Page:Proceedings of the Royal Society of London Vol 69.djvu/232

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Throughout the preparations for the observations I received most valuable assistance from my friend Dr. L. Wallace, who travelled from Burma to Sumatra especially to help in the work of the expedition. Arriving at Sawah Loento on April 18, he accompanied us to Ayer Karoe, and assisted in every possible way to further the aims of the expedition from the moment of his arrival until all the instruments were packed up again on May 26 after the eclipse. It is a great pleasure to acknowledge my deep indebtedness to him for his friendly and efficient help.

A few days before the eclipse, Lieutenant-Commander Oldham, of H.M.S. " Pigmy," was good enough to tell off Lieutenant H. D. Briggs to come up to Ayer Karoe, together with two petty officers from the " Pigmy," to help in the final preparations, and in the observations. They took part in the preparatory drills and rehearsals, and gave most efficient assistance.

In the observations during the eclipse itself

Dr. Wallace was in charge of the double tube camera, and gave the signals, watching the diminishing crescent of the sun upon the blue focussing plate of the Dallmeyer telephotographic camera.

Lieutenant H. D. Briggs exposed the plates for the objective-grating camera, after having assisted me in making the final adjustment with the diminishing crescent.

Mrs. Newall made exposures with the quartz spectrograph.

I made exposures with the 4-prism spectrograph, made observations for detecting the polarisation of the atmosphere, and observed the green coronal ring with the visual objective-grating spectroscope.

E. Hobart, Chief Stoker, and H. Taylor, Petty Officer, H.M.S. " Pigmy," counted seconds aloud from a metronome, and handed plateholders.

At 30 seconds before totality Dr. Wallace, watching the diminishing crescent of the sun, and gauging its length by a marked template which I supplied him with, gave a signal to Lieutenant Briggs, and at 15 seconds he called out " Stand by." Hobart began counting seconds with the metronome, until Dr. Wallace gave the signal " Go," when the disappearance of the crescent showed that totality had begun. Then Hobart ceased counting, and Taylor began afresh, and counted steadily on to the end of the third minute ; in this count he began each minute with " one," " two," " three," and Hobart called " One minute gone," " Two minutes gone," at each new minute. Then Hobart resumed the counting of seconds, Taylor calling the minutes up to the completion of the sixth minute, it being expected that totality would last for 5 m 42 s, if the prediction based on the ' Nautical Almanac ' elements were true, or for 5 m 32 s if the prediction based on a recent