SHIFTING OF THE EARTH'S AXIS 433 



County to have this two-mile strip taken from the latter and added to 

 the former. After dragging through the courts for a number of years 

 the matter was finally decided in favor of Trinity County, the argument 

 being that, inasmuch as it is impossible, by ordinary processes of sur- 

 veying, to locate the parallel with absolute accuracy, the original survey, 

 made by due process of law and accepted by both counties, although 

 admittedly largely in error, should remain the official boundary line. 

 The amount of territory, mountainous and sparsely settled, is a com- 

 paratively small part of either county, Mendocino County being nearly 

 as large as the state of Connecticut. The question was, however, of 

 considerable importance to the property owners of the two-mile strip. 

 After the land was claimed by Mendocino County, it was assessed and 

 taxed by both counties, and the taxpayers who cast their lot with 

 Mendocino County now have several years of back taxes to pay in 

 Trinity County. 



Doubtless most of the readers of this article have already wondered 

 what may be the cause of the shifting of the earth's axis. In 1765, 

 Euler, a famous Swiss mathematician, demonstrated, as a proposition 

 in dynamics, that if a free rigid oblate spheroid rotates about an axis 

 which differs slightly from the axis of figure, or shortest axis, then the 

 axis of figure will revolve about the axis of rotation in a period the 

 length of which will depend upon several factors. He computed that, 

 if the assumed conditions obtained for the earth, then the period of 

 revolution of the axis of figure about the axis of rotation would be 306 

 days. Obviously, however, the earth is not rigid; the oceans are quite 

 plastic and the ground itself is possessed of some elasticity. Professor 

 rTewcomb computed some years ago that, if we assume the earth as a 

 whole to possess the rigidity of steel, then the period of revolution of 

 the one axis about the other would be 441 days, as against 306 days 

 found by Euler on the assumption that the earth is perfectly rigid. 

 The actual observed period is fourteen months, or 427 days, and the 

 legitimate conclusion to be drawn is that the earth as a whole is some- 

 what more rigid than steel — a conclusion that agrees with that derived 

 by Lord Kelvin and others from entirely different considerations. 



JSTow the question arises, Why does the earth not rotate upon its 

 shortest axis? The explanation is simple. If the earth ever did 

 rotate upon its shortest axis it could not continue to do so because of 

 the shifting of matter upon and within the surface. Winds, rains, 

 rivers and ocean currents are ceaselessly transporting matter from point 

 to point, and during the winter great masses of snow and ice accumulate 

 in the temperate and frigid zones only to disappear again in the 

 summer. Although these effects will, to a large extent, neutralize each 

 other, the sum total can not be other than to produce at least a theoret- 

 ical lop-sidedness to the earth; and as soon as this takes place there 

 must be a shifting of the axis of rotation. The time of revolution of 



vol. i,xxv. — 29. 



