TOTAL SOLAE ECLIPSE OE JULY 18, 1860. 
395 
These numbers agree very closely with the theoretical numbers, the chief difference 
being in the epoch of the end of the eclipse, which is earlier by 7 seconds than Mr. Cae- 
EES'’GTO]N'’s computation, and by 6' 8 seconds than that of Mr. Faelet. 
The following are the differences : — 
De La Eue— Carrington. 
sec. 
First contact 
Last contact 
Duration 
Middle of eclipse 
Nearest approach of centres 
Direction of motion of the moon’s centre dming 
the totality 
Kelative motion of the centres per minute . . 
Position-angle of the line joining the centres at 
the first contact •. 
Ditto at the last contact 
+ 1-7 
-7-0 
-8-7 
+1-2 
— 1*2 
-7' 
-fO-34 
+ 2' 
- 8 ' 
De La Eue— Earley, 
sec. 
-fO-7 
- 6-8 
-7-5 
-j-0’7 
+0-26 
+ 2 ' 
— 6 ' 
The periods of first contact, and the middle of the eclipse, are accordant, but not so 
that of the end of the eclipse, the duration being less than the computed duration by 
8 seconds. The half of this, or 4 seconds, would correspond to a distance moved through 
of l"-9, by which quantity the radii of the moon and of the sun jointly would be 
smaller than the computed values. Without any desire to attach more importance to 
the results of the photographic measurements than they merit, I believe that I have 
made out satisfactorily that astronomical photography is capable of furnishing data on 
which great reliance can be placed, and which it would be difficult to collect in any 
other way. It possesses the advantage, in the case of sun-pictures, of instantaneous 
registration, and permits of measurements being made calmly and at leisure, and of their 
being repeated as often as may be considered desirable. Its employment in connexion 
with means of measurement wiU rmdoubtedly suggest future improvements ; and although 
it is impossible at present to predict the destiny of astronomical photography, it appears 
likely that it will take a high rank among the methods of observation. 
Solar Sjpots. 
With the view of ascertaining whether any connexion exists between the luminous 
prominences and the faculee, or the spots on the solar disk, photographs of the sun were 
obtained as soon as the heliograph could be got to work, and others would have been 
taken on each day previous to the eclipse if the weather had proved favourable. Several 
photographs were secured on the 14th, but only one on the 16th, which was not 
measured, having been overlooked ; spots a and T) were then well on the solar disk. 
Afterwards, until the 18th, none could be procured, but on the 19th and 20th several 
were obtained. With the exception of a spot which became visible on the 20th, with 
