40 TRANSACTIONS OF THE [.TAN. 12, 



itself, the motion imparted to the ends of the T 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 T has become horizontal, some obstacle 

 prevent its moving still further 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 instrmnent. 



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 ex- 

 tremities of the T getting a motion, one to the j-ight and the 

 other to the left, when the T is vertical. Now if the T 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 phenomena of the 

 Gyroscope. 



The paper was illustrated by apparatus, and discussed by 

 Prof. W. LeConte Stevens and Mr. Francis Collingwood. 



January 12th, 1885. 

 Adjourned Business Meeting. 

 Yice-President Prof. D. S. Martin in the chair. 

 Twenty-eight persons present. 



The report of the Council, which recommended the appro- 

 priation of one hundred dollars for the Popular Lecture Course, 

 and the election of nominees was adopted. 



The following persons were elected Resident Members : 

 Mr. E. H. Talbott, Mrs. J. A. Gallaher, Mr. C. E. 



MUNSELL. 



Prof. O. P. Hubbard exhibited some " crows-feet,'' or Cal- 

 trops, found in cutting through an old fort in western Penn- 

 sylvania. The four points are barbed, in which they are unlike 

 the figures in Webster's Dictionary and Rawlinson's Ancient 



