1900 - 1 .] Mr Thomas Heath on Photographs of the Corona. 397 
photograph as a picture of the Corona. I regret to say that, owing 
to the amount of light in the sky during the whole progress of the 
total phase, the two longer-exposed plates show more or less 
fogging of the background, making it rather difficult to obtain 
good prints. This is more especially the case with No. 3, which 
had the longest exposure. 
The instrument with which the photographs were obtained is an 
equatorially mounted telescopic camera, belonging to the Royal 
Observatory, Edinburgh, with a Cooke triple object-glass of 6-inch 
aperture and 104 inches focal length. The object-glass had been 
only recently acquired by the Royal Observatory when the eclipse 
took place. It had, however, been mounted sufficiently long to 
allow of its being carefully tested by Professor Copeland, who con- 
cluded that it was admirably suited for such a purpose as photograph- 
ing the Corona. A few trial photographs were also made for the 
purpose of determining the focus, and at the same time testing the 
photographic definition. Amongst others, the trail of the double 
star £ Ursse Majoris was photographed. On developing, the 
trail was found to be distinctly double in all its length. The 
difference of declination of the two components is 1 2"*6. If we 
compare this with the moon’s angular diameter and her diameter 
measured on the eclipse plates = 0*94 of an inch, we will find the 
distance between the two trails to be of an inch. 
It will be seen from the photographs that the whole of the 
moon’s disc is surrounded by coronal light, but that the rays 
about the sun’s polar regions are very much shorter than those 
which emanate from the regions about the equator, the usual form 
of Corona at minimum of sun-spots. 
The long streamers stretching out to the east and west occupy 
about 135° of the limb on each side, and are nearly symmetri- 
cally placed with reference to the sun’s equator. The two 
sides, however, present quite different configurations, in their 
outermost extensions more especially. The western streamer has 
its longest extension at the sides, which reach outwards about a 
solar diameter and a half, as measured on photograph 3, the 
northern edge being somewhat longer than the southern. These 
edges start from the limb in beautifully curved lines for about half 
their length ; the outer halves, on the contrary, are straight and 
