74 AN INTERESTING GEOLOGICAL LOCALITY. 



slow horizontal movement, and a slow motion of the disk 

 makes a quick horizontal movement. 



A careful consideration of the above will render it 

 easy to see why the Gyroscope ceases to maintain itself 

 if the lateral (or horizontal) motion is stopped, for, in 

 order to maintain itself, the motion imparted to the 

 ends of the tee-square, when vertical, must be expended 

 in lifting. If spent in any other way, nothing is left to 

 overcome gravity. Now if, as the square falls, and the 

 tee has become horizontal, some obstacle should prevent 

 its moving still farther to the right, its motion in this 

 direction would cease, and, of course, when it arrived 

 at the lowest point nothing would be left to lift the 

 instrument. 



Another paradox is that the instrument must fall 

 some in order to produce any of its peculiar phenomena ; 

 but this, too, is easily explained. Everything depends 

 upon the two extremities of the tee getting a motion, 

 one to the right and the other to the left, when the tee 

 is vertical. Now, if the tee does not fall, or if it is not 

 lifted up, — for either movement will do equally well — 

 there will be no such motion : only, if the first sends the 

 instrument north the other will send it south. 



This, directly or impliedly, explains all the phe- 

 nomena of the Gyroscope. 



NOVEMBER 21, 1883— FIFTEENTH STATED MEETING. 



Prof. W. B. I) wight, chairman, presiding ; eight mem- 

 bers and twenty five guests present. 



Dr. Stevenson reported five hundred fifty-five speci- 

 mens that had been received for the museum. 



Mr. John I. Piatt was elected a member. 



The following paper was read : 



AN INTERESTING GEOLOGICAL LOCALITY AT CORN- 

 WALL, ORANGE COUNTY, N. Y. 

 BY PROF. W. B. DWIGHT. 



My visit to this locality occurred on September 22, 

 1883, and occupied but a few hours of that day. It was 



26 



