AMEKICAN INSTITUTE. 495 



frequently ; but it requires three or four months for such oil, when used 

 with paint, to dry. 



Mr. Seeley showed that if the hydrogen left, the oil must weigh less; 

 but the fact was, that oils in drying do not, like water, evaporate ; linseed- 

 oil oxydizes, and, consequently, takes more matter into its svibstance, and. 

 therefore, the skins of paint are more dense than the paint before drying or 

 oxydizing. The use of an alkali to cut up the skins of pairtt having been 

 alluded to, I would suggest that such a practice as making the oil of paint 

 into a soap, with alkali, is an absurd practice. The oil is not soluble in 

 water ; but the soap is, and therefore, the paint will wash off if prepared in 

 such a manner. 



Several observations made, while using different kinds of paint, were 

 given by gentlemen in the meeting, upon the advantage of suitable weather 

 for outside work ; the temperature of the paint, and of roofs, when it is 

 applied, &c., and upon materials used in roofing. 



The subject for next evening was selected — Mr. Howe to read a paper on 

 Musical Instruments, particularly the flute. A gentleman, who has in- 

 vented an improved one, is expected to give an exhibition of its power and 

 compass on next evening. 



The Association then adjourned. 



Polytechnic Association op the American Institute, ) 



November 2M, 1859. J 



Mr. Stewart in the chair. John Johnson, Esq., Secretary, pro tern. 



[The following communications were handed in to the Polytechnic Club 

 by Judge Meigs :] 



the aurora borealis op august 28, 1859. 



I observed it throughout, and was convinced that the upper coruscations, 

 were far above our atmosphere, to which the general theory is that it is 

 confined. Light penetrates all space, and as the Aurora is formed of the 

 same elements, there is no reason for its being confined to our fifty miles of 

 atmospheric air. 



From observations made as far south as Havana, I projected a quadrant 

 from north pole to equator, from the angles of observations reported. I 

 found the highest point of the aurora to be, by calculation, about four 

 hundred miles. 



The question was considered by others. The Franklin Institute Journal 

 reports an opinion that the highest points of the radiation or streamers was 

 596^ miles, vertical to latitude 36 deg. 47 min. north. 



I recorded my observations on the meteoric shower of 1833, when, for 

 the first time,^I noticed that the centre of radiation was from a point about 

 15 deg. southeast of our zenith — 40 deg. 41 min. — This account of mine 

 has been republished in England, word for word, without my name attached. 

 I remarked the same peculiar fact at the aurora since that ; it was on the 

 28th of August. 



