Page:Proceedings of the Royal Society of London Vol 69.djvu/266

250 aperture and 32 inches focal length. These two instruments were placed horizontally, the camera of the R.R. lens being placed imme- diately above the photoheliograph tube, and both were supplied with light by means of a 16-inch mirror mounted on a coelostat. The second division consisted of the Greenwich coronagraph, and Mr. Ever- shed's prismatic camera. The coronagraph was mounted in a hori- zontal position, and the prismatic camera was fixed immediately above it, both instruments being supplied with light by a 12-inch mirror mounted on a coelostat. Between the two a clock was mounted which rang an electric bell close to the camera end of the photoheliograph, and another close to the 12-inch coelostat, at every tenth second during totality. The instruments were fixed upon boxes filled with stones, and to shelter them skeleton huts were formed, each consisting of three pairs of poles carrying a ridge-pole. Tarpaulins were then thrown over the ridge-pole, and pegged down to the ground. When any instrument needed to be used, one or more of the tarpaulins could be thrown up on the side upon which it was desired to observe. During the eclipse all the tarpaulins were entirely removed, except one fixed round the 10-second clock, which was left in order to shelter the pendulum from the wind.

The positions of the instruments relative to the Observatory buildings are shown in the accompanying plan, in which are also indicated the positions of Mrs. Maunder's instruments, which were also set up in the Observatory grounds.

The above arrangement of the instruments was finally completed by May 11 when the prismatic camera was mounted, one week before the eclipse.

Personnel. The following list gives the names of those who took part in the observations:

With the 16-inch coelostat and its telescopes

T. F. Claxton Mauritius photoheliograph. Large-scale photo- graphs of inner corona.

Bombardier A. J. Cox Recorder to Mr. Claxton.

Bombardier C. A. Truman Carried plate-holders for Mr. Claxton to and from dark-room during the partial phase.

Charles G. Garrioch Changed the plates in the plate-holders during the partial phase.

T. A. Pope Rapid rectilinear lens. Small-scale photographs to show extension.

E. G. Rowden Exposed at the object-glasses of both the photo- heliograph and the R.R. lens for Mr. Claxton and Mr. Pope.

With the 12-inch coelostat and its telescopes :

E. Walter Maunder Greenwich coronagraph. Large scale photographs of corona.