ee ee ee 
~* 
“i 
THERMOMETRICAL OBSERVATIONS AT POINT BARROW. 165 
the end of October and April, or about 24 to 30 days after the equinoxes ; 
the extreme of cold was experienced in the first part of February, and the 
ae of summer heat was probably about the end of the first decade of 
ugust. 
The usual interruption to the winter cold was less decided, and took place 
at the beginning of the second decade of January, raising the mean of that 
month above December, as December in the preceding season had been 
raised above November. 
Taste VIII. corresponds to Table II. By it the range between the 
highest and lowest single temperatures will be seen to be 1 degree more than 
the previous year, and give a mean 3 degrees below the true one of the year, 
whilst the means of the daily extremes accord very nearly with it. The 
greatest monthly range took place in March, and was 65 degrees: 11 less 
than that of April of the preceding year, and 31 less than the annual range. 
Tasxe IX. is similar to Table I[I., from which it presents no very re- 
markable difference. In it April again shows the most marked range between 
the day and night extremes, amounting to more than 123 degrees. 
Tastes X., XI. and XII. agree in their general features with Nos. IV., 
V. and VI., and are defective in the July and August columns from the 
absence of the ship. 
The succeeding Tables are compiled to give the means of two years, for 
which purpose the observations for the omitted summer intervals have been 
intercalated. ; 
Taste XIII. gives the means of the decadesor third parts of each month, 
and of the whole month. Also, the highest and lowest single temperature 
noted during the two years, the extreme thermometric range being 97 de- 
grees. The mean of these two extremes was+3%5, and the true mean of the 
two years was + 6°°882, or 25 degrees below the freezing-point of water. The 
autumnal and vernal periods at which these temperatures occur, by this Table, 
are about 14 and 23 days after their respective equinoxes; but the extremes 
of heat and cold, which occur on the 8th of August (probably) and on the 
8th of February, are more than double that number, or about 48 days, after 
the solstice. Here the interval between the summer extreme and the occur- 
rence of the annual mean in autumn is 67 days, and from the latter to the 
time of the winter extreme is 117 days; from the winter extreme to the 
vernal period at which the annual mean occurs is 74 days, and from this to 
the summer extreme 107 days. 
TasLe XIV. gives the mean temperature for two years, of every hour for 
each month. ; 
TaBLeE XV. gives the mean of every pair of similar hours of Table XIV. 
TaBLeE XVI. gives the mean temperature for two years of every hour for 
each of the four seasons, for the half-years, and for the year. In this Table 
it will be observed that the interval of time between the extremes and that 
at which the annual mean following takes place is perceptibly shorter than 
between either extreme and the time of the mean preceding it. 
Tas Le XVII. gives the mean of every pair of similar hours in Table XVI. 
Tas_e XVIII. gives the mean temperature of every hour for the month of 
June, for 22 days in July, and for the 21 days both before and after the 21st 
of June, from hourly observations taken with a blackened thermometer ex- 
posed to the sun’srays. This Table, though so limited, may be of some in- 
terest in regard to the growth of vegetation during the short summer of the 
Arctic regions. 
Tas_e XIX. gives the means of the pairs of similar hours in the first and 
third columns of Table XVIII. 
