46 ASTRONOMICAL OBSERVATIONS TX THE ARCTIC SEAS. 



Nov. 2, 18.53. "A star observed at 2 P. M., and on tlic following day at half past one o'eloclv; 



on the 4th the thermometer had to ))e read by means of a lantern at 3 P. M., and on the fol- 

 lowing day at 2 P. M." 

 Nov. 1, 1853.— "Observed the first faint streak of daylight at G A. M. On the following day, stars 



of the 2d magnitude were visible at noonday; on the 2d instant, Capella had been seen at the 



same hour, and but for the misty haze probably earlier." Polaris was seen at noou on the 10th. 

 Nov. 22, 1853. — "The darkness is now (nearly) complete, being barely able to read at noonday." 



Sun's centre below the horizon 8° 09' (temp. — 35°). 

 Dec. 22, 1853. — Maximum depression of the sun's centre below the horizon at noon 11° 23'; temp. 



—35°. 

 Jan. 4, 1854. — "To-day at noon a distinct zone of illumination was seen to the south clearly defining 



the highest hills. This is the first departure we have had from our uniform darknes.s. The 



largest print is illegible at noon." Sun's centre below the horizon 10° 41' (temp. — 11°). 



On the following day, the first appearance of twilight was noticed at 7 A. M. ; on the tth and 



18th, the largest print was not yet readable at noon. 

 Jan. 19, 1854. — "To-day at noon read the title page of my prayer book by turning the type towards 



the illuminated sky to the southward." Sun's centre below the horizon 8° 11' (temp. — 51°.) 

 Jan. 20, 1854. — "A faint appearance of brownish-red appeared above the hills to the southward 



between 11 A. M. and 1 P. M." On the 22d the standard thermometer could be read at noon 



without a lantern, and on Feb. 3, at 9 A. M. 

 Feb. 13, 1854. — " The light at noonday had a decided yellow tinge." 

 Feb. 20, 1854. — "At noon saw the sun's rays shining on the cliffs on the eastern side of the bay." 



Astrtmomically, the sun's upper limb should reappear on the horizon on the 16th. On the 2d 



and 4th of March twilight appeared at 3 A. M." 

 March 26, 1854. — " The standard thermometer is read at midnight without artificial light. On the 



30th, stars of the 2d magnitude still visible at 1 A. M." 

 Oct. 29, 1854.— "The red of the graduated zone of sunset is deep cherry-red, running into crimson, 



which, after being cut by bluish -gray strata, blends with the higher blue by rosy pink." 

 Nov. 15, 1854. — "Can read type in Parry's Narrative at noon, but with great diificulty." Sun's 



centre below the horizon 6° 25' (temp. — 35°). 

 Nov. 19, 1854. — "At noon cannot read PaiTy's type." Sun's centre below the horizon T° 26' (temp. 



—14°). 

 Dec. 31, 1854. — "The twilight was remarkably apparent at noon to-day." 



For comparison with the above, the following information has been extracted 

 from Gehler's Physical Dictionary: In latitude 51°, Brandes was able to read the 

 largest type, with the book turned toward the light, the sun's centre being 102° 

 below the horizon; ordinary large type was read with the sun's depression of 82°. 

 At Van Rensselaer Harbor, in latitude 78*, the limits of legibility, for ordinary large 

 type, were with a depression of 7° 26' and 8° 11'. It is generally assumed that, in 

 temperate latitudes, complete darkness sets in when the sun's depression reaches 

 18°; on the 2d of March, the first appearance of twilight was noticed at a depres- 

 sion of 15° 0' (temp. — 37°) in latitude 78i; thus it appears that in this high lati- 

 tude twilight is more feeble with the same depression of the sun than in lower 

 latitudes. This circumstance is, doubtless, owing to the diminished height of the 

 atmosphere (by contraction, on account of the cold, and by compression) in these 

 hii^h latitudes. 



