154 Professor Denison Olmsted on the 



It ought to be remarked that the phenomena of this body 

 were particularly striking in the autumn and winter of 1837, 

 and the observations made this year shew a greater intensity 

 of light and a greater elongation from the sun. than those of 

 corresponding dates in 1835 and 1836. 



" Dec, 21, 1835. — This evening atmosphere very transpa- 

 rent; zodiacal light very conspicuous, reaching nearly to Alge- 

 nib though quite faint towards the vertex. Elongation 90°. 



" Dec. 28, 1837. — Night favourable ; appeared to me not to 

 reach quite so far eastward as it did a few nights since ; cer- 

 tainly not beyond the equinoctial colure ; could not be certain 

 much further than the pentagon of stars in Pisces. Elonga- 

 tion 75°. 



*• Feb. 7. — Zodiacal light very conspicuous since the last 

 moon, but has advanced eastward very little since Christmas, 

 still reaching only to Alpha Arietis. Elongation 75°. 



*' Feb. 24. — ^First night since the moon has been away ; sky 

 favourable for observation ; zodiacal light bright and well 

 defined, its axis nearly in the ecliptic ; reaches to the space 

 between Aldebaran and the Pleiades. Elongation 85°. 



" March 26.- — Zodiacal light very bright, reaching above the 

 Pleiades, which are a little north of the axis. Elongation 60°. 



" March 29. — Light more faint. Elongation 60°. Vertex 

 near the ecliptic. 



" April 6. — Light fading rapidly. Very diffuse. 



'* May 1. — Last night a very plentiful rain after a series of 

 warm days ; to-day air keen and sky very clear ; this even- 

 ing zodiacal light remarkably distinct (for this season of the 

 year), being discernible much nearer the horizon than com- 

 mon, and reaching further eastward among the stars than I 

 ever observed it before, namely, into the neighbourhood of 

 Castor and Pollux. Elongation 60°, but presumed to be much 

 greater than it would be, but for the extraordinary transpa- 

 rency of the atmosphere. 



'■^ May 10, 1834. — Zodiacal light seen for ten minutes after 

 twilight ceased — say till ten minutes after nine. Reached to 

 Castor, but very diffuse. Elongation 57°. 



" Seen no more in the west till the latter part of Novem- 

 ber." 



