a ip gt Ee ake ee eae 
Ea oe ae REE ee re ees ee Geet 
Chemistry and Physics. 113 
(1.) Arago’s neutral ‘eager often assumes a distinctness which is never: 
exhibited by either of the others, merely because the polarized bands in 
the vicinity of the sun are obscured by the dazzling brilliancy of its 
Tay 
(2.) For the same reason, Babinet’s neutral point is often better de- 
fined, in the morning and evening, than Brewster’s during the middle of 
e day. 
(8.) But when Brewster’s and Babinet’s neutral points are both above 
the horizon, if the sky is clear, the former is generally more easily posited 
_ the o tter. This is especially the case at midda 
every clear day, and on a large portion of the days which are 
coats ctneued by — the position of each of the neutral points 
can be determined. wster records but two days during five years’ 
observations (Phil Mine 7 80, 124), upon which he saw all the points. 
rago’s neutral point often rises before Brewster’s sets. Under 
favorable eee sie the three points are, therefore, some- 
times simultaneously v 
(6.) Halos and stands are @ frequently discernible through the polari- 
scope, which are invisible to t ed eye. 
The i abstract genaies some of the results of the month’s 
observations 
Satisfactory observations were made on 25 days. 
All the neutral points were see Bi” 
There e were no satisfactory observations on 6.2% 
“ 389 obse rvations of Arago’s n neutral point on 25: S 
= iat 5. @ rapes ae 4 aerae 
“es “ce 59 Bre “ 20 ae 
ied. ie weeps point was remarkably "detinct on ; ; 4 
“ 
Prewsten 8 a 11 
Arago’s was the at one observed on ee 
abinet’s 1 day. 
Babinet’s abd Brewster’s the only ones seen on : eg 
rago’s a binet’s “ = 2 days. 
pag ahd pone were simultaneously ree on April 5th, from 45 32’ 
to 4 
B sewilers 5 weaiead point was perceptibly more than Babinet’s at fifteen 
observations, and less distinct at two observations. 
subjoin a few of my notes, which refer to points of special interest ; 
March 8th, 5" 45’, p.m. Near the proper position for Arago’s neutral 
point, the positive and ‘negative polarities coalesce — clouds, with no 
intervening space or neutral line. 
M A. M. 
March 11th, 3550/, p.m. Sky covered with thin clouds. A neutral 
pose in the East, 42° above the horizon, and more than 70° from the 
anti-solar point, with reversed polarization, or positive — and oe 
Au: Joie, Sc1.—Seconp Series, Vou. XLII, No. 124. 
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