84 On the annular Eclipse of the Sun 
In ail ruminating animals and birds of prey, there is a lucid 
tapetum at the bottom of the eye. 
The owl, that never sees the sun, has no nigrum pigmentum. 
The mackarel has the bottom of the eve lucid as quicksilver. 
The coup de soleil, met with in the West Indies, the effects 
of which I have seen, I attribute to the scorching effect of the 
sun’s rays upon the scalp. 
The Egyptian ophthalmia I consider to be the effect of the 
sun’s rays, and the glare of reflected light. 
I have stated the fact of the scorching power of the sun’s rays 
being destroyed when they are applied to black surfaces, but have 
not gone further. Sir Humphry Davy, to whom I showed these 
observations, immediately explained it. He said the radiant heat 
in the sun’s rays was absorbed by the black surface, and con- 
verted into sensible heat. 
VI. On the annular Eclipse of the Sun which will happen on 
the \5th of May 1836; being the principal Results of Cal- 
culations for Greenwich and Edinburgh. By Mr. GEorcE 
INNEs. 
Aberdeen, May 15, 1821. 
Sir, — Taz great solar eclipse of April 1, 1764, after four 
Chaldean periods, will return again on the 15th of May 1836. 
It will then be very great to all Europe, and in Great Britain it 
will be more interesting than any that has happened since 1793, 
as also than any that will happen before it. Like the eclipse of 
1793, it will be annular in Scotland, but not at Greenwich. 
The calculation of the general eclipse, the track of the central 
path of the annulus, its boundaries and extent, I shall reserve 
for a future communication, In the mean time, I send you the 
elements for projection and calculation, as also the results of the 
principal steps of calculations for Greenwich and Edinburgh. 
I once intended to send you the calculations at large, but after 
collecting the whole process into a quarto manuscript, I find that 
it could not be conveniently printed in octavo. 
In making a projection of this eclipse for any particular place, 
it will be found that the times and digits eclipsed may be deter- 
mined with almost as great accuracy as the method of projection 
admits of; the path of the moon, and those of the parallels of 
latitude, being nearly parallel to one another about the time of 
greatest obscuration ; whereas in that of September last, they 
iormed nearly the greatest angle possible. 
The following elements are obtained from the Solar Tables of 
Delambre, and the Lunar Tables both of Burckhardt and Burg. 
In calculating for Greenwich and Edinburgh, 1 have used the 
Tables of Burckhardt, The 
