i8 9 6. THE CONSTANTINOPLE EARTHQUAKE. 31 



first sight, one feels disposed to accept such a statement without 

 question. The Observatory clock is not, however, regulated by 

 transit, but by sextant, observations, and the latter are not nearly as 

 exact as the former. Moreover, there is a considerable difference 

 between Mr. Coumbary's estimate and those which Mr. W. H. Wrench, 

 the British Consul-General at Constantinople, kindly obtained for 

 me (5). He ascertained that the regulating clocks of two prominent 

 watchmakers in the city were stopped, one at 0.20^ and the other at 

 0.2 if, the owner of each clock being confident that his time was 

 correct. But Mr. Wrench informs me that there is no standard 

 clock in Constantinople capable of giving correct time, so that the 



Fig. 2. — Constantinople Earthquake-Pulsations as recorded by the 

 Vicentini Micro-seismograph at Siena. 



close agreement between these two estimates may be only accidental. 

 On the whole, therefore, while recognising that a doubt exists on the 

 point, I think that Mr. Coumbary's time is likely to be nearer the 

 truth than the others. If it may be regarded as correct, then the 

 larger pulsations must have travelled outwards with an average velocity 

 of two miles a second ; but if one of the other times be adopted, as 

 Dr. Cancani thinks desirable (4), then the average velocity would be 

 either 1-4 or i-6 miles per second. The correct value thus probably 

 lies between 1^ and 2 miles per second. 



Depth of the Seismic Focus. — To ascertain the depth of the 

 seismic focus, Mr. Eginitis has employed the well-known method used 



