374 ANNUAL OF SCIENTIFIC DISCOVERY. 



to be on the increase. Several days or periods in the year appear 

 to have been rich in aerolitic and first-class meteors. Some of these 

 are, January 2d and 10th; February 6th and 18th; March 1st and 

 7th; April 19th; June 1st and 2d; July 17th and 29th; August 3d, 

 7th, and 12th; September 10th; October 1st, 3d, and 23d; Novem- 

 ber 9th-13th, also November 29th; December 8th-13th. With 

 regard to the November period for shooting stars, Mr. Herrick, of 

 New Haven, considers it to be advancing into the year at the rate of 

 three or four days a century, the period of maximum being about 

 thirty-three years; Mr. Greg, an English meteorologist, however, 

 considers it may be nearer seventy. If Mr. Herrick is correct, then 

 the November period should again culminate in 1866. 



Prof. A. C. Twining, in the November (1861) number of SHUman's 

 Journal, gives the following conclusions, as the result oWiis investiga- 

 tions respecting periodic meteors, and especially as regards the radiant 

 of the August meteors : 



First. The position of the radiant is probably capable of a far more 

 exact determination than is ordinarily supposed, or than could have 

 been anticipated. 



Secondly. The radiant is apparently subject to a motion of several 

 degrees from day to day, and one which exhibits some remarkable 

 points of agreement in the comparison of one year's position with 

 those of other years. 



If asked, says Professor Twining, what this radiant is, whose posi- 

 tion can be marked so definitely, I reply, It is not a point of exact 

 apparent divergence of all the conformable meteors, but it is such a 

 point for the great mass, or assemblage of them, so far as one ob- 

 server can judge ; and it is also, under the same visual limitation, the 

 centre of that area within which the others would project back their 

 lines or directions. The process by which it is found has been, in my 

 own case, the following: The first few meteors, say five or seven, 

 determine the locality rudely. Fixing our attention primarily upon 

 this locality, we are soon supplied with some contiguous and very 

 definite flights which cut the area in a line that can be traced and 

 kept in mind. It may be that this line will be shifted laterally by 

 other nearly parallel flights. We next look with interest for other 

 flights crossing the first at right angles, or at a large angle ; and, 

 when a few such are obtained, they limit our area to a narrow cen- 

 tral space, subject only to slight shiftings one way or another, accord- 

 ing to judgment, continually and rigidly exercised in view of the 

 successive flights which can be brought into comparison with it. 

 These flights should not ordinarily be very distant from the central 

 area. In fact, the very abbreviated streaks almost in immediate 

 proximity to the radiant are of special value in the determination or 

 the verification. Occasionally, indeed, a meteor will show itself sta- 

 tionary in the very radiant itself. In the year 1855, on the night of 

 August 10th, such a stationary meteor appeared and almost instantly 

 disappeared in the spot to which my sight was directed, with a pecu- 

 liar effect, as if a new fixed star had suddenly begun its existence, 

 and as suddenly ended it. Not many minutes after, a second came 

 and went, with a like singular and bewildering effect ; and, while I 

 was in the act of pointing out its exact position to a fellow-observer, 



