( 606 ) 
which furnished 0.27264 for the proportion of the mean moon’s semidia- 
meter and that of the earth’s equator (at least this is the result of the 
occultations discussed). After mature consideration, however, I now 
adopted the value 0.2725 hor. equ. parallax + 0"04, This leads 
approximately to the same value as when we take the sine of the 
moon’s apparent semidiameter 0.272525 of the sine of the equatorial 
horizontal parallax. 
This factor is the mean of those which were derived from occul- 
tations during total eclipses of the moon by Lupwie Srruve in 1888 
and by J. Perers in 1895 (0.272535 and 0.272518). The Nautical 
Almanac, which used both the semidiameter and the parallax as given 
in the Tables of Hansen, gave a value larger by 1'4 to 1"6. This 
difference has remained the same up to the present time. 
About the observed occultations we may communicate the following 
particulars. They were mostly observed by myself, partly with the 
Fraunhofer telescope, (aperture 11 em.) mounted on a stand, which 
Mr. Stoop of Amsterdam had kindly lent to the commission for the 
observation of the transit of Venus, partly with the telescope of the 
heliometer (aperture 7*/, em.). At a later epoch, when the assistance 
of Mr. Ernst BAKHUYZEN was not so constantly required, as in the 
beginning, for the experiments of Dr. Kaiser with the photoheliograph, 
he also took part in the observation of the occultations, as also 
did Mr. Sorrers in one case. 
Altogether 35 disappearances and 4 reappearances were observed ; 
but 12 disappearances and 1 reappearance had to be rejected. There 
thus remained 23 disappearances and 3 reappearances, that is al- 
together 26 observations, which furnished useful results. 
The reason of the rejection lay partly in the fact that, already in 
recording the observation, the remark “uncertain” had been added, 
an addition due to the faintness of the star as it approached the 
moon’s limb, or to passing clouds. 
For another part the correction of the longitude determined by 
GrrMAIn and adopted by myself, came out so extravagantly large 
that some mistake or other seemed probable. There seemed to be 
reason to suspect that a wrong star had been taken for the oeculted 
one. In five of the cases I succeeded to find out the right star by 
means of star catalogues, but in four other cases all my endeavours 
proved in vain. Ultimately there remained five cases in which 
the correction to the adopted longitude was found so considerable 
(— 215, 20s, —28s, 24s and ++ 338), that there was no escape 
from the conclusion that either a mistake, however improbable in 
itself, had been committed in writing down the time, or that the 
