THE OBSERVATIONS OF DEFLECTION. 151 
hardly be remarked that it is sufficient to take into account the 
first decimals of the values of g and 7. 
TABLE. 
q- T. | Xe | q- Wa 
0-33333 0°33333 0°30 0°45921 0°21406 
0°33757 032911 0°31 046322 0-21048 
0°34181 032489 0°32 0°46721 0:20694 
0°34606 032068 0:33 0:47118 0°20343 
0°35031 0°31648 0°34 0:47513 019996 
035456 0°31229 0°35 0-47906 0-19652 
0°35882 0-30812 0:36 0:48297 0-1931] 
0°36308 0°30395 0°37 048685 0°18975 
0:36734 029981 0-38 0°49071 0°18641 
0°37160 0:29568 0:39 0:49454 0°18311 
0°37585 0°29156 0-40 0-49835 0:17985 
0°38011 0-28746 0°41 0-50214 0°17663 
0-38436 0:28338 0°42 0:50590 0°17344 
0°38861 0:27932 0°43 0°50963 0°17029 
0:39285 0°27528 0°44 0-51334 0°16718 
0:39708 0:27126 0°45 0°51702 0:16411 
0-40131 0:26727 0:46 0-52067 0°16107 
0°40552 0:26329 0°47 0:52430 0°15508 
0°40973 0°25934 0:48 0:52790 0°15512 
0°41393 0°25542 0:49 0-53147 0°15220 
0:41892 0:25152 0:50 0°53501 0-14931 
0°42230 0:24764 0°51 0.53852 0°14647 
0:42646 0°24379 0°52 0-54201 0°14367 
0°43061 0°23997 0°53 0°54546 014090 
0°43474 023618 0-54 0-54889 0-13817 
0:43886 0:23242 0°55 0°55229 0°13548 
0:44297 0°22868 0-56 0:55566 0°13283 
0°44705 0:22498 0-57 0°55900 0°13022 
0°45112 0-22131 0°58 0°56231 0-12765 
0:45517 0°21767 0°59 0°56559 0°12511 
0-45921 0-21406 0°60 0:56884 0:12261 
: 8. The fundamentai assumption in our theory, 7. e. that the 
_ three changes take place instantaneously, is never rigorously 
fulfilled in practice, although in the case of deflections by gal- 
vanie currents the time required for each change may be re- 
_ garded as insensible. But in the case of deflections by mag- 
netic bars, the time is always more or less considerable, in pro- 
portion to their size and weight. With bars of 25 lbs. some 
seconds are always required to complete the change; especially 
when it is a complete inversion, and not merely a change from a 
