6io 



NA TURE 



[^Od. 27, 1887 



president, Mr. Narabara, our Expedition is deeply in- 

 debted, we pass through Utsunomiya at the distance of 

 65 miles, and at 113 miles reach Shirakawa, a town of 

 about 10,000 inhabitants, and situate 10 or 12 miles north 

 of the centre of the shadow-path. Here I found a spot 

 forming, in many respects, an ideal location for an eclipse- 

 station. Within a quarter of a mile of the telegraph- 

 office and railway-station, and in an unfrequented part of 

 the town, was the ruin of the celebrated old castle erected 

 some 300 years ago, and occupied by the Abe family 

 until the revolution of 1868. Permission to establish my 

 station on the castle walls was given by Count Oyama, 

 the Minister of State for the Army, under whose control 

 this and similar castles elsewhere in Japan, formerly 

 possessed by the Daimios, now are. The massive walls 

 rise to a height of about 80 feet above the surrounding 

 plain, and afford a capital foundation for the instrumental 

 equipment — not to say the seclusion so desirable in the 

 mounting and adjustment of delicate apparatus. Of the 

 mountain-range 25 or 30 miles to tiie'west and north- 

 west, and its cloud-creating propensity, we had apparently 

 little need for fear — in fact, a month's residence in the 



castle gave us a large proportion of afternoons on which 

 an entirely satisfactory record of the eclipse in all its 

 stages could have been secured. 



Our main instrument was a horizontal photoheliograph of 

 nearly 40 feet focal length, with which we hoped to expose 

 100 plates during the partial phases of the eclipse ; but I 

 had determined also to attempt coronal photography 

 with the same instrument, hoping to obtain eight or ten 

 negatives of the corona of such size that subsequent 

 enlargement would be undesirable. At the focus of this 

 telescope the sun's image has a diameter of 4^ inches, 

 and dry plates 17 X 20 inches had been provided for this 

 work. Also an extra mirror, finely silvered by Bra shear, 

 was taken along for the heliostat, to replace the un- 

 silvered mirror ordinarily employed, shortly before totality 

 came on. After the special modifications of the ex- 

 posing-shutters and plate-holders had been made, and a 

 light-proof tube or camera the whole length of the tele- 

 scope had been constructed, periodic drill for the work of 

 eclipse-day was at once begun. For some minutes imme- 

 diately before the beginning and after the end of totality, 

 the partial phase exposures were to be made every fifteen 



seconds, while the large plates for the corona, with 

 exposures varying from one second to sixty-four seconds, 

 were to be handled as rapidly as possible : we found that 

 there was a loss of about five seconds between the plates, 

 or something like one-sixth the entire duration of totality. 

 With a very efficient photographic corps, and the drill 

 which we all underwent, I had the best of reasons for 

 anticipating complete success. 



As was foreseen, too, we found in photographing arti- 

 ficial crescents — very slender ones — that no image of the 

 plumb-line appeared on the plate ; there was thus no 

 initial line of reference for the measurement of position- 

 angles. Mr. Hitchcock, whom I appointed photographer 

 of the Expedition, undertook a variety of experiments to 

 overcome this difficulty, and with entire success ; the 

 form of apparatus finally adopted will be detailed in the 

 report of the Expedition. To assist in the operations of 

 the photographic house, we were fortunate in securing 

 the services of Mr. Ogawa, of Tokio, a Japanese photo- 

 grapher of wide experience, and Dr. Y. May King, of 

 Amoy, also a highly-skilled manipulator. 



As wet plates appeared to me preferable in many ways 



to dry ones for the partial phases, Mr. Hitchcock and 

 Mr. Ogawa instituted a thorough series of experiments in 

 the preservation of sensitized films, at first with glycerine, 

 and subsequently more successfully with sugar. The 

 results of this work made the wet plate, with its fine- 

 grained film, as available for rapid manipulation in the 

 photography of celestial phenomena as the dry plate has 

 hitherto been found to be. It was shown that the plates 

 might with entire safety be removed from the sensitizing 

 bath from two to four hours before exposure and develop- 

 ment, if treated with the sugar preservatives, and proper 

 precaution was taken to keep the films from drying. The 

 details of this process will be embodied in the report of 

 the Expedition. As an extreme test we exposed, on the 

 day after the eclipse, a box of the plates which had been 

 sensitized and preserved for eclipse-work some twenty-six 

 hours previously, and found that they gave sun-pictures 

 photographically perfect. 



In compliance with orders issued by the Secretary of 

 the Navy, two officers from the Asiatic squadron, Lieut. 

 Southerland and Chief-Engineer Pemberton, of the 

 U.S.S. Monocacy, reported to me for eclipse-duty on 





