M A0NET1C B S E R VATION S. 

 Horizontal Intensity. Observations of Vibrations. 



107 





Magdalena Bay, June 9, 1S66. 





San Francisco B 



\y, June 26, 1 



866. 



No. 



Time A. M. 



No. 



Time A. M. 



Time of 150 

 vibrations. 



No. 



Time A. M. 1 No. 



Time A. M. 



Time of 150 

 vibrations. 



o 



X b 8 ,o 5 ,. 4 



150 



I" 2I"> 52\8 









3 h 2i°> 22\7 150 



31. 36- S7 .. 7 



'5 m 35"-° 



10 



1 S 59.4 



160 



1 22 49.0 





10 



3 22 24.7 100 



3 3$ 0.0 



'5 35-3 



20 



1 9 54-5 



170 



1 23 44.4 





20 



3 2 3 2 7- 2 



170 



3 39 2 -5 



'5 35-3 



3° 



1 10 49.0 



1 So 



1 24 40.2 





3° 



3 24 3°- 2 



1 So 



3 40 4-7 



'5 34-5 



40 



1 11 44.4 



190 



1 25 36.0 





40 



3 2 S 3 2 ° 



190 



3 4i 7- 2 



• '5 35-2 



5° 



1 12 39.8 



200 



1 26 30.8 





5° 



3 2 6 34-7 



200 



3 42 10.0 



'5 35-3 

























Extreme scale readings, 









Mean .... 



15 35-'° 





At beginning .... 55'° — 101.0 



Extreme scale readings, 





At end 69.0 — 85.0 



At beginning .... 57.0 — 102.0 





Temperature 79°'° 







Time of one vibration . . 5 8 -527 



Coefficient of torsion . .^ = 4.35 div. 



In 



this and the following observation the vibrations of 





the magnet were very irregular on account of a high wind 



Time of one vibration . . 6 s . 234 



whic 



l shook the instrument. 





Magdalena Bay, June 9, 1866. 



U. S. N. Observatory, Washington, Nov. 1, 1866. 



No. 



Time A. M. 



No. 



Time A. M. 



Time of 150 

 vibrations. 



No. 



Time P. M. 



No. 



Time P. M. 



Time of 150 

 vibrations. 







I h 4I m I2 S .2 



150 



1" 55- 4"-S 









5i> 19" 52«.7 



MO 



5 b 37 m 4»'-S 



17™ 53'- 8 



10 



I 42 7.8 



160 



1 56 0.4 





10 



5 2 > 5-o 



160 



5 38 58.0 



17 53-0 



20 



1 43 3-o 



170 



1 56 56.0 





20 



5 22 16.0 



170 



5 40 9-2 



■7 53-2 



3° 



1 43 59-o 



180 



1 57 5'-4 





30 



5 2 3 2 7-5 



180 



5 41 20.7 



■7 53-2 



40 



1 44 54.0 



190 



1 5S 46.4 





40 



5 24 39.0 



190 



S 4 2 3>-8 



17 52.8 



5° 



1 45 48.4 



200 



1 59 41.6 





5° 



5 25 50.7 



200 



5 43 43-° 



■7 52-3 

























Extreme scale readings, 









Mean .... 



17 53-°S 





At beginning .... 53.5 — 98.5 



Extreme scale readings, 





At end 



At beginning .... 52.5 — • 106.0 





Coefficient of torsion . . ^ = 4.37 div. 







Temperature 86°. 5 



Coefficient of torsion . . v = 5. So div. 





Time of one vibration . . 5 8 . 533 



Time of one vibration . . 7 s . 154 







The following sets of observations of vibrations were 







made in the basement of the Observatory, where there is 







much iron, and are to be used only to determine the moment 







of inertia of the magnet. 





San Diego Bay, June 15, 1866. 



Set 1. November 2, 1866. 



No. 



Time P. M. 



No. 



Time P. M. 



Time of 150 

 vibrations. 



No. 



Time. 



No. 



Time. 



Time of 150 

 vibrations. 







6 h n m 9 s . 2 



ISO 



6 h 25™ 58". 2 I4 m -i 9'-° 







5 h 37 ™ 3 i..7 



Mo 



5" 54 m S3'-8 



I7-22M 



10 



6 12 8.3 



160 



6 26 56.6 14 4S.3 



10 



5 3S 4i-2 



160 



5 56 3- 2 



17 22.0 



20 



6 13 7-4 



170 



6 27 55. S 14 48.4 



20 



5 39 5°-7 



170 



5 57 12.7 



17 22.0 



30 



6 14 7.0 



1 So 



6 28 55.4 14 48.4 



3° 



5 41 0.2 



180 



5 58 2i-5 



17 21.3 



40 



6 15 6.2 



190 



6 29 53.S 14 47.6 



40 



5 42 9-7 



190 



5 59 3'- 2 



17 21.5 



50 



6 16 5.4 



200 



6 30 53.0 14 47.6 



5° 



S 43 '9-2 



200 



6 40. 7 



17 21.5 





Mean . . . . | 14 48.22 





Mean .... 



17 21.73 





Extreme scale readings, 



Extreme scale readings, 





At beginning .... 94.9 — I0S.9 



At beginning .... 59.1 — 99.8 







At end 66.9 — 92.2 





Coefficient of torsion . . v = 3.60 div. 









Time of one vibration . . 6*. 945 





Time of one v 



bratio 



> . . S a .92l 















