at the distance of a degree of a great 

 circle from Lisbon, and a degree and 

 a half from Oporto. 



With singular prescience he believed 

 that probably earthquakes are not of 

 comparatively deep-seated origin a con- 

 clusion which is now generally held by 

 seismologists. He was well aware that 

 data were then wanting on which to base 

 any satisfactory estimate as to the depth 

 of the focus, which might vary con- 

 siderably, but he thought that " some 

 kind of guess might be formed concerning 

 it." Hazarding what he called "a ran- 

 dom guess," he believed that the depth 

 at which the impulse of the Lisbon 

 earthquake started, " could not be much 

 less than a mile or a mile and a half, and 

 probably did not exceed three miles." 



In considering the merit of Michell's 

 Earthquake paper as a contribution to 

 science we must remember that he him- 

 self modestly offered it as pretending to 

 be no more than " conjectures." That so 

 34 



