SCIENTIFIC SUMMARY. 
423 
ciently brouglit into comparison with those of 1874. A comparison has 
indeed been instituted betwen the two transits in the ‘Monthly Notices’ 
for December 1868, wherein it is remarked that Halley’s method ‘fails 
totally for the transit of 1874, and is embarrassed in 1882 with the diffi- 
culty of finding a proper station on the almost unknown Southern continent.’ 
This statement, however, does not by any means accord with the results of 
my own investigation. On the contrary, I find that Halley’s method may 
be said to fail totally in 1882 ; while, as is now well known, I find (I may 
even say I have demonstrated) that HaUey’s method is the best of all 
methods depending on contacts, for 1874. If we assume, in fact (which I 
think will be generally admitted), that no station can be regarded as suit- 
able for Halley’s method where the difFerence between the actual duration 
and the mean duration is less than half the maximum acceleration or re- 
tardation, or where the Sun is less than 10° high at ingress or egress, then 
absolutely no station whatever is available in 1882, unless the south pole 
can be approached much nearer even than it was approached by Sir Jas. C. 
Ross in the famous expedition when Possession Island was discovered. I 
confess that the prospect of successful observation at Possession Island, with 
a Sun only 5° high at ingress, seems to me so slight that I should hear with 
regret of any attempt to carry out the suggested scheme for wintering at 
Possession Island in 1882.” 
Note on Jupiter in 1873. — Mr. Knobel, who has observed this planet with 
one of Browning’s 8-in. reflectors, remarks that this year “ the most striking 
feature has been the great change in the equatorial zone ; the port-hole 
markings, which were conspicuous at the previous opposition, have disap- 
peared, and long, irregular, broken masses, horizontal and inclined at a con- 
siderable angle to the equator, have taken their place. The north temperate 
dark belt, which has been previously depicted as single, is really a double 
belt, as in the drawings. On April 20th and May 11th the south tropical 
dark belt appeared thinned out towards the east. The south temperate dark 
belt has appeared of irregular width, widening towards the west ; atmo- 
spheric influences this year have been fatal to observations of colour ; but 
on May 11th, definition being remarkably good, the south tropical dark belt 
was observed of a brick-red tint, more decidedly red than the darker parts 
of the equatorial zone.” Mr. Browning remarks on the same subject : “ The 
colour of the equatorial belt of Jupiter was fading during the last weeks of 
the previous opposition ; during the present opposition the colour has been 
scarcely, if at all, perceptible ; there is a conspicuous absence of any intense 
markings on the surface of the planet, the copper-coloured belts being 
fainter than usual. Great changes have taken place in the fainter markings, 
and some of these with great rapidity. On several occasions the belts have 
appeared inclined at a considerable angle to the equator. During the whole 
of the opposition the definition has been so uniformly bad that I have found 
it useless to make drawings of the planet.” 
