70 



SCIENCE. 



[N. S. Vol. V. No. 106. 



SOCIETIES AND ACADEMIES. 



NEW YOEK ACADEMY OF SCIENCES. — SECTION OF 



ASTRONOMY AND PHYSICS, DECEMBER 



7, 1896. 



Peof. J. K. Rees gave a very iuteresting re- 

 view of the work of Newton, Evans and others 

 upon the probable orbit and period of the great 

 shower of meteors which were seen in 1833 and 

 1866, and which are soon due again. Attention 

 was also called to the work of Leverrier, and 

 Opholtzer in finally settling the period of this 

 swarm at about 33J years. At the request of 

 Prof. Stone observations were made at all the 

 large observatories, on the night in November, to 

 see if by chance an unusual number of meteors 

 should be observed, thus indicating that the 

 swarm had so scattered out that some of the 

 advanced guard would appear even three years 

 ahead of the general mass. The number ob- 

 served by Prof Eees was no greater than normal 

 and the results were rather negative. 



H. C. Parker, upon a universal method of 

 measuring current, showed how it is possible 

 and convenient to measure currents varying 

 from a fraction of a microampere to a megalam- 

 pere, i. e. , from, say a hundred millionth, to a 

 million amperes, simply using a voltmeter, or a 

 delicate galvanometer, in connection with a 

 series of shunts. He exhibited a series of such 

 shunts ranging from 0.1 ohm to 0.00005 ohm 

 which had been determined with the double 

 bridge with an error not to exceed 0.1^. 



W. Hallock then exhibited some mechanical 

 devices by means of which it is possible to illus- 

 trate the interference of two beams of light with 

 any desired phase difference, and another show- 

 ing how a beam of plane polarized light is re- 

 solved into two beams at right angles to each 

 other on entering a double-refracting medium. 



Dr. T. A. Humason reported upon the me- 

 teors seen on December 4th, as follows : While 

 riding in Central Park opposite West Seventy- 

 second Street, at twenty minutes to five, on the 

 afternoon of December 4th, I saw a meteor so 

 brilliant as to be plainly visible, though it was 

 then about sunset and quite light. The meteor 

 caught my attention at an altitude of fifty de- 

 grees, a little south of east, and descended al- 

 most vertically and with rapid motion, until it 

 reached an altitude of fifteen degrees, when it 



disappeared. The head had a diameter of about 

 fifteen minutes and was very clearly defined. A 

 train, two or three degrees in length, was also 

 visible. The eastern sky was almost covered 

 with clouds and the meteor seemed to be be- 

 tween them and myself, though it is probable 

 that it was above the clouds and was seen 

 through them. Tlie meteor vanished in mid- 

 air, without passing behind any intervening 

 object, and as meteors are usually extinguished 

 within five or ten miles of the earth it seems 

 probable that this was near the end of its jour- 

 ney and not far above the city. 



At the same time people on Brooklyn bridge 

 observed a meteor in the northeastern sky. It 

 is possible that these were one and the same ; 

 and if so, owing to the difference of direction 

 from the two points of observation, the meteor 

 must have been very near. But it is quite pos- 

 sible that the observers on Brooklyn bridge 

 were looking at a different meteor, for an- 

 other was seen at the same time from Fordham, 

 and directly east of that place, which would 

 have been visible in the northeastern sky from 

 Brooklyn bridge. 



At the time these meteors were seen, another 

 was observed passing over Passaic, N. J., and 

 moving eastward ; another over Irvington-on- 

 the-Hudson, moving northeastward, and one 

 over Danbury, Conn., also traveling in a north- 

 easterly direction. It is evident that this was not 

 a single meteor seen from these several places, 

 but that there were several meteors traveling in 

 slightly different directions. As large meteors 

 seldom or never travel in groups and as they 

 are usually shattered near the end of their 

 course, it is probable that this came into the at- 

 mosphere a single, large meteor and that it 

 burst not far from here, the fragments taking 

 slightly different directions. All of these ob- 

 servations would be satisfied by the following 

 hypothesis: Passaic, Irvington and Danbury 

 are almost in a straight line. It is probable 

 that the meteor approached this neighborhood, 

 passing over Passaic and moving eastward ; that 

 immediately after passing Passaic it separated 

 into three or more parts, one turning slightly to 

 the north and passing over Irvington and Dan- 

 bury, another continuing in a straight line and 

 passing over Fordham, and a third turning 



