RECORD AND REDUCTION OF THE TIDES. 



The observations and discussion of the tides at Van Rensselaer Harbor, tlie 

 winter quarters of the Advance during 1853-54 and 1854-55, will form the last of 

 the series of papers on the results of the expedition, prepared by me for publication. 



Occasional tidal observations were made after passing Smith Straits, when, 

 owing to the peculiar navigation through the narrow openings between the coast 

 and the bay ice, the vessel was much exposed to the tidal action, frequently 

 grounding at low water, and otherwise, by taking advantage of high tides, slowly 

 advancing to her winter quarters. 



The bay, near the head of which the Advance was laid up, and used as the 

 winter quarters by Dr. Kane's party, is freely exposed to the north (true) and 

 northwest; the indentation of the shore line is about five miles; some rocky islands 

 are situated within the bay. 



Shortly after the vessel entered the harbor a tide staif was arranged, and a 

 series of tidal observations was commenced on September 11, 1853, and continued, 

 with occasional interruptions (partly owing to defects in the pulley-gauge, after- 

 wards rigged up, and partly owing to other unavoidable accidents) till the 24th of 

 January, 1855, on which date the regular log book appears to have been discon- 

 tinued. 



The several series of observations during this period are of very unequal value, 

 as will appear in the detailed examination and discussion of the results. The 

 difficulties to be overcome in the attempt to secure a reliable set of observations 

 were considerable, those of a physical nature being the greatest. The observations 

 with the staff or sounding line are subject to irregularities from a slow movement 

 of the vessel, which, though imbedded in ice during the greater part of the year, 

 is yet not stationary; these observations may also be affected by the softness of the 

 bottom; the observations by means of a pulley tide gauge may be defective, on 

 account of a slow drift of the vessel and motion of the ice field, also in consequence 

 of a lengthening or shortening of the rope, or it may be in consequence of slipping 

 of the rope on the circumference of the wheel. The latter defect, or one similar 

 in its nature, has been a source of much annoyance, requiring the application of 

 corrections to the readings, in order to refer all observations to the same zero of 

 the scale. There is another defect to which pulley-gauges are subject, namely, the 

 gradual rise of the vessel, in consequence of the consumption of provisions and 

 fuel. Notices of these defects will appear in the subsequent discussion. 



The pulley-gauge is described by Dr. Kane, in volume I of the Narrative, p. 

 117, as follows: " Our tide register was on board the vessel, a simple pulley-gauge, 

 1 



