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graphic appliances in 1882, if only suitable southern stations 
can be occupied for the purpose ; and, as no other method is 
available, except the demonstrably untrustworthy Delislean me- 
thod, we can scarcely doubt that an effort will be made by the 
scientific nations to overcome the difficulties which will cer- 
tainly present themselves in the search for and occupation of 
stations in the southern hemisphere. The nature of these 
difficulties will be at once recognised from fig. 3, which shows 
where are the best stations of all. It will be seen that in the 
Fig. 3. 
Sunview of the Earth at the middle of the Transit of 1882. 
northern hemisphere there will be an enormous extent of 
land-surface where the parallactic displacement will be great 
(exceeding half the maximum at stations on the northern side 
of the northern line, marked 5), and the solar 'elevation suffi- 
cient (exceeding 20° at stations within the circle marked 20°). 
But the corresponding southern region is, in the geographical 
sense, most unfavourably placed. It is indeed precisely in the 
heart of this region that the title is placed, in Mercator’s 
