B. TERRESTRIAL PHYSICS AND METEOROLOGY. 123 



THE FORCE OF SEA WAVES. 



In connection with a memoir on the Manora Breakwater, 

 read before the Institution of Civil Engineers, London, by 

 W. H. Price, some remarks were made by Mr. David Steven- 

 son and others on the effect of sea waves in breaking up 

 heavy masses of masonry. A remarkable instance of the 

 power of such waves was afforded in the case of the break- 

 water at Wick, on the coast of England. The height of the 

 waves at this place was several times measured and esti- 

 mated, the result being about forty-two feet from crest to 

 hollow. Stones of eight and ten tons' weight were by such 

 waves carried from the parapet to the top of the break- 

 water. It was resolved finally to construct the outward ex- 

 tremity of the breakwater by depositing three courses of 

 one-hundred-ton blocks of stone on the rubble base, as a 

 foundation for three courses of large flat stones, surmounted 

 by a monolith of cemented rubble built on the spot. The 

 end of the breakwater, therefore, was in substance a monolith 

 weighing upward of eight hundred tons, being about 26 

 feet by 45, and 11 feet in thickness, cemented to the under- 

 lying rubble base. Incredible as it might seem, this huge 

 monolithic mass succumbed to the force of the waves. It 

 was actually seen by the resident engineer to be bodily slewed 

 around by successive strokes, until it was finally removed 

 and deposited inside of the pier. In fact, not only the upper 

 portion, but the three lower courses of stone, forming a mass 

 of 1350 tons, were removed without breaking. 3Ii7iuies and 

 Proceedings Institutio7i of Civil Engineers^ London^ 1876, 40. 



CLIMATE OF THE CAUCASUS. 



Dr. Radde, in some remarks on the geology of the Cauca- 

 sus, sliows that the physics of the surrounding land is ren- 

 dered entirely different by the presence of these great 

 mountain ranges. The limit of perpetual snow in the Cau- 

 casus sinks to ten thousand feet in the moist districts of 

 Colchis,but rises on the northern side of the Caucasus, where 

 the dry east and northeast winds prevail, and where there 

 can be only a slight precipitation of snow, until on Mount 

 Ararat, even at the height of 14,300 feet, vegetation is found. 

 There is, therefore, a difference of at least 4000 feet in the 



