Narrative of the surveying voyages of his majesty's ships Adventure and Beagle (vol.2): between the years 1826 and 1836 : describing their examination of the southern shores of South America, and the Beagles's circumnavigation of the globe

413 BAROMETER — CHANGES OF LEVEL. Feb. sudden a fall, not followed by bad Aveather, may have been connected with the cause of the earthquake ; but some doubt hangs over these observations. The barometers on board the Beagle, at that time in Valdivia, did not indicate any change. StiU, at so great a distance, it does not follow that the mercury should move similarly ; and (notwithstanding doubts excited by persons at Concepcion who had frequently looked at Cap- tain Delano''s barometer,) I am hardly inclined to disbelieve the extract from his register which he gave me. In a river near Lirquen, a woman was washing clothes at the time of the great shock. The water rose instantaneously, from her feet half wa}' up her legs ; and then subsided gradually to its usual level. It became very muddy at the same time. On the sea-beach the water swelled up to high-water mark, at the time of the shock, without having previously retired. It then began to retire, and contirmed falling about half an hour, before a great wave was seen approaching. For some days after the devastation the sea did not rise to its usual marks, by four or five feet vertically. Some thought the land had been elevated, but the common and prevailing idea was, that the sea had retired. This alteration gradually diminished, till, in the middle of April, there was a difference of only two feet between the existing, and former high-water marks. The proof that the land had been raised exists in the fact, that the island of Santa Maria was upheaved some feet more than other places. In going through the narrow passage which separates Quiriquina from Tumbes, the great waves had swept the steep shores to a height of thirty feet (vertically) above high-water mark ; but this elevation was attained, in all probability, only at the sides of the passage, where the water met with more obstruction, and therefore washed up higher. That passage is nearly one mile in width, and has ten fathoms water in the middle ; but the rocks on the western side diminish its navi- gable width to half a mile. Wherever the invading waves found low land, the destruction was great, from those lands being in general well cultivated, and