380 Proceedings of Scientific Societies. 
atitnde. : Longitude. Date. Magnetic Dip. 
Hudson, Ohio, 41° 15'N. 81° 26 W. ‘April 15, 1840, 72° 53.2’ 
Aurora, agate | Me 81 2 Sept. 8,7 . 42 Dow 
Windham, “ 41 15 81 03 Oy ae, ee 
Bazetta, aT 0 oi <9 ** 2 ot 
Kinsman, "41 oO 80 34 Peer ere: 
Hartford, oS: Ae 80 34 ~ ih 
Warren, <r 20 80 49 ts eee 
Cleveland, = -4hg 30 81 42° ~ ye 
Bedford, eee 81 32 oe See Se 
Twinsburgh, “ 41 20 81 26 pie ee 
Tallmadge, “ 41 06 81, 26 yo. ese 
Shalersville, “ 41 15 81 13 Oct. 15, “ 42 °500 
Streetsboro’, “ 41 15 81. 20 AO oe a ee 
Tallmadge, “ 41 06 81 26 "jake. te oe 
Mr. Walker read a communication, entitled “ researches concerning 
the periodical meteors of August and November, by Sears C. Walker,” 
which was referred to a committee. 
Prof. Bache brought before the society an instrument for measuring the 
changes in the vertical components of the force of terrestrial magnetism, 
which he described as combining the principles of the vertical force in- 
stroment of Prof. Lloyd, with that of reflection adopted in the magnetom- 
eters of Prof. Gauss, and which had been made for him by Mr. Saxton. 
Prof. Bache stated, that having found difficulties in the use, especially. 
by his assistants, of the vertical force instrument invented by Prof. Lloyd, 
and made for the magnetic observatory at the Girard College, by Robin- 
son, of London, he had applied, in June last, to Mr. Saxton, to construct 
the instrument now presented to the notice of the society. The details 
had been matured by conference with Mr. Saxton. The magnetic bar, 
placed and supported as in the instrument of Prof. Lloyd, carries a mirror 
upon its axis. The mode of adjusting the position of the centre of gravity 
of the needle does not differ materially from that adopted in the instru- 
ment referred to. The needle is raised off the agate planes by the action 
of a screw, raising a bar which supports two small cups adapted to receive 
two projecting pins on the arms of the magnet. This magnetometer Is 
observed from a distance, like those of Prof. Gauss. Prof. Bache eX- 
plained the mode of adjusting the instrument, and of placing the scale and 
telescopes. 
Prof. Bache called the attention of the society to a diagram represent 
ing the changes of magnetic declination, as recorded at the magnetic ob- 
servatory of Mr. Bond, at Cambridge, and at the Girard College, on the 
magnetic term day of May, 1840, and showing that the changes attending 
the aurora are not peculiar to one locality, but that, as observed at differ- 
ent places, they are parts of a great magnetic disturbance. 
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