Haupt.] 



158 



[Jan. 18, 



Great Lakes which, in the passage quoted, are undoubtedly the waters 

 alluded to by the Board, there are continual oscillations of even greater 

 magnitude than are found to be produced by the tides in the Gulf of Mex- 

 ico, and that they are much more frequent, hence the effects more marked. 

 In the observations made by Rudolph Hering, Consulting Engineer for 

 the Chicago Drainage Commission, lie shows for one day not less than 

 seventeen oscillationsof over a foot in amplitude, and one of them exceed- 

 ing two and one-half feet. (See diagram.) 



le >9 lO Zl 27 23 24 



Fluctuations of the water surface of Lake Michigan, as recorded by an 

 Automatic Gauge, Chicago, 111., August 16, 1886. 



Note. — The wind was from the north-west in the morning and the 

 south-west in the afternoon. The lake here is sixty miles wide and from 

 twenty-five to fifty fathoms deep. 



Mr. Hering says : " The winds and barometric pressure produce a con- 

 stant oscillation of the surface, and at times a swinging motion from shore 

 to shore. * * * One oscillation on the above diagram is distinctly 

 recognizable as lasting about twenty minutes, which is the swing across 

 the lake. The greatest of these, as will be seen, was over two feet. The 

 oscillations are relatively greatest at the south end of the lake." 



Concerning these observed oscillations of the lake's surface, Mr. O. B. 

 Wheeler, an experienced Assistant on the Lake Surveys since 1862, who 

 was continuously employed upon these surveys for thirteen years, and 

 subsequently at intervals to date (1888), writes as follows : 



NOTES ON THE WATER-GAUGE RECORDS OP THE GREAT LAKES. BY O. B. 

 WHEELER, M. AM. SOC, C.E. 



"From my remembrance of the discussion of the self- registering tide- 

 gauge observations made at several points and for several years on the 

 Great Lakes, I olTer the following : 



"In these gauges the ordinary wind waves and waves from passing 



