168 
POPULAR SCIENCE REVIEW. 
interpretation which has been given to different stages will require material 
modification. The planet was moving over the star at the rate of about 
0"’3 per minute, so that the final disappearance of the star was well in 
accord, but the time at which the planet seemed to touch the star differs very 
materially, being 10 h o m 19 s with Mr. Ellery, about 10 h 6 m 0 s with Mr. 
White, and 10 h 7 m 0 s with Mr. Turner. This undoubtedly arises from the 
spurious disc given to the star and the spurious fringe given to the limb of 
the planet from the diffraction effect of the telescope. What was taken for 
the star seen through the atmosphere of the planet, was almost certainly the 
spurious disc of the star seen through the larger spurious fringe of the planet. 
Any effect really due to the atmosphere must have been completely masked 
by this effect, due to the spurious irradiation disc given to all objects by 
diffraction in the telescope. 
The occultation of a star by the planets has been frequently suggested 
as a method for determining the solar parallax, and were the phenomenon 
instantaneous it would be remarkably well suited for the purpose. Its great 
drawbacks are the infrequency of the phenomenon and the difficulty of 
observing the instant of the disappearance of the star at the bright edge of a 
planet. The present observation seems, however, to be rather favourable to 
the method, for the difference of the times of the observers from the mean, 
despite the very great difference in the instruments, is only — 0 s 'l, — 3 S ‘5, 
and + 3 8, 7, corresponding to a difference in the place of the star of — (F'OOOo, 
— 0"-0175 + 0"’0185, whilst the uncertainty in the parallax would give an 
uncertainty of ± 0"‘03. This is the only modern observation of the occulta- 
tion of a star by a planet, the last being one by Sir James South, nearly half 
a century ago. 
Star Systems. — Mr. Stone, F.R.S., the Radcliffe Observer, has recently 
drawn the attention of astronomers to a most interesting system of stars in 
the Southern Hemisphere, which seem to present a remarkable case of an 
apparent connection between stars widely distant from one another. 
Astronomers are familiar with cases of double stars, which seem connected 
together in some manner analogous to the Earth and the Moon. But these 
stars are very close to one another, being only separated by a few seconds of 
arc. In the present case the stars form an isosceles triangle, with sides 
nearly 20 degrees in length and with a base of over 30 degrees. This 
system of stars consists of two stars K 1 and £ 2 Reticuli , forming the apex 
of the triangle and scarcely as bright as the fifth magnitude ; £ Toucani, 
a fourth magnitude star at the southern base angle ; and e JEridani, a star of 
between the fourth and fifth magnitude, at the northern base angle. All 
four stars are invisible from England. Besides the apparent motion in Right 
Ascension and the North Polar Distance, which is possessed by all stars, 
astronomers have long recognized the fact that many stars possess a real, 
independent motion in space, which, though much smaller than their 
apparent motion, is still too large for its existence to remain in doubt. 
In general this proper motion, as it is called, amounts to only a small 
fraction of a second of arc per annum ; but in some few cases it 
amounts to considerably over a second of arc, or even to over two or three 
seconds of arc. In forming the Great Catalogue of Southern Stars, which has 
been the main work of the Royal Observatory at the Cape of Good Hope 
