. Appendix [to] Captain Parry's journal [of a] second voyage [for] the discovery of a North West passage from the Atlantic to the Pacific [microform] : [performed in] His Majesty's ships Fury and Hecla, [in] the years 1821-22-23. Science; Botany; Sciences; Botanique. 180 MR. FISHER ON ATMOSPHERICAL REFRACTION. 'li \ M i l!l'i. number of observers, and instruments employed, and also the number of evenings in which the observations were made; for those made at different periods are to be preferred to a greater number when confined to a fewer number of times of observations, as the results clearl
. Appendix [to] Captain Parry's journal [of a] second voyage [for] the discovery of a North West passage from the Atlantic to the Pacific [microform] : [performed in] His Majesty's ships Fury and Hecla, [in] the years 1821-22-23. Science; Botany; Sciences; Botanique. 180 MR. FISHER ON ATMOSPHERICAL REFRACTION. 'li \ M i l!l'i. number of observers, and instruments employed, and also the number of evenings in which the observations were made; for those made at different periods are to be preferred to a greater number when confined to a fewer number of times of observations, as the results clearly shew. In Table II. are given the results of the observations of each observer, made between the altitudes of 4 and 5 degrees, which are selected as they principally consist of observations upon Sirius when on or near the meridian, and therefore, were made under somewhat more favourable circumstances than the rest; and also for the sake of comparison with my own meridian observations upon Sirius, with the repeating circle at the same altitude. It appears upon the whole, by seven hundred and ninety-seven observations, made by eight diflferent observers with sextants, at the height of about fourteen feet above the frozen sea, that at the apparent altitude of 4° 22' 54", thermometer -33°.2, bar. , the refraction is 13' 39 ".4, whereas by my own observations the refraction is 7". 7 less; which is as near an agreement as could be expected, considering the great differences between the results of the sextant observations. The rapid increase in the refraction as the altitudes diminish is very remark- able; and, in consequence, the great distortions of the sun's disc when near the horizon are very great, the lower limb appearing perfectly flat, and the upper part of an elliptical shape, but of a jagged and broken appearance, having over it often a kind of tuft or crown, detached from that v/hich would appear under usual circumstances to be the upper limb; but fro
Size: 1062px × 2353px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, booksubjectbotany, booksubjectscience, bookyear1
