March 11, 1887.J 



SCIEJSrCE. 



247 



Grinnell Land, and a casual observation of high 

 water at the head of Greely Fiord, during the 

 progress of the readings at Fort Conger, with a 

 dozen or more high and low waters noted during 

 the retreat through Kennedy Channel and Kane 

 Basin. The original records, too bulky for easy 

 transportation, were Jeft stored at Fort Conger 

 when the party abandoned that station ; but close 

 transcripts, previously prepared and carefully 

 verified, were brought away by Lieutenant Greely, 



at stations beset with heavy ice, even short series 

 are, as a rule, sadly out of joint and comparatively 

 worthless. Unless the stability of the gauge is 

 absolutely assured, which can seldom be the case, 

 only frequent resort to levels between the gauge 

 and one or more permanent bench-marks on shore 

 can insure scientific value to the observations. 

 At Fort Conger the observations of the first year 

 depended in this respect upon a gauge that seems 

 to have been stable, those of the second upon 



^3 if 5 6 7 8 S 10 11 IS 13 14 15 16 



Fig. 11. — Two groups, of ten thousand words each. Atkinson, : Mill, . 



and on his return to this country referred to the 

 superintendent of the coast and geodetic survey, 

 and later were placed in the hands of Mr. Alex. 

 S. Christie, chief cT tne tidal division of the office, 

 for reduction and di. cussion. 



The weak point of tidal observations is almost 

 invariably, even in middle latitudes, the instability 

 of the staff and the undetermined fluctuations in 

 altitude of the staff zero ; so that it not infre- 

 quently happens that a satisfactory reduction of 

 all the observations to the same plane of reference 

 is a wholly intractable problem. In high latitudes. 



series of spirit-levels. Only two months of the 

 series were in much doubt, and a tolerably satis- 

 factory adjustment of these was finally effected. 

 The observations bear abundant internal evidence 

 of a conscientious and persistent endeavor to se- 

 cure trustworthy and precise results ; and, although 

 they are far from equalling observations of stand- 

 ard excellence in middle latitudes, they are be- 

 lieved to constitute the longest and best series ever 

 brought back from the arctic seas. 



Following are some of the results of a non-har- 

 monic analysis of the observations at Fort Conger : 



