Narrative of the surveying voyages of his majesty's ships Adventure and Beagle (vol.3)

626 ADDENDA. say, " The ice lay much closer here ; and numerous masses adhered to the bottom, under the water, which obliged us to search a passage out from the shore." Further on (p. 220) they say, " But nowhere had the thaw penetrated more than two inches beneath the surface (of the land), while under wat' • along the shore, the bottom was still impenetrably frozen." This was on the second of August. It should, however, be observed, that the sea along this part of the American coast is extremely shallow. Page 321. I have given my reasons for believing that the temperature of the mineral springs of Cauquenes, was permanently changed by the earth- quake of 1822. This inference is altogether false, for I find that Schmidtmeyer, in his Travels in Chile during the years 1820 and 1821, says (p. 31 1) that the temperature of the different springs was 83°, 103°, 106°,. 112°, 117° and 118° of Fahrenheit. Now Mr. Caldcleugh says, after the earthquake of February, 1835, the temperature fell from 118° to 92°. Previously, therefore, to this shock, it had regained the tempera- ture which it had in 1820, Page 377. When I offered my views on the cause of the great waves, which follow earthquakes on certain coasts, I was not aware of the paper on this subject by Sir James Hall in the Edinburgh Royal Transactions, vol. vii., p. 154. I cannot, however, perceive the necessity of a sudden elevation of the bot- tom, to produce the observed effects, as supposed by that distinguished philosopher. Having read the abstract of a Notice on the Resistajice of Water, by Mr. Russell, I perceive the subject is far more intricate, than I was at the time aware. Page 381. I have said that during the few months subsequently to the great shock of February, 1835, at Concepcion, upwards of three hundred tremours were felt, but I should have said, within twelve days. (See Geograph. Journal, vol. vi., p. 322. Sketch of Surveying Voyage of the Adventure and Beagle, by Captain FitzRoy), From some additional informal -"hich I have met with since finishing this chapter, I find the train ot volcanic plieno- mena, which followed this earthquake, affected a larger area than that mentioned (seven hundred by four hundred miles), and affected it in a manner which gives great additional weight to the argument that South America is in that part a mere crust resting over a sheet of fluid rock ;