70 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



attributing the phenomenon to variations in the atmospheric 

 pressure; and it is believed that it will be found to occur in 

 all laroje bodies of water. 



His investigations have led him to the conclusion that the 

 seiche is an oscillatory undulation, having a true rhythm, and 

 that the phenomenon is not occasional, but constant, though 

 varying in degree. The duration of a seiche is a function of 

 the length and depth of the section of the lake along which 

 it oscillates ; this duration increases directly with the length 

 and inversely with the depth of the lake. The instrument 

 he has devised for the investigation of the phenomenon is a 

 " tide measurer." 12 A, Jane 17, 1875, 134. 



SECULAR CHANGES IN THE LEVEL OF THE OCEAN. 



Professor Schmick has called attention to the fact that his 

 theory of the existence of regular periodical changes of the 

 level of the sea, and especially of a secular movement from 

 the northern to the southern hemisphere, is apparently sup- 

 ported by the conclusion of the astronomer Nyren. The lat- 

 ter has shown that the latitudes of all well-determined ob- 

 servatories in the northern hemisphere have slightly dimin- 

 ished since accurate observations began. This phenomenon 

 is, according to Schmick, easily explained by the hypothesis 

 that the water of the Southern Ocean is now about perhaps 

 two feet deeper than it was a hundred years ago, which hy- 

 pothesis accords precisely with the conclusion to which he 

 was led by the entirely different course of reasoning pub- 

 lished by him some years ago in his works on floods, etc. 

 Gaea, XL, 29. 



TIDES OF THE EASTERN ALEUTIANS AND THE NORTH TACIFIC 



In the appendix to the United States Coast Survey Report 

 for 1872, now in press, is a report by Mr. W. IT. Dall on the 

 tides, currents, and meteorology of the Eastern Aleutian re- 

 gion and the Northeast Pacific, accompanied by explanatory 

 diagrams. Mr. Dall's observations on the oceanic currents, 

 which are here tabulated and discussed up to the date of the 

 report, are of special interest, as being the first series under- 

 taken with a direct view to the solution of the 'problems in 

 question, and result in the proof of there being a reflexed 

 northerly arm of the great easterly North Pacific current, de- 



