"I was most fortunate in having
. . . permission to establish my station on the ruin of the celebrated old
castle..." |
"...a volcano about 25 miles away,
and which had sprung into unwonted activity during the past night, belching
forth for hours enormous volumes of smoke and steam." |
|
Excerpts from
American Eclipse Expedition to Japan:
The Total Solar Eclipse of 1887
"Preliminary Report of Prof. David
P. Todd, Astronomer in Charge of the Expedition."
Published by the Observatory
Amherst, Mass., 1888
I left Boston the 9th June for Japan, going
by way of Montreal and the Canadian Pacific Railway to Vancouver, the coast
terminus, and thence embarking for Yokohama in the steamship 'Abyssinia.'
Yokohama was reached the 8th July, and steps
were at once taken toward locating the instruments in the most advantageous
spot. I was most fortunate in having . . . permission to establish my station
on the ruin of the celebrated old castle occupied by the Abe family until
the revolution of 1868.
Our main instrument was a horizontal photoheliograph
of nearly forty feet focal length. Two weeks' time was quite sufficient
for the substantial completion of this instrument, in so far as the parts
required for photographing the partial phases of the eclipse were concerned.
Of these we had planned to secure 100 pictures; but I had determined also
to attempt coronal photography with the same apparatus, hoping to obtain
eight or ten negatives of the corona of such size that subsequent enlargement
would be undesirable.
Special modifications of the exposing-shutters
and the plate-holders had to be made, and a light-proof tube or camera the
whole length of the telescope had to be constructed, before the complete
drill for the eclipse could begin, and this required a week or ten days
more. As was anticipated, too, we found on photographing artificial 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 the position
angles. Mr. Hitchcock, whom I had appointed photographer of the Expedition,
undertook a variety of experiments to overcome this difficulty, and with
entire success.
To assist in the operations of the photographic
house, we were fortunate in securing the services of Mr. K. Ogawa of Tokio
[sic], a Japanese photographer of wide experience, and Dr. Y. May King of
Amoy, also a highly skilled manipulator. For some minutes immediately before
the beginning and after the end of totality, the partial phase exposures
were to be made every 15 seconds; while the large plates for the corona,
with exposures varying from 1 second to 15 seconds were to be handled as
rapidly as possible. We found that there was a loss of about 5 seconds between
the plates--or something like one-sixth the entire duration of totality.
With so efficient a photographic corps, and the drill which we all underwent,
I had the best of reasons for anticipating complete success.
I had long had the idea that, by means of a
system of light rods, or of cords and pulleys, led from the heliostat into
the photographic house, the chief astronomer making the exposures might
have the reflecting mirror under his immediate and constant control, and
thus dispense with the customary assistant at the heliostat pier for adjusting
the mirror in right ascension and declination. All the devices for this
rather complex system were practically executed by Mr. Pemberton, and sufficed
to give me perfect command of the mirror from the dark room.
I had an occulting-disk mounted on a rod attached
firmly to the gable of the photographic house, so that its shadow as cast
by the eclipsed sun would fall about fifty feet away, in the area enclosed
by the upper castle wall. Here I stationed Mrs. Todd, assisted by Professor
Kikuchi, of the Imperial University, and provided with all the paraphernalia
for seeing and sketching in their correct relations the faint, outlying
streamers of the corona. On the north-west corner of the castle I stationed
Mr. K. Acino, a student of astronomy in the University, and interpreter
to the expedition . . . he was 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 forenoon gave us a perfect sky, with no
indication whatever of approaching 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 Nasu-take, a volcano about 25 miles away, and which had sprung into unwonted
activity during the past night, belching forth for hours enormous volumes
of smoke and steam. The dense clouds . . . lay over the sun until the eclipse
was past . . . . In general, the whole of the main island was obscured on
the eventful afternoon. |