JH's account of a comet reminds WT of a strange sighting many years ago. Comments further on improvements in photography, both those made and those needed.

Describes observing of comet that evening.

Comments on confusion between observing comet and zodiacal light. Extensive comments on various materials used in a photographic process where negatives change to positives over long time.

Suggests 'amphitype' as name for JH's process whereby same picture can go from negative to positive. Further comments on comet sighting, and on some improvements to Daguerreotype.

Zodiacal light is a real phenomenon. Further comments on negative to positive process. Questions whether WT can define one cometary orbit with two observations.

Comments on JH's positive calotype. Suggests comet may be return of (J.-D.) Cassini's comet of 1668. Gives theorem for finding parabolic orbit of comet if two observations are made in the ecliptic.