125 



Hourly observations of the height of the tide and of the barometer 

 were commenced on the 1st of November, and were continued by 

 the officers of each ship throughout the whole of the nine following 

 months to the end of July. After forty- seven days of observation 

 an interruption in one of the series occurred in consequence of the 

 tide-pole of the " Enterprize" having been drawn up by the ice, to 

 the under part of which it had become frozen. The amount of dis- 

 placement of the pole was easily determined by a comparison with 

 that of the " Investigator," but several days elapsed before it could 

 be satisfactorily fixed at the same point in which it had been origi- 

 nally. The observations of these forty-seven days are those which 

 are given in the paper, and their discussion is the immediate object 

 of the communication. 



It is stated that subsequent observations seem to show that, from 

 the time of the interruption to the middle of July, there was a pro- 

 gressive elevation of the mean level of the sea, which, although of 

 small amount, was sufficiently evident from month to month to 

 render the subdivision of the series desirable, in order that the indi- 

 vidual observations of each separate division should be strictly com- 

 parable. 



The height of the sea and the corresponding height of the mer- 

 cury in the barometer, at every hour in each day, from the 1st No- 

 vember to the 18th December 1848 are given in tables. In these 

 the arithmetic mean of the hourly heights of the sea for each day is 

 taken as the mean level of the sea for that day, and the mean of 

 the hourly heights of the barometer is taken as the corresponding 

 height of the barometer. These mean levels and corresponding 

 mean barometric heights are given in another two-column table, 

 arranged in the order of the days of observation ; and in a third 

 table these are arranged in the order of the heights of the barometer 

 with the corresponding mean levels, without regard to the dates of 

 observation, for the purpose of showing the dependence which the 

 latter have on the former. 



On these tables the author makes the following remarks. The 

 forty-seven days of hourly observations give for the mean height of 

 the barometer 29- 874 inches, and of the mark of the mean level of 

 the sea 21 feet 0'2 1 in. 



