124 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 3 5 



mentary schools need not be uprooted; for the revival of prosperity 

 produced marriage, especially among those in a humble position who 

 could not write, as well as a decrease in unemployment; so that the 

 last two factors varied similarly. We see, then, that we may be mis- 

 led if we do not take into account all the factors that may be opera- 

 tive. In other words, statistical methods like logarithm tables are 

 invaluable as a tool for giving correct numerical results with the 

 minimum of mental labor ; but neither tool possesses imagination or 

 judgment, and neither of them is a substitute for expert knowledge 

 of the subject to which it is applied. 



FiGUBB 4. — Illiteracy and unemployment. 



Let us now turn to the North Pacific Ocean, which, in spite of its 

 limited access to the Arctic seas, is subject to fluctuations very simi- 

 lar to those of the North Atlantic. A similar treatment yields figure 5, 

 in which increased pressure gradients go with high temperature to 

 the northeast and southwest, and low temperature to the north- 

 west and southeast. It will be noted that in both the North Atlantic 

 and Pacific Oceans a fluctuation is classed as positive when the pres- 

 sure gradient is strong and the wind circulation is active. 



The largest known system of related seasonal weather is that 

 called the " southern oscillation " (or " southern fluctuation "), which 

 has features in the southern summer of December to February some- 

 what different from those of the southern winter of June to August. 

 It will be seen in figures 6 and 7 that at both times of the year the 



