Year: 1875

for measuring the cusps and the progress OF tne
1t has o clock-work supplied with Bonds spring gov
erpor which was found 10 work admirably IN AoePus
the instrument pointed the object even WIN .no
highest powers Tho house for the equa'oriai nsu


rakine roof and slit, which was adapted canvas
IN exclude the suns rays and wind except ata
small opening for the telescope. This telescope was the
work OF Alvan Clark Sons, and considering its sze'
accomplished all that could be expected IL WILL now
ever, be matter OF regret that the teie-
scopes for these expeditions could not have been OF


larger size 30 that they might have been pushed TO


hi CHER power than these would permit. (2) transit
instrument by stackpols OF NewYork. 1t s OF form
now being revived which the eyepiece Is In the AXIS
and the observer not change his position IL mas


reflector at the angle which directs the rays into the
eyepiece. The form has many conveniences ana ue'
serves to be improved and perfected This particular In
srumept was found work well. An inequality or the
pivot greater is convenient, was the only notice
able defect 81 A clock by Howard adapted to cleo
trcal registration. a. Two breakcircut chronometers
by Negus Of New-York These were found to work ad-
mirably. One Of them was almost absolutely With
out rate From the convenience OF moving them into
different rooms where they were needed, the cnro-
nometers we're found much useful than the clock


5) transit instrument by Wirdeman made after the
plan devised by Prof Davidson. This instrument be-
longed TO the Coast Survey and brought out as an
extra instrument to be used for longitude work
o. Two chronographs for recording time, the one an
American instrument recording on cylinder; the
other German instrument, recording on fllet From
the groans which the writer often heard over the reading
of the observations registered the lets, he infers
that this style Is not in favor among astron-
omerS. G) Photographic Instruments These con-
sisted OF telescope OF about 40 feet focal
distance placed horizontally in the meridian II dnered
however from an ordinary telescope in having no tube
connecting the object glass and the focal point The
object glass was mounted heavy iron plate sup
ported by sheet iron column. Behind 1t was placed
glass mirror reflect the image Of the through the
object glass This mirror was mounted on an axis
turned by clock work. intended to follow the sun auto
matcaly. For some reason the performances OF this
heostat never very satisfactory and except Tor
short time at the middle Of the DAY the services OF


man were constantly needed to adjust by hand the
image Of the The focus of the object glass was
located within the Photographic house. Here
was set glass diaphragm on whlch
| were marked horizontal and perpendicular lines
plumb line OF 1ne silver wire also hung behind TINS
plate In every photograph Of the sun tue cross neS
OF the diaphragm and the plumb line were also taXep'
and the subsequent measurements they VIII serve 10
determine the exact position OF the image at tne instant
| Of the photograph. screen covered the opening
toward the object glass; which could either be moved
by hand or by q spring. 1t had slit adjustable in
width 70 the time required for exposure 1t was also


ngenously arranged to break circuit and thus record
itself upon the cnronograph at the instant that the slit





equipped with full supply Of plates and chemicals and
apparatus all parts OF their work In preparing


for the great day the photographers were most assidu
Mr. seibeTt scarcely left the hill day or nlSht ana
for days before the transit Prof Davidson had es
tablished mess tent and cuisine upon the ground to
save the party the time required in going and coming
PREPARING FOR THE TRANSIT.


The amount Of preparation required for such an
event can scarcely conceived The instruments must
be up and protected by houses The most delicate
tests and adjustments must be made in every part Jhe
astronomers must determine their latitude and longi-
tude. They must determine the error and rate OF all


their clocks and chronometers. They must see that
their batteries and cbronographs in working order
They the value of the mcrometers and
again and again the practical working Of every peoe OF
apparatus. The exact distance from the Photographic
object 10 the position OF the Photographic plate
must be repeatedly and most carefully measured with
the most delicate appliances. The exact moment of
each phase of the transit must be computed for the par
ticular station well the precise points of ngress
and egress. All these Measurements and compu-
tations must be recorded in detail for trans
mission TO Washington; and still more, must
be duplicated to avoid the chance of loss in transmits
sion. The photographers were equally busy In their
preparations. After their apparatus was set up they
practiced daily the details Of their operations and
studied the effects OF changing states OF atmosphere
They took photographs Of the views in the vicinity.
They resolved themselves into machinists and con-
structed with their own hands what additions their ap
paratus required They turned mechanics and built
sheds and shelves and ladders and benches and boxes
The practical genius and training of
his two assistants IN the Boston School Of Technology
had ample opportunity for their display They con
structed an improved sde by which photographs could
be taken at the rate of three more per second


The weather during the two months preceding the
transit was variable For ten days after the ARRIVAL Of
tho party it perfect. Then followed clouds and
RAIN AS the time drew the bright days which
everybody had predicted for December did not
UnavainG anxiety sat upon the face OF the chief and
his subordinates They had done everything which
science experience had suggested. and now they
awaited the result few weeks after the arrival OF
the American party at Nagssak French party under
the charge OF the iustrious Jansen, came upon the
ground His plan had been TO locate Kobe on the
Inland sea But after examining the place he concluded
to come Nagasa. 1t seemed pity that two parties
should Thus be exposed TO exactly the chances
Of bad weather The general interests OF science would
certainly have been better consulted II two parties
had in the place Besides, NJ Jansen did not
propose to the teegrapbic cable for determining
longitude and hence moro inland point might have
been selected. The French camp pitched upon a
hill north Of the town. about three miles distant from
the Americans The two exactly faced each other, and
we could look with glass and see them watching
They worked nimbly and vigorously as became
men who had time TO lose Courtesies were
changed between the Chiefs and mutual assistance was
rendered The French outfit elaborate than
the American. They had nine-feet and eghtfeet
equatorial to OF which Prof. Jansens specrOscope
was attached. Besides these they had very complete
Photographic arrangement For this purpose they used
O telescope Of about IL feet focal length, with
rsngement By which the focal image again
enlarged TO about four inches diameter and re-
received upon sensitive plates Part OF the photo
graphs be upon glass; and part by the daeuer
reotype process upon silver Prof Jansen had devised


apparatus for revolving the sensitive plate aud thus