c 



& 



c 



0-4 



445 



0-7 



0-5 



465 



0-8 



0-6 



487 



0-9 



%' 



c 



&' 



609 



1-3 



723 



645 



1-4 



764 



684 



1*5 



8.06 



A. Winchell — Trend and Crustal Surplusage. 417 



The computed values of Q and §/ for different values of c 

 are 



& c 



513 1-0 



543 1-1 



575 1-2 



18. The absolute velocity of the meteoroids that come into 

 the earth's atmosphere must be in general greater than the 

 earth's velocity. For otherwise the number of shooting stars 

 seen in morning hours would be much greater relatively to 

 those seen in evening hours than observations show. Comets 

 and meteors have like orbits, and no known comet would have 

 at a distance unity a velocity as small as the earth's velocity. 

 Therefore the term k log P that enters into the expression for 

 p x applies to only a small part of the meteoroids. Remember- 

 ing this, and also the considerations stated in section 15, we 

 may safely say that in the solar system p^>100p, that is, that 

 the effect upon the earth's motion of the meteors that come into the 

 earth's atmosphere exceeds at least one hundred fold that of the 

 meteors that pass by without .impact. 



Art. LII. — Sources of Trend and Grustal Surplusage in Moun- 

 tain Structures ;* by Alexander Winchell. 



Two facts in mountain structure have baffled, hitherto, the 

 attempts made to arrive at a comprehension of the mechanics 

 of mountain formation. The north-and-south trend of the 

 profounder physiographic features of the earth has no light 

 thrown upon it by any of the orogenic theories commonly en- 

 tertained. It appears also, from calculations made by Captain 

 C. E. Dutton, Rev. O. Fisher and others, that the shortening of 

 the earth's circumference in cooling from the incrustive stage to 

 the existing temperature would be insufficient to supply the 

 folds and plications wrought into the structure of the mountains. 

 Professor E. W.' Claypole has reached a similar result from 

 approximate measurements across a portion of the Appala- 

 chian chain in Pennsylvania. These determinations, so far as 

 they are valid, reveal an insufficiency in the contractional the- 

 ory. Still the mechanical principles of the theory cannot be 

 successfully assailed; and it becomes necessary to seek for 

 some cooperative cause which has hitherto been overlooked. I 

 venture to contribute one suggestion toward the explanation of 

 meridionality, and another suited to aid in the explanation of 



* Substance of a communication presented to the Geological Section of the 

 American Association, August 21, 1885. 



