132 ' A. ÏAKAKA.DATE. 



OX OH . -u • ^ do 



dç> dip d<p 



OY OH . . ,,, . i)o 



0/ o;. i)f 



OZ OH , >, , ,T .. /, 0^ 



-ör=-or^s^+"'^^"^^r 



J^= JH ^ j^ ^^^ ,0^ 



0^ 0^ Oç? 



After computing the vertical variations of the rectangular com- 

 ponents in this way, those of the observed elements '\ ^, H, can 

 couvenientlv be found as follows : — 



OH 



dz dz 



. OX , . , OY 



= cos () - 4- sin u 



dz i)z 



Or) , _, Y" 



= -."t'' 



os ~ âr ° X 



cos o / OY , . OX \ 



=^H-\-o^-^°'^-o.rJ 



00 ^t<'-^ '^^ 



^dz~~l)z^ ° H 



cos ( O'A , ,. Oil \ 



-^l-oir-^^^-oT-j 



cUid —4 — = -^ — Hsec^? 

 Oz Oz 



The reduction to the sea level of § 8 ^Yere calculated by these 

 ibrnudai using the hrst approximate values used for deducing 

 the annual variations. 



.Tables XX to XX Y give data and values of these varia- 

 tions for Ja})an, Austria and Hungary, and Great Britain, at 



