MAGNETIC OBSERVATIONS. 



47 



Log. u. 



Log. tan u — Log. u. 



Log. «. 



Log. tan « — Log. «. 



8.0000 



6-46373 



2.1159 



6.46394 



I-434I 



6.46374 



2.1261 



646395 



1-5957 



6.46375 



2-I358 



6.46396 



1.6874 



6.46376 



2.1452 



6.46397 



I-75I7 



6.46377 



2-I54I 



6.46398 



1. 8014 



6.46378 



2.1626 



6.46399 



1. 8414 



6.46379 



2.1708 



6.46400 



1.8756 



6.46380 



2.1787 



6.46401 



1.9047 



6.46381 



2.1864 



6.46402 



1. 9310 



6.46382 



2.1937 



6.46403 



1-9538 



6.46383 



2.2008 



6.46404 



i-975° 



6.46384 



2.2079 



6.46405 



1-9934 



6.46385 



2.2146 



6.46406 



2.0111 



6 463S6 



2.2209 



6.46407 



2.0274 



6.46387 



2.2271 



6.46408 



2.0426 



6.46388 



2-2332 



6.46409 



2.0565 



6.46389 



2.2393 



6.46410 



2.0700 



6.46390 



2-2453 



6.46411 



2.0824 



6.46391 



2.2509 



6.46412 



2.0941 



6.46392 



2.2565 



6.46413 



2-1055 



6-46393 







The following are specimens of the forms employed in recording and reducing 

 the observations of vibrations and deflections. 



Horizontal Intensity. 



Observations of Vibrations. 



Station, Acapulco, Mexico. Date, May 30th, 1866. Magnet C. 32. Inertia ring No. 



Chron. Fletcher 906, rate, i s -38 losing on mean time. 



Number 



of 



vibrations. 



Time. 



Temp. 



Extreme scale 

 readings. 



Time of 

 150 vibrations. 







8" 3 2 m 3 s . 8 



87 



57 4 -8 



I02 d .2 





10 



8 3 2 57-o 











20 



8 33 5o.6 











SO 



S 34 43-9 











40 

 5° 



8 35 37-° 

 8 36 30-6 











IOO 



8 40 57-2 











I50 

 l60 



8 45 23.4 

 8 46 17.2 









i3 m i 9 s .6 

 13 20.2 



170 

 l80 



8 47 10.2 

 8 48 3-7 









13 19.6 

 13 19.8 



I90 



8 4S 57-o 









13 20.0 



200 



8 49 5°-5 



9i 

 89.0 



65.2 



95-° 



13 19-9 





Means, 







13 19-85 



Coefficien 



t of torsion. V 



ilue of one scale div. = 



2'. 349 



Tor. cir. 



Scale. 



Diff' 





V= S'.o 



Log's. 



300 



8o d .i 



->& A 







30 

 2IO 



83-5 

 76.7 



80.1 



3 -A 



6.8 

 3-4 





5400' + v' 

 5400 (ar. co.) 



3- 733°4 

 6.26761 









■ + T 



0.00065 



Mean = v= 3.40 



