56 PENIKESE. 



temperature that changes occur. If ever our island 

 (Penikese) was below the sea, why not find the same 

 rolled pebbles and low-tide marine animals? No sea 

 has been beating here, for we find no sand or loam 

 has been washed away. All the loose materials re- 

 main in place. The greater part of the local pecu- 

 liarities, such as depressions and inequalities, will 

 have been produced by rain. Glacial action will ex- 

 plain the peculiarities we see on land here. There 

 is nothing so hard to protect as a man's intellect. 

 We can get no patents on our investigations." 



The same subject follows in his next, or fifth lec- 

 ture: 



"A geological period or age ago, the surface of the 

 earth was covered with boulders; this was before 

 there were either plants or animals to be found upon 

 it. Now to understand and to translate the trans- 

 portation of glacial rocks we must understand the 

 formation of glaciers. The idea of glacial motion 

 originated with the peasants of Switzerland. A civil 

 engineer, Werner by name, and a peasant, Charpentier, 

 however, got much of the credit for field observation 

 which I had myself done. In 1837 no geologist ad- 

 mitted that rocks were^moved by glaciers; most of 

 them admit it now, though in a somewhat modified 

 condition. The early scientists who were interested 

 in and studied into this subject, were Scheuchzer, 

 who also first described several fossil fishes; Horace 

 Benedict de Saussure, who published his travels in 

 the Alps, and who first described glaciers; Charp- 

 entier, who studied them considerably and published 

 articles upon them; and myself, Professor Forbes, 

 and Mr. Tyndall, who, lately, described their physi- 

 cal constitution, action, etc. Of these Mr. Tyndall's 

 work is the best. We now come to the question, 

 What is a glacier? 



"Glaciers are composed of different materials ac- 

 cording to the positions selected for investigation. 

 On mountain tops they are mere snow fields; deeper, 



