New-York tribune., 1875-03-08

atmospbere and the Clouds a. well a. the uncer-
tainty of observers noting the same phenomenon at
the exact instant of contact all come IN to render IL
difficult il not inadvisable to compare contacts de-
duced from photographs with contacts observed d.
recty 1t is true that in India the English work was
eminently successful and that 100 photographs were
taken; that in Egypt at Cairo. Suez and Theses
the parties obtained everything they sought pus
these observations are comparatively yalueiess
the observations at the other end of the base hne
az, for instance. at New-Zeaand-have 1alied'
Looking over the whole ground, it would seem that'
so far as can new be judged the English, at Des''
have imperfect data on which to found their calcu-
tons by the Delisiean method for the determiha-
tion of the solar paralax and that the Americans
relying on the Halleyan method aud photography
are more fortunate.
By combination or modification of methods the
English will doubtless be able somewhat TO utiiSe
their successful observations at Rodriguez, and the
fairly good fortune of Lord Lindsays party on
Mafritius Island Mr. Proctor urged the suggestion
that the Cape of Good Hope be occupied. Photo-
graphs taken there can be compared with those
taken in India. 1t Is said that IA photographs were
made at Cape Town, but as the same correspondent
adds that they show the black DROP they may
not be of value for II is generally conceded that the
formidable black drop" of the older translts was
caused by the imperfectOls OF the telescopes then
in use.
WORK ACCOMPLISHED BY OTHER NATIONS
The reports from stations of other than the Englsh
and American are yet too meaeer to supply conciu-
sons as to their value. The Germans had exceieht
success ON the Auckland Islands, and the reports
from their other stations indicate that their total
results may possibly be equal in value by themselves
to those which the English have obtained. Some OF
nj audt heir
vations at Pekng regarded in several respects
fully on a par with those of the Americans there;
but their party at the Campbell Island was wholly
unfortunate in respect to weather that locality
proving more unfavOrable than any other OF the
southern stations There has been a general ex-
preston of sympathy among astronomers
for the unlucky party at Campbell lsianu,
as the observations there if successful would
have been exceedingly valuable. The Rus
slams deserve great praise for their efforts wnrch
were indeed noteworthy They established long
line of stations in northern ATTITUDES extending at
least from Teheran in Persia to the shores OF the
Pacific. These stations were well-appointed ana
well selected and in Siberia were numerous. Should
the Russians wish to calculate from their own data
they have pretty long east and west line between
for instance the Persian stations where tney were
successful and HakodadI in Japan where they had
long line during the Winter and in high lattudes,
there were, of course many failures. But some
results were obtained that should prove of the high
est value when astronomers come to international
comparisons, because these stations were so far to
the north Nertchnsk where the observations are
reported as entirely successful the highest north
ern station included in the expectations of asrono-
mers its data, compared with southern stations,
will give the greatest possible difference OF time;
that u.s. the most extended basis for calculation.
The Italians have made speciality OF spectre
scopic observations. The exact yalse of this class
of work in computing the solar paral TX Is even
more an open problem than the Photographic
method. In the present state of knowledge II may
well be doubted whether any comparison can be
made between spectrOscOpc and visual or photo
graphic data Thus the Italian party under Tacchini
at Bengal where they successful both with
spectroscopic and ordinary eye observations, found
the last external contact by the former two minutes
earlier than ~ the latter method indicating that
the apparent diameter of the sun, viewed with the
spectrOscOpe is smaller than that which is apparent
to the eve. Several other nations have taken a
minor part in observing the transit, and it may here
be mentioned that tne Dutch party at Chefoo and
the Mexican observers at Yokohama both had good
success.
The following table shows the time differences be-
tween several Of the stations referred to- OF course
the greater the time difference the greater Is the
basis for comparison by which the paralax can be
computed. These figures are taken from an essay
written by Mr.. Proctor, when he was urging the
superior claims of the Halleyan over the Delislean
method and the actual figures for Delisean stations
are modified, with reference to comparative proba-
bi;ies of error in observing to bring them on
equal footing with Haleyan stations.
TABLE OF TINE DIFFERENCES BETWEEN STATIONS
Ees-Zes- Ne Adelaide
AID bourne and
,iaf1i tTard H.hs and EDfr