SPRINGS. 271 



The temperature of springs, hot, tepid, and cold, is remarkably uniform, under ordinary 

 circumstances, as measured by the thermometer immersed in the water. But it may 

 apparently vary diurnally in tropical countries, like that of rivers and lakes, as estimated 

 by the immersion of the hand a fact which the ancients converted in one instance into a 

 marvel Thus wrote Lucretius : 



" A fount, 'tis rumour'd, near the temple purls 

 Of Jove Ammonian, tepid through the night, 

 And cold at noon-day ; and th' astonish'd sage 

 Stares at the fact, and deems the punctual sun 

 Strikes through the world's vast centre, as the shades 

 Of midnight shroud us, and with gay reverse 

 Madden the well-spring : creed absurd and false. 



Pliny refers to this fountain, with some exaggeration, as cold in the daytime, and scorching 

 hot at night ; and Ovid likewise : 



" Thy stream, horn-crown'd Ammon ! in the midst 

 Chills us at noon, but warms at morn and eve." 



The reported prodigy is a very common-place occurrence, entirely caused by the strongly 

 contrasted temperature of the air in the Libyan desert, which renders the waters still 

 flowing around the ruined temple of Ammon cooler to the senses by day than by night. 



5. Ebullient. Springs displaying violent ebullition, sending off vast clouds of steam, 

 and throwing up their scalding water to a considerable height in the form of a jet, are 

 the common phenomena of volcanic regions. In the island of St. Michael, one of the 

 Azores, there is a round, deep, and lovely valley, its sides covered with myrtles, laurels, 

 and mountain grapes, with wheat, Indian corn, and poplars waving upon its fields, in which 

 many boiling fountains occur. The principal, called the Caldeira, is on a gentle eminence 

 by the side of a river, and boils with great fury, and the river itself exhibits ebullition in 

 various places, where the water is too hot to be borne by the hand. But the most re 

 markable of these springs are found in Iceland, and constitute, owing to their diversified 

 appearances, sublime, beautiful, and terrible objects in that strange region, where the 

 extremes of heat and cold, in the form of ice and fire, are in near proximity. They are 

 found in vai'ious parts of the island, but the chief are situated in its south-western division, 

 on a plain at the base of a low range of hills, about thirty-six miles from Hecla. Here, 

 within a circle of two miles, above a hundred are contained, some of which boil incessantly, 

 without any discharge of their contents, while others cast their waters high into the air. 

 To the principal of these springs the name of Geyser is applied a term derived from the 

 Icelandic geysa, signifying to burst forth with vehemence and impetuosity. There are 

 two, more remarkable than the rest, called the Great Geyser and the New Geyser, whose 

 columns of vapour are seen by the traveller long before he reaches their site. " At the 

 distance of several miles," says Henderson, " on turning round the foot of a high moun 

 tain on our left, we could descry, from the clouds of vapour that were rising and convolv 

 ing in the atmosphere, the spot where one of the most magnificent and unparalleled scenes 

 in nature is displayed." The Geysers are intermittent hot springs ; and on approaching 

 the Great Geyser, when in a quiet state, it presents the appearance of a large circular 

 mound, formed by the depositions of the fountain. Ascending the mound, a spacious 

 basin is seen, partly filled with hot water, clear as crystal, and gently bubbling. In the 

 centre there is a cylindrical pipe or funnel, about eighty feet in depth, and from eight to 

 ten feet in diameter, widening at the top, and opening gradually into the basin. The 

 inside exhibits a whitish surface, consisting of a siliceous incrustation, which has been 

 rendered smooth by the action of the boiling water. The basin is about 1 50 feet round ; 

 and, when full, the water it contains is about four feet deep, measuring from the surface 



