Intelligence and Miscellaneous Articles. 157 



Brewster's neutral point was perceptibly more distinct than Babi- 

 net's at fifteen observations, and less distinct at two observations. 



I subjoin a few of my notes, which refer to points of special interest. 



March 8, 5 h 45 m p.m. — Near the proper position for Arago's neu- 

 tral point, the positive and negative polarities coalesce upon clouds, 

 with no intervening space or neutral line, 



March 9, 6 h 25 m a.m. — Hazy, and polarization fluctuating. 

 10 ll 40 m a.m. — The polariscope showed a brilliant halo around the 

 sun, which I had not before noticed, but which was afterwards barely 

 visible to the naked eye. 12 h 10 m p.m. — Haze continues. Negative 

 polarity remarkably distinct over the face of the sun, and for several 

 degrees north and south. 



March 11, 3 h 50 m p.m. — Sky covered with thin clouds. A neutral 

 point in the east, 42° above the horizon, and more than 70° from the 

 antisolar point, with reversed polarization, or positive below and ne- 

 gative above. 5 h 25 m . — A similar point still observable, but about 

 5° nearer the horizon. 



March 12, 6 1 - 30 m a.m. — Cloudy. Polarization positive from east 

 and west horizon nearly to zenith. A similar observation was made 

 March 21 at 6 h p.m. 



March 17, 9 h 15 m and 10 b 40 ra a.m.*, and March 18, 10 h 30 m 

 A.M.f — Very clear. Sun so bright that I was unable to detect the 

 negative polarity between Babinet's neutral point and Brewster's, 

 even by screening the eye from the direct light of the sun. 



March 19, ll h 5 m a.m. J — Halo, visible only through the polari- 

 scope. l h p m. — Snowing. 



March 20, 5 h 25 m p.m. — Cloudy. Polarization in horizon every- 

 where positive. 



March 24 to 28 inclusive. — On each of these five successive days 

 Brewster's neutral point was remarkably distinct and beautiful. 



April 3, 5 h 40 m p.m. — Cloudy in west, and polarization positive 

 from zenith to horizon. 



Strong reflexion sometimes changes the character of a compara- 

 tively weak polarization from positive to negative, or vice versa. A 

 fainter reflexion, by showing whether the bands are interrupted or 

 continuous, often aids in determiningthe character of the polarization. 



The increased refraction of a piece of glass interposed between 

 the polariscope and the sky will frequently show a neutral point 

 which is otherwise invisible. 



The normal polarity is often reversed by a stratum of clouds of 

 uniform thickness, especially within the solar primary lemniscate. — 

 Proceedings of the American Philosophical Society, vol. x. Feb. 1866. 



BY CHIEF JUSTICE COCKLE, F.R.S.§ 



This inference |[ seems to me to be erroneous, unless we impress 

 an arbitrary constitution on the fluid, and have recourse to the unne- 



* On steamboat in Raritan Bay. 



t At Eagleswood, near Perth Amboy. J In New York. 



§ Extract, communicated by the Author, from a Memoir read to the 

 Queensland Philosophical Society on Mcnday, April 30, 186G. 



|| i. e. the inference of Ostrogradsky that tiie shell will be in equilibrium. 

 His paper in the Petersburg Transactions is reprinted in Taylor's ' Scientific 

 Memoirs.' 



