W. Huggins—Photographing the Solar Corona. 27 
Art. V.—On Photographing the Solar Corona without an 
Eclipse ; by Witu1am Hueerns, D.C.L., LL.D, FBS. © 
[In the number of this Journal for last February is a state- 
ment, by Dr. Huggins, of his method of photographing the 
corona of the sun without an eclipse. The following account, 
of his more recently devised methods, and of the results ob- 
tained, was communicated to the British Association at South- 
port, and is furnished by him in proof from the British Journal 
4 
of Photography for this Journal. ] 
Tam indebted to Miss Lassell for the loan of a seven-foot 
Newtonian telescope made by the late Mr. Lassell. The spec- 
ulum, which is seven and a-quarter inches in diameter, pos- 
sesses great perfection of figure, and still retains its original 
fine polish. I decided not to use more than three and a-half 
inches of the central portion of the speculum—partly for the 
reason that a larger amount of light would be difficult of man- 
agement, and partly because this restriction of the aperture 
would enable me to adopt the arrangement which is shown in 
the diagram. 
Tt will be seen at once from an inspection of the diagram 
that in this arrangement the disadvantage of a second reflection 
by the small mirror is avoided, as is also the mechanical in- 
Convenience of tilting the speculum within the tube, as in the 
ordinary form of the Herschelian telescope. The speculum 4 
remains in its place at the end of the tube aa. The sm ] 
plane speculum and the arm earrying it were removed. The 
Open end of the tube is fitted with a mahogany cover. In 
this cover at one side is a circular hole /, three and a-quarter 
Inches in diameter, for the light to enter; below is a similar 
hole, over which is fitted a framework to receive the “backs” 
Containing the photographie plates, and also a frame with 
fine ground glass for putting the apparatus into position. Imme- 
diately below, towards the speculum, is fixed a shutter with an 
across more or less rapidly by the use of india-rubber bands 0! 
different degrees of eae f In front of the opening /is fixed — 
a tube c, six feet long, fitted with diaphragms, to restrict as far 
