•40 REPORT—1847. 
On the Results obtained bij Avtomatic Registration of the Decimal. 
Bg C. Brooke, M.B., F.RS.y F.R.C.S.E. 
rijc principal object of Mr. Brooke’s communication was to eiplain tbeniMB 
tif iliaturbances which have been recorded in hi» photographs, obtained by iwa- f 
the npparatua of which n description has bwti lately pui)li 3 hed in the Phlacp.-j 
TmnaactiDns. Oftbese disturhnnccs four principal varietieswere desciW. hi: 
firat, which has been ot must frequent occurreuce, the disturbing caus pi. ; 
arrives at a maximum value, ond again gradually diminishes, thus produoop- : 
or leas decply-indcnted undulation in the line; the period of doralica oftoi 
u”***i’*'®®'^**^**^ hours. In the second, which is cotaponti’dynct, 
the disturbing cause comes into full operation instantaneously, and aftermafctft 
unifonn for periods varying from a few seconds to half an hour, ahnipj^n» 
leaving the magnet free to return to its former position. The angiisTvaloiofcw 
last disturbances has rarely exceeded 10', and by them the decliuadon b iatri* 
iiicrenscu. In the third kmd, the miicoot is sudJeoly thrown intorihnJiJiib* 
Its mean place, and U grailually brought tn rest bv the damper in 
from l to 20 ''. Several of the photographs, it was observed, detnoustraadlb*^ 
that a much shorter period waa occupied in brineing the magnet to rtst 
mercury damper described in the paper alluded to, than with the oil 
in be earlier experiments. In the fourth varictv of disturbances, the ma^p' 
lienees vibrating about its mean jilacc, by gradually increasing osdllirtioBJ,*^' 
or reaching a maxiinura, gradually snbsidc. The greatest ampKluifc ofwcilbiw 
rarely exceeds 4 or 5', aud the duration from about 3 “ to 15“. Mr. Brooke sW 
uiat a Tendon thoroughfare Jiaviog been the locality of all the obsen-atiois.. bft 
no consider the reality of the two last varieties of disturbance free from iluubt: “ 
iwint however could not be settled until sufficient evidence has bemoltaiw*^ 
•ituauons least liable to purely local disturbance. He also remarked. thatslM 
i^e comparison of many hundreds of ob-wrvations showed an exact accutitf 
^tween the movemenU of the magnet at the Koval Observatorj-, and tie 
1 K ii'filances the difference in the amount of disoirbinj f«»» 
the two ic^alitics was not less remarkable. 
pn-iodic method of registration was proved brsreS^ 
nf rKn ^ * '■CRisters, in wliich, at diflVrent periods of the same day, tb«vjn»^ 
by the continuous line to he esseniLallv differeol Oj^;; 
or in« » ’ "‘‘bough the outline formed by joining tl.e consecutive pointe at utaflk 
Mr n.° I “"y .. 
Ii'nrtK fiC r hy explaining a simple method of subdividing / 
diflerciit rPcrUw! twelve hours (which, from the unequal 
or more ivin I **^*.1” '‘‘■pug. varies sometimes as much as 0-2 in. in 
cJoSo!?. of dividing the scale on a strip 
bv a screw * m • attached to two pieces of wood sliding 00 a b« W 
i-g the cqu'alily of tSe SwliL'.'’" ““ ' 
On Anemometers and Resolvinff Stoles. By CapL Cockbubs. R-^' 
at sea attention to the advantage of a correct registration 
the crstruction of Dr.^Robinson 
ticulnr bp ho- ko make it applicable to use in the navy. r . 
S. of Prf.fc. 50 r Wb, orrooged a ' 
'^‘^I'^P’^ature of Ihe Earth at Tr«an(lnat,iff^ 
Skills i"l Caldecott; Eaq. B,j Profesor J. D- 
*rh * 
twelve Frcn^ch'fppf by means of three thermometers, 
‘Continued four those placed at Edinburgh and .jjj; 
»«t.r times a day for about three years. An extended exUact s' 
