98 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



extending probably over the greater part of the ocean. South 

 of the Vineyard Islands, and to the eastern end of Long Isl- 

 and, the silicious sand is replaced by a kind of bluish mud 

 known as the Block Island soundings. A similar mud is 

 found off Sandy Hook in a range of depressions known as 

 mud-holes, which form a leading mark by which to find the 

 port of New York in thick weather. A few rocky patches 

 are found east of the neighborhood of New York, and a rocky 

 bottom occurs, sparingly, near Cape Fear, but otherwise the 

 sand is pretty uniform, varying only in the size of its grain. 

 On the inner edge of the Gulf Stream there is a deposit of 

 green sand composed of the cast-off foraminifera. 



DIMINUTION IN THE SIZE OF SWISS GLACIERS. 



Owing to various climatological causes, a remarkable de- 

 crease in the lower borders of the Swiss glaciers took place 

 during the year 1870, and careful trigonometrical measure- 

 ments of their summits revealed a corresponding depression. 

 One ice-peak in the Tyrolese Alps, which formerly was a lit- 

 tle over eleven thousand Vienna feet in height, has been re- 

 duced, within a few years past, to the extent of eighteen and 

 a half English feet, leaving only three instead of four points 

 in these Alps reaching the former altitude. 7 (7, G 71, v., 304. 



LAND-SLIDES. 



During the present year there has been an unusual number 

 of land-slides and sinkings of the ground over considerable 

 areas in different parts of the country, one of the most strik- 

 ing being the dropping out, so to speak, of a portion of the 

 harbor of St. John, New Brunswick, last winter. Quite late- 

 ly, again, three acres of land on the IJelaware division of the 

 Erie Railway suddenly sank below the ground to the depth 

 of about forty feet, leaving the tops of the trees just visible 

 above the surface. As an instance of a more gradual sinking 

 of an extended region, it is said that the islands of Jersey and 

 Guernsey, in the British Channel, have subsided to the extent 

 of forty feet in five hundred years. 



CONNECTION OF EARTHQUAKES W r ITH MAGNETIC CURRENTS. 



Mr. Varley has lately expressed the belief that many earth- 

 quakes are due to the action of magnetic currents through 



