BULLETIN OF THE NATURAL HISTORY SOCIETY. 
Of course the feature of most immediate scientific interest 
in this table concerns its possible testimony as to changes or 
riuctuations in climate. With this in view, I have carefully 
plotted these dates in parallel graphs, hoping that some general 
fact or princii:>le might thereby stand revealed. Nothing 
very positive, however, has resulted, and the possible inferences 
are vitiated by the probable errors of the table, which are of two 
sorts: — first, misprints in figures, and second, a possible or 
probable difference of method at different periods in deciding 
upon what constitutes the opening or closing of navigation. 
Thus, the arrival of the first steamboat appears to be taken 
usually as marking the opening of navigation, but it is* quite 
likely that competition of competing lines, or other condi- 
tions of traffic, differing at different periods, might lead to a 
prompter pursuit of the ice by the steamers in some periods 
than others; and the date of closing is even more liable to such 
variations. Besides, the ice often moves after once having 
closed the river, thus allowing another possible difference in 
method of computation."^ Nevertheless, despite its errors the 
list has its value, which will increase with time and any cor- 
rections that can be made therein. 
While I can find in the graphs and figures no basis for any 
generalization of importance, they do show two facts. First, 
the average time the river is open is a little longer in the second 
than in the first half of the list; and second, the earliest dates 
of opening and latest dates of closing of navigation fall in the 
later years. This slight indication of some amelioration of 
climate, however, may be vitiated by some of the errors men- 
tioned, or even may be simply an accidental accompaniment 
of the smallness of number of the figures. 
♦These later movements of the ice are recorded in the table given for the years 1825 to 
1849 in the New Brunswick Almanac for 1850, prepared by the Fredericton Athenaeum, 
page 125. 
