170 The Late Transit of Venus. [April, 
near the beginning or end of transit, or near the middle of 
her chord of transit ; and observations of external contacts, 
either at the beginning or end of transit, come under the 
head of Delislean eperations, while the observation of the 
interval of time between the two external contacts is a 
Halleyan operation. But also the Halleyan and mid- 
transit methods can be considered together, because all 
good Halleyan stations are good stations for observing mid- 
transit. Let us take the classes in the order indicated, viz., 
first, the Delislean; secondly, the Halleyan. 
Speaking generally, it may be said that the English scheme 
was the only one which made direct provision for Delisle’s 
method. Originally, as most persons know, the idea was that 
no other method was available at all; and, accordingly, we 
find not only that our official folk invited England to 
provide exclusively for Delisle’s method, but assigned to 
other scientific nations their Delislean parts. Russia was 
to fortify the region for observing earliest ingress (around 
the point 1 in the plate), and France also was to provide sta- 
tions for this phase, England occupying the Sandwich Isles 
(aided perhaps by an American party there, and another at 
Tahiti, unless it so chanced that America reserved her 
strength for the transit of 1882, her share in which was also 
assigned her by our official astronomers). France was to 
strengthen the forces near 1’, the region where retarded 
ingress was to be observed, though here again England 
undertook the chief part. For the region around E’, where 
egress occurred earliest, England made herself entirely 
responsible; and, lastly, she undertook to occupy Alex- 
andria, leaving to Russia the provision of stations on 
Russian territory around g£, the place where egress occurred 
latest. 
If this programme had been carried out, England would 
have reaped the chief honours, always supposing that the 
plan of operations had been justified by the actual conditions 
of the proposed work. England would of herself have made 
sufficient provision for applying Delisle’s method, both at 
ingress and at egress, other nations taking only a subordinate 
part in the arrangements for either phase. Of course, if it 
had been discovered after the event that the proposed plan 
of operations took no account of at least one-half the chances 
of success, and left regions unoccupied which were even 
more important than those considered in the English official 
programme, England would have reaped something far 
different from honour. Other nations might then have been 
able to say that trusting in the unquestionable skill and 
