REPORT OF THE SECRETARY. IT 



The corrections for referring each observation to the standard level were 

 taken from this diagram — no allowance being considered necessary for 

 a change in the variation of the mean level of the sea. All the observa- 

 tions properly corrected are given in a series of tables. From these 

 tables, another series was deduced, exhibiting in one view the apparent 

 time of high and low water, and the corresponding passages of the 

 moon over the meridian, its declination and comparative distance from 

 the earth. These latter tables were again plotted, and from the curves 

 thus produced it appears that the average time of the occurrence of a 

 series of 480 high waters at Van Rensselaer harbor was eleven hours 

 and forty-three minutes after the passage of the moon across the meri- 

 dian, corresponding to a mean declination of the sun and moon of 

 sixteen degrees. 



In like manner from 485 observations, the average time of low water 

 occurred seventeen hours and forty-eight minutes after the passage of 

 the moon over the meridian. The average interval of time between 

 the high and low water was six hours and five minutes. 



The tide wave at Yan Rensselaer Harbor may be considered as trans- 

 mitted from the Atlantic Ocean, and only in part modified by the small 

 tide originated in the waters of Baffin's Bay. This latter tide must 

 necessarily be small, since the direction of the long and comparatively 

 narrow bay is at right angles to that which would be most favorable 

 to the production of a disturbance of this kind. That the ocean tide 

 wave actually travels up along the coast of Greenland, or, in other 

 words, that it reaches Van Rensselaer Harbor from the south, is proved 

 by comparing the time of high water at different places along the west 

 coast of Greenland. 



Having the velocity of the tide wave along Baffin's Bay and Smith's. 

 Straits, the depth of the water may be approximately obtained. As- 

 suming the distance along the channel, between Holsteinborg and 

 Van Rensselaer Harbor, to be 770 nautical miles, the tidal wave has 

 a velocity of 202 feet in a second, which, according to Airy's table, 

 would correspond to a depth of about 1^300 feet. In the same manner, 

 by comparing the co-tidal hours at Upernavik with those of Van 

 Rensselaer Harbor, a resultant depth of nearly 4,800 feet is obtained. 

 These two may be considered as the limits of the depths in Baffin's 

 Bay and Smith's Straits. 



Besides the points noticed, several others are fully discussed in this 



paper. Among these is what is called the diurnal inequality, or the 



difference between the height of the two tides at the same phases of 



the moon, depending principally on her position with reference to the 



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