340 



APPENDIX I 



In order to secure fixed data of reference, perma- 

 nent bench marks were established on the land, not 

 far from the igloos or tide staves. 



The ice-covering of the water nearly obliterated all 

 wind waves which generally impair the accuracy of 

 staff readings made in open bodies of water. The 

 measurement of the height upon staff of the surface of 

 the water, as the surface rose and fell in the well-holes, 

 was carried on with great precision, a fact which the 

 plottings of the observations have well brought out. 

 The observations were taken hourly; and during a large 

 percentage of the time these were supplemented by 

 observations taken more frequently, often at intervals 

 of ten minutes each. 



The chronometer used in connection with tidal work 

 was compared with true Greenwich time at New York 

 before and after the cruise to the Arctic. The com- 

 parisons showed that during this period of 461 days the 

 average daily gain of the chronometer was 2.2 seconds. 



The mean lunitidal intervals and the mean ranges 

 of tide, together with the approximate geographical 

 positions of the stations, are as follows: 



1 Results from Greely's observations, 1881-83, covering a period of nearly 

 two years. 



