The herald., 1896-08-11
PHENOMENA OF ECLIPSE
How They Are Observed-Some OF the New
Instruments Used

How They Are Observed-Some OF the New
| Instruments Used
There was a total eclipse of the sun
Sunday, but it was only visible on the
other side of the world. The event has
attracted much interest among astrono-
mers, and it is expected that the re-
| suits of the observations will prove of
| great value to science.
The moon, as it revolves around the
earth, gets almost exactly between the
latter and the sun every twenty-nlne
| and one-half days, but it is usually just
trifle too high or too low to pass di-
rectly in front of the sun. But yester-
! day the three bodies were in a direct
line, and consequently the moon COM
pletely concealed the sun from por-
| ton of the earth's inhabitants for
| very brief period of time The event was
visible, however, only on the other side
of the globe from US
Shadows are larger than the object
which casts them if the source of light be
! smaller, says the New York Tribune;
| but the moons shadow Will be much
smaller than the moon itself, because
the Illuminating body (the SUM is vast
ly larger than the obscuring body. The
| diameter of the one is about $780, ,000 miles,
and that of the other about 1000. The
| patch of darkness falling on the earth's
| surface therefore, was not more than
| 200 miles across, and this went rushing
| along at rate estimated at between one
| and two miles a second.
So skillful are astronomical mathema-
| ticians that they are able to compute the
| precise path which the moving shadow
will take Unless the observer is placed
| within the prescribed limits. of course,
he will either see the eclipse as partial
| one or not at all. The belt OF totallty
! begins over the ocean away up north OIL
| Great Britain, sweeps eastward across
| Northern Norway and the island of Nova
| Zembla, then curves down slantwlse
| across Siberia to Yezo, one of the north
| ern islands of Japan, and out into the
| Pacific ocean.
More than a dozen parties of profess
| sional scientists and countless amateurs
| had placed themselves along the route
| with the hope of witnessing, Sketching
! and photographing the phenomenon.
| Several popular excursions by steamer
| went to Bodo, town on the west coast
| of Norway, up in latitude 6I12. Most OF
| the Bitish astronomers We're encamped
| on the shores of Varanger Ford, noun
| tain-gi bay, piercing the coast little
| east of North cape, and reaching west
ward This is in latitude 40, where Tor
| a part of the summer, the sun never sets,
| but simply goes round and round dlp-
| ping closer to the northern horizon
| than to the southern. Russians had posts
of observation In Nova Zembla, at the
| mouth of the river Obi, and also on the
Lena and Amoor rivers. At least four
| parties-two from America. one from
England and one from France-conduct-
| ed operations in Yezo.
| The principal work done was pho
| tographic in character A sharp watcn
! was kept for faint hints of the CO.
roma both before and after totality, and
| at these times, as we'll as during COM
| plete observation, many amateurs
made rough sketches of the outline and
| proportions of what they saw. But such
| drawings, even when made by trained
| astronomers, often disagree enough to
| be untrustworthy. In 1893, to be sure,
| four great streamers We're distinctly
seen reaching out from the moons
| edge, which did not appear in any pho
| tograph. Nevertheless, the chief reli-
| ance is placed on the record made by the
sun itself with the aid of a regular cam
| era or telescope converted into one.
| These Instruments vary in aperture.
| focal length and other features, but
| have common purpose
| Among the new instruments used on
| this occasion was a glycerine clock, made
lDT lHc AiIliltrSt cOllcSe eEpeulllbu III
| Japan. Its mission is to regulate the
| movements of a big platform so that
| twenty or twenty-five cameras, tele-
| scopes, spectroscopes and polariscopes
! mounted on the latter will all gradually
| change their aim as the sun crosses the
| sky. Prof. Todd also used an entirely
| automatic electrical mechanism which
| alternately exposes and changes the
| Photographic plates with great rapid
| ity. Prof Schaeberle of the Lick obser-
| vatory, also in Yezo, took along Il
now famous telescope. with which he
| gets wonderfully large and delicate pho
J tographs. The arrangements of his an ..
paratus was changed so that his plato
holder. instead of the lens, shifts its
| position as the sun moves Mr.. Burcll-
natter, an Oakland (Ca1) astronomer
| who accompanied the Lick party, tried
| for the first time an appliance de-
! signed to Offset the intensity of the inner
part or the corona. so that details We're
| as distinctly shown in that region as
| turther cut. Some observers and ph1 :.
| toeraphers. instead of changing the di-
| rection in which their instruments point.
| Kept them stationary. but reflected
, the suns image into them by means
of mirrors which are suitably moved by
clockwork. Mirrors have been used in
| very nearly the same way before. When
| one reflects star it is called a ''sidero-
| stat when it is used in solar work it IS
| called "heliostat." But hitherto the
machinery has only rocked the mirror in
| one particular way. 1t has been found,
! however, that in order to correct the
tendency of the image to revolve on the
| mirror itself, another motion is also re ..
| quisite. A device provided with clock
| work which performs both these
functions is called "coelostat" This
Is French invetion. perfected by NJ
Lippmann. and was tried by several
| of the European observers this year for
| the first time.
According to astrologers, this eclipse
is likely to be followed by disasters in
the Orient, owing to the fact that it oc-
ours in the conjunction of the evil plan
ct Mars, Herschel and Saturn, and Of