Page:Proceedings of the Royal Society of London Vol 69.djvu/238

222 I was observing the diminishing crescent through the guiding eye- piece of the spectroscope when Dr. Wallace called out " Stand by," and at once hastened to the plate-holder to make exposures for the " flash." Five exposures had been made, each twice as long as I had intended to make had there been no cloud, and as the counting went on longer than I anticipated I decided to make one more exposure, thus using a sixth plate at the beginning of totality. Immediately after having moved Plate No. 7 into its place with shutter closed, I returned to the guiding eye-piece to set the corona ring between the slits. I could see one side of the faint ring distinctly, but could not see the slits, but having learnt by experiment in the course of the morning what movements of the declination and R.A. slow-motions were required to move the image from one position to the other, I made those movements and, being still unable to see the slits, looked up at the corona. There was no difficulty in seeing the dark moon, so to speak, but the corona was quite indistinct beneath the cloud, and was surrounded by a colourless bright ring, which is referred to in the " General Remarks." My notes, written directly after the eclipse, con- tain the following :

" I heard count ' Thirty,' and took a candle lamp [which was standing in the tent] to try to illuminate the slit-plate, but failed to get light in. Then, as ' Thirty-five ' was called, I turned to polariscope. No trace of polarisation. Turned to second polariscope and could see no trace of polarisation, but saw mackerel sky very strong as it seemed, all over region near the sun, especially to N.E. . . . Return- ing to 4-prism spectroscope I found the whole ring of the corona visible, but still could not see the slits. Tried candle again ; no use. ' Two minutes gone ' was called. Ring was clearly lighter, but slit not visible ; cloud pretty strong over corona, which could only be traced about half a diameter from the limb. I walked towards double tube and met W. [coming back into hut], who was I thought waiting for improvement in cloud. He asked, ' Is Savart set.' ... [I replied 'Yes' and] he at once exposed plate-holder No. 2 in the double camera, and I heard ' 2 m 35 s ' called as I walked back to spectroscope. Corona was brighter, and I found slits visible, and moved corona ring on to the right place and exposed at 2 m 45 s [having lost two minutes and fifteen seconds, exactly half the intended exposure]. Then I turned to polariscope and still failed to see any bands, and then went to visual grating. . . Clouds seemed thinner when I looked up at sky, arid Mercury and Venus were very bright. I had one more look at corona on the slits of 4-prism [and found it still correctly adjusted on the slits, and the clockwork evidently driving well], and then as Briggs came back into hut, I looked at polariscope for third time and again failed to see any bands on sky. At 5 m s I saw B. and Mrs. N. close their exposures, and I closed mine at 5 m 3 s, the rubber band of