROCTOK. 



AN" American astronomer, Prof. Young, of Dartmouth College, 

 Hanover, New Hampshire, has recently achieved a victory over 

 a problem which has for many years foiled the skill of the best Euro- 

 pean observers; and, in so doing, he may be said to have added the 

 keystone to an arch of no small importance in the edifice of modern 

 astronomical science. It will be in the knowledge of most of my 

 readers that astronomers have succeeded, during the last eight years, 

 in measuring the rate at which some of the stars travel from or tow- 

 ard us, employing for the purpose what is called the spectroscopic 

 method. I do not mean here spectroscopic analysis simply, but a 

 special application of this now familiar analysis to measure the rate 

 at which luminous bodies are approaching us or receding from us. 



