Thomas Jefferson Papers

Thomas Jefferson: Jefferson as a celestial observer, Ca. 1820, 1820

s. the sun—it’s altitude being about 23°  h.h. the horison—


tu, a complete horzontal circle of white light passing thro’ the sun.

a. a very bright and dazzling parhelion, not prismatic.

b.c. prismatic parhelia at the intersection of a circle a.b.d.c. whose radius was [. . .]° with the horizontal circle t.u.

x.d.v. an arch of an inverted circle having it’s centre apparently about the zenith. this arch was very strongly lined with the prismatic colors

k.e.l. an arch apparently elliptical rather than circular, e. being distant from the sun 26° the part included between x and v. was prismatic, the rest white. the space included between the two prismatic arches x.e.v.d. was made extremely brilliant by the reflection of the sun’s rays from innumerable minute spiculæ of snow floating in the Atmosphere.

q.f.r. a circle having a radius from the sun of 45° strongly prismatic about the points f.q.r. and faintly so all round.

m.n. a small arch of an inverted circle, strongly prismatic and having it’s centre apparently in the zenith.

rp.qo. arches of large circles very strongly prismatic, which could only be traced to p. and o.

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