1866. | Astronomy. 81 
means of results for Occultation-correction for the Final Telescopic 
Semi-diameter in the four classes :— 
I. Disappearances of Stars at the Dark Limb: 
Mean from 130 occultations . . . .—1'"98 
No observations excluded. 
II. Disappeara es of Stars at the Bright Limb: 
Mean from 51 vecultations . . . .—0'"65 
Four observations excluded. 
ITI. Reappearances of Stars at the Dark Limb: 
Mean from 64 occultations . . . .—2'"32 
Ten observations excluded. 
IV. Reappearancés of Stars at the Bright Limb: 
Mean from 50 occultations . . . .+1'°38 
Eleven observations excluded. 
From the nature of the observations, the first and third of these 
means are very far superior to the second and fourth, and the first 
is greatly preferable to the third. We cannot be sensibly im error 
in saying that the moon’s Occultation Semi-diameter is less than 
the moon’s Telescopic Semi-diameter by 2'°0. 
Mr. De la Rue, from his photographs taken during the eclipse 
of 1860, obtained the following corrections to the Telescopic Semi- 
diameter :— 
By the differences between observed and tabular dis- 
tances of centres, deduced from the measure- 
ments of peripheries, and of the measures of 
cusps of all the photographs. . . . . .—2'1 
By the times of first and last contact, deduced from 
the measurements of the distances of the peri- 
pheries in the photographs taken near these 
Ct, hs a SWS i) SDE ICG. WAL ADRES 
By the times of first and last contact, deduced from 
the measurements of the distances of the peri- 
pheries and of the cusps in the photographs 
taken near theseepochs. . . . . . .-1'"0 
Mr. T. Fletcher, of the Tarnbank Observatory, has drawn the 
attention of those astronomers who are in possession of large tele- 
scopes, to the present condition of that most remarkable star ¢ Her- 
eulis. With his large refractor of 94 inches aperture and a power 
of 1,000 it is absolutely single. A few years ago, he had no diffi- 
culty in measuring it both in position and distance with a telescope 
of 4 in. aperture only. As the companion star is undoubtedly close 
upon its perihelion, the earliest possible observation of its reappearance 
will be of great value in the determination of its orbital element. 
Mr. Dawes states that ast year he found the star quite single. 
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