86 Generating Economic Cycles 



range in the barometer, due to the change of the eun 

 in latitude from +23° to -23°, causing the change 

 in the seasons, the difference between winter and 

 summer, is shown by Table 54 to be about 0.100 

 inch, we conclude that we are dealing with a phenome- 

 non which at times is seven-tenths of the annual depar- 

 ture in its intensity. The fact is that the barometric 

 pressure is sometimes maintained higher than the 

 average throughout the entire year over a large 

 continental area in middle latitudes, and that it 

 often equals at least half as much as the influences 

 of the sun's action on the atmosphere by departing 

 23 degrees in latitude from the equator; in other 

 years the pressure is kept lower than the average by a 

 similar amount. The years of maximum pressure are 

 1874-75, 1882-3, 1890, 1896-7, with an interval of 

 about 8 years between them successively; the years of 

 minimum pressure are 1878, 1884-5, 189S, also having 

 an interval of about 8 years. ..." 



" In seeking for the causes of this phenomenon, I 

 confess that it has been difficult to assign one which 

 is satisfactory. It cannot be a wave motion because 

 the duration of each wave is too long to admit 

 of anything resembling propagation. One suspects 

 that there may be a tilting of the atmosphere from 

 one continent to another, or from one hemisphere 

 to the other, but when we consider the rapid mo- 

 tion of the upper strata of the atmosphere, it does 

 not appear how it can so far deviate from its usual 

 paths as to leave an entire continent lower or 

 higher than the average for so long a time. One 

 may also suspect purely cosmical causes due to the 



