New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1878-04-22
ACADEMY OF SCIENCES.
LAST DAY AND ADJOURNMENT.

MEASURES OF MISUNDERSTANDING THE NAMES
OF MOUNTAINS, STREAMS AND TOwSs-PRoFEs-
soR HRN;RY's PARTING WORDS AT THE CLOSE OF
THE MEETING.
JPRoN STAFF CORRESPONDENT OF THE TRIBUsE.I
WAsHrNGToN, April 19.-Again the mistake
was made OF keeping audience outside YEARLY walt
ing for than hour, while the members OF the
National Academy closeted in business meeting.
Warned by previous sad experience, the crowd DUNN
sed rapidly when the door did at the appointed
hour Notwithstanding its length the business meeting
accomp lished little except to provide for committee
to investigate and report Professor HewcOmbs plan
measuring the velocity Of light Most OF the time
was occupied in debating proposed changes In the constr
tuition When society engages in that sort of work 1t
very rarely does much else for long while The Amer
lean Association for the Advancement OF Sciences used
time in discussing its constitution at every
meeting till finally il reached crisis, remOdelled itself
under great excitement and since has gone ON con-
tentedly.
Taken as whole this has been one Of the most inter
estng meetings held by the Academy in recent years
though OF the essays of extraordinary merit
At one business sessions fOrtyave members
present and y0ted-a number which L believe Is
unprecedented. The attendance OF the public was
unusually large A Washington gentleman, to day, cx-
planned to the popular interest, as being chiefly due
to the discovery OF the Of Mars. That, he said
was the only thing of worldwide Importance dis
covered here notwithstanding the efforts Of Innumer
able investigating committees Hence the citizens feel
very proud Of IT. and to patrOnze science is now the
fashion in this city,
MEASURING STARLIGHT.
The first paper OF the morning by Professor E. C.
Pickering on Photometric Comparison OF the ComDo-
nents of Close Double Stars" 1t has become
generally recognized that systematic errors are
Of graver Importance in astronomy than accidental
errors In the done at Harvard Observatory
pains spared 20 eliminate errors OF the former KIND
Il easy observe with accuracy the difference in
brightness between the cOmponents Of double stars.
II an artificial star be used for determining the magni-
udcs It conuscs the observer by its unlkeness to real
stars To remedy this after the artificial star has been
compared with real one, the latter is used for new
comparison Il ls found that the eye does not, in the
beginning OF an evenings observations, attain its
highest constituencies After doing its best work, 1t
again loses power toward the end OF the observations
because OF fatigue want OF senstyeness Is one Of the
most serious sources OF visual error.
Professor Pickering mas devised an instrument for the
special purpose OF comparing the components of double
stars The images are separated by Ncolls prism,
and there are various contvlnces for preventing error
But even with this dOubestar phOtomcter, many pre-
cautions must be taken TO get the best results ana care
especially needed respecting the personal pccularities
~ the observer chart Is In preparation at Harvard
Of all the double north Of 400 latitude; at present
this work ia about half done, 30 stars having fin
The probable error IN this work is less than the
tenth Of magnitude. 4 star in Cassi0pea gave
great deal of trouble; the discrepancy in the
observations upon It amounted at times TO half
a magnitude; eventually faint companion was
was long suspected that Gamma CetIs companion
shines by reflected light Il was matter Of great III;
tcTts planet has yet been recognized OUTSIDE OF
tl solar syste The test H. Of course the polarization
Of light Alter forty OF hiy observations the Gamma
Cct determined 10 DC no exception 70 tle gen
eral rule special research 10 obtain quantiIatlve
81 the difference Of light ~ cO0rca double stars
has yielded UNEXPECTEDLY UNIFORM hkuIe' rom
observers, aud shows that such stars yied abundant
lgnt, notwithstanding their color The companion OF
Is estimated TO be 81 about the hihth hdEltud
Iuyc,g atious to ascertain thcr s light Is rejected
or not, are as yet uncOmpcted. The working OI the
double star photometer Is very satisfactory ...,.
Professor Peters agreed In the opinion tat systenac
errors are the to be dreaded lie thought the IN
,tIumeut aud methods described were wei cacuated 10
avoid There IS liability to frequent deception III
seeing companion that do not exist and Professor
Peters has occasionally been temporarily mislead by
telescope ghUsts. good way 10 OBTAIN an AlultOhal
to have made with both eyes, separately and they
are then found differ about mnch as when taken Dy
u Professor Peters, the left eye observations
prove better than the right. In the discussion
which followed Professor Pickering stated that their
phot0metrlc estimate, nude The companion Oi SIRIUS oi
only tentuousaudtn part Of the brightness tqt SIRIUS
ms: but II tie companion shines by reelected light,
mn. bt zen sbnSg pbases Ike tic moon Proics-
g0r Ncwcomo sand that when observing the companion OF
SIRIUS had often thought hc perceived ptCuuaFty OF
shape u II its diameter greater one way than TIE
scryltiuus or that cuWpspon hc had never perceived
any clouguUu OF is shape, or IN TACT, ANY tEuE drr
cnt from Of Ike ,zr Professor rNnudcr Ie-
frcd To tnc supposed CnJu2,s of color IN SIRIUS, ana
-ad that In tho tmo Of itocmy IL was iuuuy OF SUD
red star probably like AdrDdrGu it Is now Of the
purcs white. Professor Peters sad that She references
tat color OF SIRIUS ahous "ncl'h' "l'ts " .l'Cl
fewer Than has been supposed. TIE passage IN Ptolemy
where SIRIUS Is TcCrrOd To As the ruddI may, II Is
supposed, have been copy ist mistake te Greek wolu
used being unlike the word FOR SIRIUS. The error was
pIupALted 1y he ArUDiaUs, VINO repeated TINS mistaken
DESIGNATIONS Professor Peters thinks the evidence Is
yer, qur.unua Die about the alleged change Of color.
Al later hour, Professor Pickering described the
M thoI employed for serving faint objects and satel
ltes The apparatus used Tor double stars Will not an
~yrr the purpose where the companion u exceedingly
faint Professor Pickering exhibited table of the pre-
mipa., results obtained wth four satellites. ~ follows