262 HOBBS— THE EVOLUTION AND THE [April 24. 



by elimination of the false and augmentation of the true, whereas a 

 theory essentially false yields nothing, and by discouraging effort 

 bars the way to progress. With the aid of mathematics and by an 

 abundance of exact observation, the more or less occult Aristotelian 

 theory was by Mallet clothed in a modern dress and thus made 

 respectable in the company of the modernized sister sciences. The 

 cause of the earthquake disturbance was by the very nature of the 

 theory hidden so deep beneath the earth's surface as to be removed 

 from direct observation, and was, therefore, a matter suitable only 

 for speculation. 



At the opening of the twentieth century, almost fifty years after 

 Mallet had modernized the theory of Aristotle, authors of text- 

 books of geology quite generally disposed of the subject of earth- 

 quakes by a treatment of the outlines of the Mallet theory in the 

 compass of a few pages. How generally the investigation of earth- 

 quakes was excluded from the field of research in geology is strik- 

 ingly shown by the activities of the United States Geological Survey, 

 a bureau employing the largest staff of working geologists of any in 

 the world and including in its field subjects as diverse as paleon- 

 tology and mineral resources. In the years 1868, 1872, 1886 and 

 1887 earthquakes of the first magnitude wrought damage to property 

 within the national domain, and with one exception no effort was 

 made by the national bureau to investigate these phenomena, and but 

 little by independent geologists. Since the intellectual shock from 

 the California earthquake of 1906, individual geologists have begun 

 to take advantage of this opportunity for study, even though the 

 golden opportunity had already passed. 



The Process of Averaging in Mapping Isoseismals and Coseis- 

 mals. — Aside from its occult and speculative basis, which removes 

 it from the reach of direct observational studies, the centrum theory 

 has yet assumed to adopt the observational method of modern sci- 

 ence. The isoseismal and coseismal lines which belong to the Mallet 

 conception of an earthquake centrum must be obtained through 

 averaging the results of observation either of the intensity of the 

 shocks or of the time of their arrival. In how far it has been nec- 

 essary to "adjust" data in order to make the circular or elliptical 

 curves concentric about the epicenter and represent uniformly de- 



