124 



THE FOKMS OF WATER. 



berland, or through the valleys near Beth- 

 gellert in Wales. Under all tlie beauty of the 

 present scenery we should discover the me- 

 morials of a time when the whole region was 

 locked in the embrace of ice. Professor 

 Ramsay is especially distinguished by his 

 writings oil the- ancient glaciers of Wales. 



875. We have made the acquaintance of 

 the Keeks ot Magillicuddy as the great con- 

 densers of Atlantic vapor. At the time now 

 referred to, this moisture did not fall as soft 

 and fructifying rain, but as snow, which 

 formed the nutriment of great glaciers. A 

 chain of lakes now constitutes the chief at- 

 traction of Killarney, the Lower, the Middle, 

 and the Upper Luke. Let us suppose our- 

 selves rowing toward the head of the Upper 

 Lake with the Purple Mountain to our left. 

 Remembering our travels ill the Alps, you 

 would infallibly call my attention to the 

 planing of the rocks, and declare the action 

 to be unmistakably that of glaciers With 

 our attention thus sharpened, we land at the 

 heal of the lake, and walk up the Black 

 Valley to the bas of Magillicuddy 's Keeks. 

 Your conclusion would be, that this valley 

 tells a tale as wonderful as that of Hasli. 



876. We reaeli our boat and row home- 

 ward along the Upper Lake. Its islands 

 now possess a new interest for us. Some of 

 them are bare, others are covered wholly or 

 in part with luxuriant vegetation ; but both 

 the naked and clothed islands are glaciated. 

 The weathering of ages has not altered their 

 forms ; there are the Cannon Rock, the 

 Giant's Coffin, the Man-of-War, all sculp- 

 tured as if tlie chisel had passed over them in 

 our own lifetime. These lakes, now fringed 

 with tender woodland beauty, were all occu- 

 pied by the ancient ice. It has disappeared, 

 and seeds from other regions have been 

 wafted thither to sow the trees, the shrubs, 

 the ferns, and the grasses which now beau- 

 tify Killarney. Mun himself, they say, lias 

 made his appearance in the world since that 

 time of ice ; but of the real period and manner 

 of man's introduction little is professed to be 

 known since, to make them square with sci- 

 ence, new. meanings have been found for the 

 beautiful myths and stories of the Bible. 



377. It is the nature and tendency of the 

 human mind to look backward and lor ward ; 

 to endeavor to restore the past and predict 

 the future. Thus endowed, from data pa- 

 tiently and painfully won, we recover in 

 idea a state of things which existed thou- 

 sands, it may be millions, of years before the 

 history of the human race began. 



56. THE GLACIAL Erocn. 



378. This period of ice-extension lias been 

 named the Glacial Epoch. In accounting 

 for it great minds have fallen into grave er- 

 rors, as we shall presently see. 



379. The substance on which we have 

 thus far been working exists in three differ- 

 ent states : as a solid in ice ; as a liquid in 

 water ; as a gas in vapor. To cause it to 

 pass from one of these states to the next fol- 

 lowing one, heat is necessary. 



330. Dig a hole in the ice of the Mer do 

 Glare in summer, and p ace si thermometer 

 in the hole ; it will suuid ut 32 Fa.hr. Dip 

 your thermometer into one of the glacier 

 streams; it will still mark 32. The water is 

 therefore as cold us ice. 



381. Hence the whole of the. heat j-oured 

 by the sun upon the glacier, and which has 

 I een absorbed by the glacier, is expended ia 

 simply liquefying the ice, and not in render- 

 ing either ice or water a single degree warmer. 



382. Expose water to a lire ; it becomes 

 hotter for a time. It boils, and from that 

 moment it ceases to g t h< tter. After it has 

 begun to boil, all the hrni communicated by 

 the fire is carried away by the steam, t?iouyh 

 the steam itself is not the least fraction -fa de- 

 gree hotter than the wafer. 



883. In fact, simply to liquefy ice a large 

 quantity of heat is necessary, and to vaporize 

 water a still larger quantity is necessary. 

 And inasmuch as thi> heat does not render 

 the water warmer than the ice, nor the steam 

 warmer than the water, it was at, one time 

 supposed to be hidden in the water and in the 

 Fleam. And it was therefore called late/it 

 heat. 



884. Let us ask how much heat must the 

 sun expend in order to convert a pound 

 weight of the tropical ocean into \upor? 

 This problem has been ticcurately solved by 

 experiment. It would require in round num- 

 bers 1000 times the amount of heat necessary 

 to raise one pound of water one degree in 

 temperature. 



383. But the quantity of heat which wou'.d 

 raise the tempi rature of a pound of water 

 one degree would raise the tempt rature of a 

 pound of iron ten degrees. This has been 

 also proved by experiment. IK-nee to con- 

 vert one pound of the tropical ocean into 

 vapor i he sun must expend 10,000 times as 

 much heat as would laise one pound of iron 

 one degree in temperature. 



386. This quantity of heat wr.uld raise the 

 temperature of 5 Ibs. of iron 20UO degrees, 

 which is the fusing point of cast iron ; at 

 this temperature die metal would not only be 

 white hot, but would be passing into the mol- 

 ten condition. 



387. Consider the conclusions at which we 

 have now arrived. For every pound of 

 tropical vapor, or for every pound of Alpine 

 ice produced by the congelation of that va- 

 por, an amount of heat has been expended 

 by the sun sufficient to raise 5 Ibs. of cast- 

 iron to its melting-point. 



388. It would not be difficult to calculate 

 approximately the weight of the Mer do 

 Glace and its tributaries to say, fbr exam- 

 ple, that they contained so many millions of 

 millions of tons of ice and snow. Let the 

 place of the ice be taken by a mass of white- 

 hot iron of quintuple the weight ; with such 

 a picture before your mind you get some 

 notion of the enormous amount of heat paid 

 out by the sun to produce the present glacier. 



389. You must think over this, until it is 

 as clear as sunshine. For you must never 

 henceforth fall into the error already referred 



