New-York daily tribune., 1859-08-05
ASs OCIATIOE FOR THE ADVANCEMENT
OF SCIENCE.
fom Or Ova Repor.e-G
MORNING SESSION
SrRIscruIp, Thursday, Aug. 4. 1853

a. H. the minutes read. and Q number OF new nem-
beIs elected. An invitation from the Railroads to
Amherst for an excursion Saturday, was received
ard accept.d the ladies' Of Amherst also offering
collation. ard the College inviting to al examination
CT their collections Of Natural History.
Sun6rv announcements of q business character
were made The report of tie Committee on the
Coast Survey was accepted without reading, aud 10
ier1ed TO the Standing Committee, with power TO
print. Prot. COFFIN moved an amendment 10
the rues concerning the sotou Of the Committee on
Pubhca.:or curtsilng their power, By rot allowing
them 10 emit the titles Of rejected commune shons
The al irert was referred TO The Standing Com.
mstee TO report tomorrow.
SECTION or NAIHENATIcs.
Nominating COMMITTEES, consisting OF Messrs'
Ptroe Horsioro Trowbrdge, aud Coffin, was elect'
ed. Prof Wm Glieepie, o: Schenectady 81 chosen
Chairman Of tic day aud the Section proceeded mme-
d:ately 70 scientific business.
Prof A. ID. B.oHr offered discussion Of some cb
sery ations of magnetic declination or variation.
TLs be anrounced az tie frat Of series ct discus
scns Of TIE mag uetic and meteorological observations
made urdor hs direction, at the GIrsrd College OBJ
sey story, between 1870 and lS5, ard published oy
order o the Sps;e o the United States. referred 20
the ten or e, ven years period in the AMOUNT OF regular
ard daily charge in the position Of the msgnetc nee
de ard in the disturbances to which that change Is
liable.
Tie method Of discussion is similar to that pursued
by Gen Sabine in his discussion Of the oDservatiocs OF
tno British magnetic observations.
The frs. step 10 separate the regular daily move
mert of the reeGle from the disturbances In erecting
this the criterion of Prof PeiIce La. been applied 20 as
70 rtoye al arbitrary assumption from the discussion,
the formula showing the limits and variation from the
mean beyond which the observatiors were to be
ciassed disturbances Taking out these results the
Of those remaining gives the regular OF pornai
chsnges for each Cay for the mean Of the days OF
esch year. TLese represented by 'essei formula
ard tie application Of the method Of least siusres,
| ard the derived curves shown upon diagrams.
IL curves quite regular in Showing two Haxin
| ard minima Of magnetic ceciination curing the a
hours tie great movement Of the needle from eaf 10
west, or from the principal minimum to the pnnclpsl
maximum, taking place between I:3o N The morning
and 80 in the afternoon. The lesser maximum ana
minimum are in the hight period. This excursion ot
| The ueede al mean Of the whole year in lSiO was
rre mirues of arc, ard in 1915 eight inmates and
| half. TIE table showing the change Tor the seyefs
| years Of observation presetted Bunbers regularly
diminishing until 1913, and thea increasing to ioiJ.
diagram illus.rsfed this change, showing clearly the
eleven. year period De, elcped by the observations "A
special formula gives May, 1913, as the epoch OF the
| niDum.
The discussion next took up the disturbances ard ex
an med the results from the number OF disturbances
| and their ma gpi,ude. Tho whole number OF disturb
arce observs'ions discussed was 21', being about
OF e-teb,h of tie whole number O observations made
| nsmely sec. The disturbance were separated
into eastern and western, and some curious results de-
duced ss to their maIims and mlnma during te year.
The table shows two maNims, one IN August and one
in Auril and two mniIna, one IN FEBRUARY ahd tho
| other in .Iure.
The table of number of disturbances for the several
wears Of observation hoes not bring out the eleven year
period clearly as the former part OF the discussion
| but iIdic ates il, nevertheless, sufficiently.
| The Lumber Of disturbances ranged according to
| hour of tie day show maximum at a. m, and q
minimum at 2 p. M, and develop the curious result
| that the westwardy disturbances are maximum az
| -. arl tpI InIm
vice versa. This agrees with the result already oo
ts,red by Gen. SABINE tor Toronto, and rule, the
deductions from the observations at the two pcsil1es
remarkably accordaIt Their paTsLeiIpns sna ai'
| terences were carefully compared by Prot bache
The amount OF til disturbance ID the different years
shows the eeven-year period, not only in the average
Of the Western and Eastern disturbances, but IN each
Of them separately. special forrnIla applied to the
numbers Of the table gives August is3, as the epoch
Of the minimum Combining this result with the former
from the amplitude Of the decbnation change, June,
1873, may be regarded as the epoch OF the minimum.
| The magnitudes classed by months, show the same
general laws as the numbers, namely, two maxma, IN
October Sud April, ana t@o mnima, In February ana
june. Clsssed by hours of the day, the magntudes
| show p. III. minimum, ard 10 p. m. maximum,
the maxim Of eastwsrdly disturbance az minimum
Of westwardy again corresponding to each other at
| 8p. m. The law governing the disturbance Is thus
shown TO be Of systematic character and the curve
for which diagram was given, placed upon thai OF
the reg uiar diurDs changes would eproouce what IS
buown as the mean durnal variation" of the declna-
lion. This disturbance variation has but one maxi
| mum and AID ore minimum in the twenty -four hours
| while the regular change of decoation has two.
The discussio closed with comparison OF the re.
suits thus independently dednced %lth tho'e derived
| by Prof. Il Wolf from observations OF the frequency
OF the solar spots The numbers OF Prof Wolf are re-
produced almost precisely from the Grard College ob.
| seryatons no difference exceeding two-tenths OF
minute occurring in the computed and observed mag
| nude of the daily charge Of magnetic varatlon
This branch OF inquiry Is o great interest Ia con-
| terrestrial na0retl-m with general COS
| ulcal phenomenal
| P,of. CorfIy inquired whether the observa.
tions Mt Grard College had been compared with those
| ON otler continents Prof BhcHE replied thst while
observations contpen. and one Zone were easily
compared those different continents and In different
zones varied 90 much as to mske the comparison very
difficult OF course, if the eleven.years period has
real connection nth the solar spots may be expected
TO be found in all Terrestrial magnetic observations
In reply 10 question, Prof. BicHE stated that Won
eleven years period in spots on the suo was derived
| from over 20 years observation Some conversation
anorg various meu bers followed the great interest OF
this bel wee the solar spots and terrestrial
magnetism. In ply to some inquiries OF Prof
Prof BAcHE end Prof PIERCE explained The nature and
design Of Peices criterion, used to such advantage
by Mr Schott apd showed how entirely Prof. Airy Of
Cambridge England, had misunderstood the founda-
tions and spirit Of th. valuable addition to our means
| Of reducing observations. T5s criterion is simply
Inc ans If determining from fundamental principles OF
| pobabi " whether observation is to be rejected
whether the probability of result IL increased or
din insbed by rejecting that observation. All the
computations in toe Coast Survey and IN the American
NAUTICAL Almanac, TO which the criterion il appE
cable are row made by its aid and the various COM
puters always ready to pick flaws in the methods pro-
osed to item, have unanimously acknowledged the
! lIestimable value Of this method OF Peirce:
A paper on Ocean Currents, by Capt WILSEs, was,
| in biz absence read by title.
Prof BRocALEsLY, Of Hartford, gave an account Of
some ohsery ations Ozone Indicating that the guam
tty of Ozone increased with the increase Of moisture
of the air And was slightly greater in the 1t than in