288 DAVENPORT ACADEMY OF NATURAL SCIENCES. 



proceeded to show that a ball, while suspended from a bracket attached 

 to the wheel and turning with it, when started to swinging in a certain 

 direction, had a tendency to continue its swing in the same direction 

 as at first, and that, the table being revolved horizontally, the direction 

 of the swing of the ball would not change with it. Thus an ant, for 

 example, being upon the table and observing the swing of the ball and 

 not being aware of the movement of the surface on which he stands, 

 would see the direction uf swing constantly changing in relation to a 

 graduated circle on the surface beneath the ball. It was explained 

 that we are in similar circumstances op the surface of the planet whose 

 motion is imperceptible to us as we move with it. Hence, as the ball 

 swings on a circle drawn upon the floor, the floor itself, turning with 

 the building and the earth's surface, changes its position under the 

 swinging ball whose direction does not change, just as the turntable 

 changes under the small ball as above described. It was shown that 

 at the pole such change would be around the entire circle in 24 hours 

 while at the equator there would be no change. 



After some furthar explanation of details and discussion of the sub- 

 ject the meeting adjourned at 9:30 to the museum and basement to 

 see how the ball was acting. Truly enough, it was found to have 

 apparently changed from the north and south direction and was 

 swinging about ten degrees east of north and west of south. Then 

 it was realized that not the swing of the ball but the position of the 

 building itself had thus changed, and that in i^ hours a visible mo- 

 tion of rotation of the earth had taken place, producing the relative 

 displacement due to this latitude. 



March 28, i8go. — Regular Meeting. 



President McCowen in the chair; nine members present. 



A vote of thanks was extended to Mr. L. M. Crawford of Vinton, 

 Iowa, for valuable specimens donoted, and for his offer of gratuitous 

 services as taxidermist. 



President McCowen and Curator Pratt were instructed to call on 

 Mrs. C. C. Parry and express the desire of the Academy to retain in 

 its museum the valuable herbarium collected and deposited by Dr. 

 Parry. 



The Curator then took up the vexed subject of the "Antiquity of 

 the Mound Builders," citing evidence and authority for the claim that 

 they antedate all known Indian races or tribes. 



