1871.] Proceedings of the Asiatic Society. 131 
there appears the “black drop” 
of the observers of the Transit of 
Venus in 1769. At A in this 
figure I have endeavoured to 
give some idea of this phenome- 
non in an Annular Eclipse, and 
at page 16, Vol. XXIX, of the XK \ 
monthly notices of the Astro- \ XS ( \ 
nomical Society will be found \K ~ DW QN 
Some figures illustrating this in AX oS 
a Planetary Transit. When we are dealing with so thin a stratum 
surrounding the true Photosphere, we cannot see it in sunshine, 
as it is lost in the irradiation, (it may be partly visible in very 
large Telescopes where the irradiation is very small), and we 
are very apt to lose it at the moment when the sun disappears, for 
it is found only between the places where a moment before the 
Sun a Moon’s limb appeared, so that the observer following either 
of them might well miss it. 
In the search for, and verification of this important observation, 
the duration of Total phase can matter little. 
T have been in communication with the Home Secretary on the 
subject of observations of this Eclipse, and my views I may say 
have been most cordially received. I am not yet ina position to 
submit a proposition officially, but I have great hopes of being able 
to do so in a few days.* 
P. S.—I may just mention that in plotting the Shadow Track on 
a map it is necessary to allow for the error of its zero of Longitude, 
a precaution often forgotten. The Longitudes of the G. T. Survey 
require a correction of 3’-2”, 7”, and those of the Atlas of India one 
of 4’-11” to adjust them to the accepted Longitude of Madras. 
The President was very glad to learn from Col. Tennant that 
the Government is likely to sanction a scientific expedition to the 
Nilgherries on the occasion of the Total Eclipse in December 
next. The objects to which Col. Tennant proposed to direct obser- 
vation were, he need hardly say, of very great scientific interest 
and importance. The spectroscopic analysis of the Corona, so far 
* This has since been done, 
