A PRIMITIVE GYROSCOPE IN LIBERIA 



531 



most of the then existing animal and 

 plant forms, pushed south before its ad- 

 vance, had not time enough to adapt 

 themselves to their new environment, 

 and therefore became greatly altered or 

 exterminated. 



As yet there has been no good reason 

 assigned for a change that in a compara- 

 tively short time transformed the semi- 

 tropical climate into that of Greenland 

 of today. Probably a combination of 

 circumstances brought it about. 



Be that as it may. the fact remains 

 that over certain centers — one on the 

 east of Hudson Bay, the Labradorian; 

 another on the west of it, the Keewatin ; 

 and a third in the Canadian Rockies, the 

 Cordilleran — snow, gradually changing 

 into ice, accumulated year after year to 

 such immense thicknesses that finally, 

 impelled by its own weight, motion be- 

 gan, and three giant glaciers crept out 

 over the adjacent coinitry. These finally 

 joined into a continental ice mass that at 

 its greatest extent covered two-thirds of 

 North America — an area of about 4.000,- 

 (X)0 square miles. 



While there may have been some dif- 

 ference in time at which the various ice 

 centers reached their greatest develop- 

 ment, we will be very near the truth in 

 saying that from the southern limit. 



shown on the map, northward the ice 

 lay in one unbroken expanse, with the 

 exception of the so-called Driftlcss Area 

 and possibly one of the highest mountain 

 peaks in the East. It is calculated that 

 its thickness at the two eastern centers 

 must have been something like 5,000 to 

 10,000 feet. 



On its way from the north the ice 

 mass gathered to itself immense quanti- 

 ties of soil and loose rock, which were 

 carried along with it. Occasionally huge 

 blocks of rock from mountain slopes and 

 stream bottoms were clutched in the firm 

 grip of the ice and carted for hundreds 

 of miles. Frequently the ice would lift 

 great boulders from the bottom of a val- 

 ley to the top of a mountain. 



Presently the ice began to retreat be- 

 fore a more congenial climate. It was 

 not at first, however, a steady retreat, as 

 not less than four times the ice again 

 advanced after having almost vanished, 

 and each time it was followed by animals 

 and plants adapted to the semi-frigid 

 climate at its edge. During one of these 

 interglacial epochs man appeared upon 

 the scene. 



But as the ice melted and disappeared 

 the earth and rocks which it carried were 

 dumped, sometimes as an even mantle, 

 but more often in hills and ridges. 



A PRIMITIVE GYROSCOPE IN LIBERIA 



By G. N. Collins 



THE recent applications of the 

 gyroscope in the Brennan mono- 

 rail and as a means of steadying 

 steamships, as well as the present popu- 

 larity of toys based on this principle, re- 

 call a gyroscopic toy in use among the 

 Golahs of Liberia, West Africa. Certain 

 members of this primitive tribe have 

 developed a very remarkable skill in 

 manipulating this top-like toy,' which they 

 keep spinning for any length of time in 

 midair merely by wdiipping it. 



Interest in this primitive gyroscope 

 has been further increased bv the botan- 



ical identification of the fruit from which 

 the tops are made. Air W. T. Swingle, 

 of the Department of Agriculture, ])oints 

 out that these hard-shelled, spherical 

 fruits belong to the genus Balsamocitrus, 

 a very near relative of the ball fruits of 

 India and a more distant relative of the 

 orange. 



These fruits may well be described as 

 hard-shelled oranges (see page 532). 

 They are from three to five inches in 

 diameter. The shell is very hard and 

 from one-quarter to one-half inch in 

 thickness. 



