252 Chronicles of Science. [April, 



first of these outlying streams occurs about twelve hours earlier, 

 and its passage through the last about twelve or fifteen hours later 

 than its appulse with the main or central current." From other 

 communications respecting the November ^iteteors, as seen last 

 autumn, it would appear as though the distance of the outlying or 

 lateral streams from the main zone had become very much greater, 

 with the advance of the meteors over one year's arc. 



Mir. Proctor supplies a note " On the Sun's Motion in Space, and 

 on the relative Distances of the Fixed Stars of various Magnitudes." 

 It had been noticed by Mr. Dunkin that when the sum of the 

 squares of the stellar proper motions is compared with the sum 

 of similar squares corrected for the effects attributed to the sun's 

 motion, the effect due to the correction does not appear to be so 

 large as was to have been expected. In fact the former sum is 

 142-0251, while the latter is 136-4917, the difference being alto- 

 gether insignificant compared with either. Sir John Herschel had 

 expressed the opinion that this result need not surprise us. " If 

 the sun move in space, why not also the stars ? and if so, it would 

 be manifestly absurd to expect that any movement could be assigned 

 to the sun, by any system of calculation, which would account for 

 more than a very small portion of the totality of the observed dis- 

 placements." Mr. Proctor shows, however, that the mere number 

 of the stellar movements will not suffice to explain the discrepancy, 

 since the motion of each other is affected by the sun's, and so the 

 sum of the corrections is as much increased (through the effect of 

 mere number) as the sum of squares. By aid of the integral cal- 

 culus he proves that the correction should in effect be one-half of 

 the uncorrected sum. He explains the discrepancy as due to the 

 fact that the stellar distances have been incorrectly dealt with, the 

 distances of the smaller stars being overrated. He finds in the 

 observed proper motions of the smaller stars an independent proof 

 of this. 



Dr. Robinson suggests an ingenious method of imitating the 

 transit of a planet over the sun. He obtains an artificial sun by 

 placing a plate of brass, in which is a circular aperture, in the focus 

 of a telescope. When this is illuminated by a lamp placed behind 

 it, and viewed collinator-wise, it appears as a luminous disc 17' in 

 diameter. He obtains an artificial planet, either (1) by means of a 

 small opaque disc, carried by the frame of a micrometer in the ob- 

 serving telescope, or (2) by means of an opaque disc placed within 

 the aperture, and movable in its plane by a micrometer attached to 

 the collinating telescope. 



Mr. Stone supplies a paper on the increase of probable errors in 

 a transit of Yenus, as dependent upon the smallness of normal velo- 

 city. After showing that the differences in time observations made 

 on the transit of Mercury in November, 1868, actually amounted to 



