10 



THE ROYAL SOCIETY OF CANADA 



SuMMAjiY OF Sea Swings. — Ritchie Compass. 



B = xtan I + y jT C = x'tan I + y'^r 



77 - 807=271 - 298 X + 423 - 040y. (1) —21 - 612=271 - 298 x' + 423 - 040 y' 



122 • 478=423 - 040 x + 662 - 686y . (2) —34 - 458=423 • 040 x' + 662 - 686 y' 



from (1) 



121 -325=423- 040 x+ 659 -651y. (3) —33 -700=423 -040 x'+ 659-651y' 



combining (2) and (3) 



1- 153=3 -035 y —0-758=3-035 y' 



...y=: + 0-380 .-.y' =—0-250 



and x=— 0-313 and x' = + 0-310 



The constants for the Kelvin compass were determined in a similar manner 

 and are as follows: 



A=— 1-6, D= + 0-976, E=— 028, 

 x=— 0-537, y= + 0-460, 

 x'= + 0-238, y'=— 0-145. 



