Dec. 21, 1882 | 
These accelerated egress contacts were made, roughly, 
about 7h. 47m. Greenwich mean time. 
Corresponding to these, we have for the phase retarded 
egress the New Zealand observations and the observa- 
tions by Ellery and his staff at Melbourne. The observers 
at New Zealand were Lieut.-Col. Tupman, R.M.A., and 
Lieut. Coke. The internal contacts must have been 
made about 8h. om. 30s. G.M.T. 
Observations of this phase which were secured by Mr. 
Ellery and his assistants at Melbourne must have been 
made about 8h. 1m. 30s. G.M.T. 
The failure of the Brisbane observations through clouds 
and the partial failure at least of the Bermuda observa- 
tions at egress have considerably weakened the weight 
of the determination of the sun’s distance from the egress 
observations. But the observations secured with the 
large available difference of time of about 84os. should 
most certainly give a determination of the sun’s distance 
from the egress observations alone with an error less than 
500,000 miles. 
Besides the above observations, Capt. Wharton, 
H.M.S. Sy/via, has been provided with two good tele- 
scopes; and, if the weather has been favourable, will 
have secured observations both of the ingress and egress, 
having established himself at some station on the South 
American continent, not far from the Falkland Islands. 
The Greenwich mean times of internal contact at Capt. 
Wharton’s station may be taken at about 2h. 15m. at 
ingress, and 7h. 52m. at egress. The computed times for 
the contacts at Capt. Wharton’s station would be but 
little affected by any error in the assumed mean distance 
of the sun, but they are influenced as much as the other 
stations by any error in the assumed distance between 
the centres of Venus and the sun at which the contacts 
take place. Observations, therefore, at such a station 
are of importance as a check upon the results obtained 
from the comparison of results from stations of greatly 
accelerated and retarded phase. 
The longitudes of stations in Jamaica and Barbadoes 
have already been connected with Greenwich through 
Washington by the American observers by means of 
telegraphy. Lieut. Neate has determined the longitude 
of Bermuda through Washington, by the conveyance of 
chronometers between Bermuda and New York, where 
Washington time is available. Arrangements have been 
definitely made for Lieut. Darwin, R-E., to connect Port 
Darwin with Singapore, and thus the telegraphic longi- 
tude of the Australian and New Zealand stations, which 
have already been connected together, will be deter- 
mined. 
The longitude of the Madagascar station has been 
determined by the conveyance of chronometers between 
Durban, in Natal, and Madagascar, the sea rate of the 
chronometers being ascertained by their rates during the 
voyage between Durban and Cape Town. 
It will be seen, therefore, that there will be no difficulty 
in the discussion of the observations from the want of 
accurate knowledge of the position of the observing 
stations. 
The observations of the British Expeditions have been 
made by observers of skill, with excellent instruments, 
under approximately similar conditions of illumination 
and with sufficient optical powers. ‘he observers have 
all been trained to observe the same kind of contact, and 
that one of so distinctive a character that no dou ts about 
the time record whick refers to the kind of contact 
required for comparison with those made at other stations 
should be possible. This point is one of the utmost im- 
portance. In all attempts to determine the sun’s distance 
from these contact observations we have to assume that 
the “contacts observed” took place with the same 
angular separation of the centres of Venus and the sun 
as seen from the observers’ position on the earth’s sur- 
face. There is no reason whatever why this assumption 
NATURE 
179 
should be true unless the “contacts observed” are con- 
tacts of the same class. There is an interval of more than 
2om. between the “ external contact” at a station and the 
“internal contact” at the same station. If, therefore, 
any one should combine the time of external contact at 
one station with the time of internal contact at another 
station, without allowing for the motion of the earth 
and Venus, in the interval of about twenty minutes he 
would obtain a startling but very erroneous result for the 
sun’s distance. The error thus indicated would, how- 
ever, differ nothing in kind, but only in degree from those 
which have, to some extent, unfortunately, brought this 
method of contact into doubt. 
The success of the British observations, particularly 
at ingress, has, however, been so complete, that the 
method of contact will now have a fair trial. 
I await the result with perfect confidence. Neither the 
method of contact nor any other known method can, with 
our present instrumental means, settle the sun’s distance 
to a hundred thousand miles. But the extreme range of 
possible uncertainty, as shown by the difference between 
the results obtained from Mr. Gill’s heliometer measures 
of Mars east and west of the meridian at the opposition 
of 1877, and those obtained from the differences in North 
Polar distances between Mars and stars on the meridian 
as observed at our principal northern and southern obser- 
vatories at the oppositions of 1862 and 1877, is about 
1,700,000 miles. All our other recent determinations, 
which have stood the test of examination, fall within 
these limits, and do not generally differ much from 
92,000,000 miles. The contact observations of the British 
expedition will, I feel confident, fix the true distance, 
without any greater error than 300,000 miles, and should 
settle the question whether either of the extreme values 
mentioned can be the true distance, or whether their 
mean is not much nearer the truth than either of them. 
E. J. STONE 
We have received the following additional communica- 
tions on the transit :-— 
THE observation of the transit of Venus here to-day 
was attended with a remarkable, and I think hitherto 
unnoticed phenomenon. 
When the planet had entered nearly one-half its 
diameter on the solar disc, its contour was _ barely trace- 
able outside by the faintly luminous line of light noticed 
by previous observers. But in addition to this a spot of 
light extending through nearly 30° of the planet’s circum- 
ference, and from its periphery zzwarvds for about one- 
fourth of the radius was distinctly seen. The brightness 
appeared greatest at the outside, and faded toward the 
centre. This appearance was noted by me through the 
great equatorial, by the aid of a polarising eye-piece, and 
a magnifying power of 244. The position-angle of the 
bright spot was approximately 178°, as estimated by me 
(for, owing to the fact that the polarising eye-piece has 
no position-circle, only an estimate was possible). 
At the same time an assistant (Mr. J. E. Keeler), ob- 
serving with a telescope of only 2} inches aperture and a 
power of 70, was able to see the same bright spot quite 
independently, and estimated its position-angle at 168°. 
The position-angle of the planet itself on the solar disc 
was approximately 147°. The bright spot was therefore 
distinctly on one side of a line passing through the centres 
of the sun and Venus. 
The observation was repeated at intervals through 
passing clouds for seven or eight minutes, and whatever 
may be its interpretation, of the fact of observation there 
can be no question. 
There would seem to be no analogy between this very 
peculiarly disposed and definite bright spot upon the 
planet’s edge, and the small central spots described by 
