Oct. 27, 1887] 



NA TURE 



611 



m 



my arrival in Yokohama, and their services were zealously 

 and most effectively rendered. In addition to his work 

 as executive officer, I placed Lieut. Southerland in 

 charge of the 9 foot coronagraph, sent out by the Picker- 

 ings from the Harvard College Observatory. The 

 objective of thi's instrument was the 7j-inch Clark glass of 

 he equatorial of my own Observatory at Amherst, while 

 he dry plates, with the instructions for their manipula- 

 1 on, were identical with those furnished by the Picker- 

 ngs to Prof. Young, who carried to his Russian station a 

 )|-inch Merz glass, also lent from the larger transit- 

 mstrument of Amherst College Observatory. I have not 

 yet been able to learn whether Prof. Young was favoured 

 with a clear sky during totality ; but, if he was, it is the 

 more regrettable that clouds covered the sun at Shirakawa, 

 as the first serious attempt to obtain trustworthy evidence 

 if rapid changes in the corona has thereby come to nought. 

 It will be many a year before another eclipse occurs with 

 two stations geographically so well placed for this special 

 research as were Russia and Japan. Prof. Pickering 

 desired me, if practicable, to place all or a portion of the 

 •corona-apparatus provided by this Observatory on the 

 summit of one of the mountain-peaks of which there are 

 several adjacent to the centre of the shadow-path, notably 

 ~ antaisan, 8500 feet high. Dr. Holland made the ascent 

 this mountain about the middle of July ; but his report 

 of its difficulties, together with the highly probable cloudy 

 condition of the summit during the eclipse, led me to 

 abandon farther consideration of this mountain ; while the 

 other peaks were too far removed from Shirakawa to 

 permit of occupation with the time and assistance at my 

 disposal. The remainder of Prof. Pickering's apparatus 

 was therefore mounted alongside the photoheliograph at 

 the central station ; the double coronagraph, two 5-inch 

 lenses of about 3 feet focus, being operated by Dr. Ames, 

 ;'.S. Navy, while Dr. D. B. McCartee attended to the 

 xposures with the 4-inch short-focus camera, and Mr. 

 J. R. Greathouse to the exposures of plate-holders for 

 letermining the actinic effect of the coronal light. 



The valued service of Mr. Pemberton is worthy of 

 special mention here in rendering the photoheliograph less 

 mwieldy for rapid work than I had found it formerly. By 

 neans of an ingeniously-devised system of cords and 

 )ulleys, led from the heliostat into the photographic 

 louse, the reflecting mirror was placed under the 

 nimediate and constant control of the chief astronomer 

 naking the exposures : it was thus possible to dispense 

 \ith the customary assistant at the heliostat pier for 

 idjusting the mirror in right ascension and declination. 

 A very simple device made it possible to see the bright 

 reflected image of the sun while at my post in the dark 

 room, and adjust it accurately on the plate without opening 

 he exposing-slide. 



The importance of Newcomb's and Langley's observa- 

 ions of the outer corona in 1878, and attempted by 

 '.ockyer in i836, had not escaped me, and I had an 

 'cculting-disk mounted on a rod attached firmly to the 

 -;able of the photographic house, so that its shadow as 

 cast by the eclipsed sun would fall about 50 feet away, in 

 the area inclosed by the upper castle wall. Here I sta- 

 tioned Mrs. Todd, provided with all the paraphernalia for 

 seeing and sketching in their correct relations the faint 

 outlying streamers of the corona. 



Of two 3|-inch telescopes lent by Admiral Yanagi, 

 Hydrographer of the Imperial Japanese Navy, one was 

 reserved for the optical observation of first and fourth 

 contacts, and the search for intra- Mercurial planets ; while 

 the other was committed to Dr. Holland, a skilled artist, 

 with instructions to sketch as far as possible all the 

 details of the corona adjacent to the solar poles. 



Mr. Nakagawa, the Director of the Naval Observatorj', 

 with his assistant, made a thorough series of meteoro- 

 logical observations throughout the eclipse period, follow- 

 ing the system elaborated by Von Bezold and recommended 



by the German Meteorological Conferencefor the observers 

 in Russia. On the north-west corner of the castle wall I 

 stationed Mr. K. Agino, a student of astronomy in the 

 University, to make detailed and precise observations of 

 the diffraction bands, and to observe if possible the sweep 

 of the lunar shadow across the extensive rice-fields 

 below. 



The purely eclipse results of the work at Shirakawa 

 were disheartening in the extreme. The forenoon gave 

 us a perfect sky, with no indication whatever of approach- 

 ing cloud : all were confident of entire success. But 

 about an hour before the time of first contact, a slender 

 finger of cloud began to rise from the west, coming at 

 first directly above the summit of Nasutake, a volcano 

 about 25 miles away, and which had sprung into un- 

 wonted activity during the past night, belching forth for 

 hours enormous volumes of smoke and steam. The sun 

 was entirely invisible during the first half-hour of the 

 eclipse, when a brief interval of partly clear sky gave 

 time for adjusting the heliostat and making ten or twelve 

 exposures. The sun being very faint, only five of these 

 photographs are available for measurement ; and these 

 were the only pictures that could be taken with the photo- 

 heliograph. The dense clouds, leaving a large clear 

 area most of the time about the zenith, lay over the sun 

 until the eclipse was past, save only a moment shortly 

 after totality, when there was a partial clearing, but too 

 brief, and the sun too faint, to allow of the necessary 

 adjustment of the reflecting mirror. 



As totality drew near, it suddenly occurred to me that 

 a good observation of second contact might be possible 

 by watching for the approach of the moon's shadow 

 among the clouds ; but my attempt to do this failed, the 

 light appearing to me too much diffused to permit of any- 

 thing better than a rough approximation to the time of 

 contact. I found subsequently among Mrs. Todd's notes 

 of the eclipse that totality appeared to her to come on, 

 not evenly, but as if by jerks— a phenomenon which may, 

 I think, have been due to the extinction of the sun's light 

 from one cloud after another, as the lunar shadow ad- 

 vanced over the north-western sky. The weather-map 

 for August 19, which came to our station from To'do the 

 day after the eclipse, gave us some idea of the odds we 

 had been labouring against : the sheet for 2 p.m. showed 

 clouds at all stations of the Meteorological Service ex- 

 cept one, and that far removed from the belt of totality. 

 In general, the whole of the main island was obscured on 

 the eventful afternoon, and a view of the eclipse was per- 

 mitted onlv to those so fortunate as to be located in the 

 line of the' small apertures, here and there, through the 

 general cloud area. These were numerous enough to 

 enable voluntary observers, scattered over the central 

 portion of the belt of totality, and for whom I had pre- 

 pared instructions, to obtain a goodly number of drawings 

 of the corona. These instructions had been translated 

 into Japanese, and printed and distributed through the 

 co-operation of the Department of Education and the 

 Bureau of Geography of the Department of the Interior. 

 Altogether there are something like a hundred such draw- 

 ings ; but their value is uncertain until they are properly 

 collated. Much the best drawing which I saw was made 

 by Mr. Shuji Isawa, Chief of the Bureau of Compilation of 

 the Department of Education, who was fortunate enough 

 to be located in a spot in Western Japan, where totality 

 was seen in a nearly cloudless sky. He has kindly 

 furnished me with photographs of his drawing, one of 

 which is inclosed. 



Other Expeditions in Japan fared ill also— some of them 

 worse than my own. that sent out from the University 

 in charge of Prof. Terao, and located a few miles south of 

 Shirakawa, at Kuroiso, experienced not only heavy clouds, 

 but much rain during the eclipse, and no observations 

 could be made. At Sanjo, on the central line and south- 

 east of Niigata, Prof. Arai, Director of the Meteorological 



