This difference between my calculations and those of Dr. Geinitz, Hochstetter, and others, chiefly rests on the origin we have assigned for the sea waves. Dr. Geinitz, for instance, although he says that the origin of the 1877 earthquake was not on the continent but to the west in the ocean, bases all his calculations on the assumption that the _centrum_ was at or near to Iquique, and the time at which that city was disturbed was the time at which the waves commenced to spread across the ocean. This time is 8.25 P.M. At this time, however, it appears that the waves must have been more than double the distance between the true origin and Iquique, from Iquique on their way towards the opposite side of the Pacific. Introducing this element into the various calculations which have been made respecting the depth of the Pacific Ocean as derived from observations on earthquake waves—which element, insomuch as the waves appear to have come in to inundate the land some time after the shock, needs to be introduced—we reduce the velocity of transit of the earthquake wave and, consequently, the resultant depths of the ocean. Key: A Distance from the origin in miles (calculated in great circles) B Velocity in feet per second +-----------+---------+---------+-----+-----+---+-------+--------+---------+ | | | Arrival |Time | | |Depth | |Interval | | | | of wave |taken| | |of the | Height | between | | |Longitude| in | by | A | B |ocean | of |waves in | | | |Greenwich|wave | | |in feet| waves | minutes | | | |mean time| | | | | | | +-----------+---------+---------+-----+-----+---+-------+--------+---------+ | | ° ′ |day h. m.|h. m.| | | | | | |Origin | | | | | | | | | | of wave | 71 5 W.| 9 12 59| | | | | | | |San | | | | | | | | | Francisco|122 32 |10 2 28|13 29|4,578|498| 7,721 | 9 in. | | |Callao | 77 15 | 9 17 9| 4 10| 658|231| 1,657 | | | |Iquique | 70 14½ | 9 13 21| 0 22| 87|348| 3,770 | 20 ft. |22 | |Cobija | 70 21 | 9 13 19| 0 20| 80|352| 3,857 | 30 „ | | |Mejillones | 70 35 | 9 13 27| 0 28| 108|339| 3,587 | 35 „ |15 or 45 | |Chanaral | 71 34 | 9 15 26| 2 27| 455|272| 2,309 | |10 | |Coquimbo | 71 24 | 9 15 15| 2 16| 508|328| 3,363 | |30 | |Valparaiso | 71 38 | 9 16 16| 3 17| 695|310| 3,000 | | | |Concepcion | 73 5 | 9 16 52| 3 53| 928|350| 3,824 | |12 to 15 | |Honolulu |157 55 |10 3 52|14 53|5,694|561| 9,807 |34 to |25 | | | | | | | | | 54 ft.| |