284 Mr. Ellis on the Corrections for Latitude 



TABLE I. 



[May 18, 



NOTATION (CAPITALS, lower station ; small letters, upper station). 



B, b units of length of any kind, height of barometer. 



B', b' the same reduced to 32 Fahr. 



A, a deg. Fahr., A', a' deg. Cent., A", a" deg. Eeaum., temperature of air. 



M, m ,, M.',m' } M", m" temperature of mercury. 



H, h feet, B^, A x metres, H 2 , h 2 toises, height above sea. 



V, v V 1( v l V 2 , v 2 correction for height. 



E E! E 2 mean radius of earth. 



log E=7'3199534, log R^ 6-8039605, log E 2 =6'5141407. 



L degrees, mean latitude of the two stations. 



*=-000039 . (M-m)=-00007 . (W-m') = -000088 . (M"-m"). 



T=A+a+836; T'=A'+a'+500; T"=A"+a"+400. 



W=log B log b-t=log B' log b'. 



log G=log 60309-19 -log 900-log (1- -00263 cos2L). 



log G' =log G+0-25527 

 log G"=log G+0-35218 

 log G x =log G+9-48401-10 

 log G 2 =log G+9-73928-10 



1 metre =3-28090 feet, 1 toise 



log G 3 =log G+9-83619-10 

 logG 4 =logG+9-19419-10 

 log G 5 =log G+9-44946-10 

 log G 8 =log G+9-54637-10 



6-39459 feet, 1 toise =1-94904 metres. 



log 3-28090= -51599, log 6-39459= -80581, log 1-94904= -28982. 



FOEMUL^E. 



Log G is found from the latitude in Table II., without interpolation. 



V, v ; Vj, v 1 ; V 2 , v. 2 are found from the nearest number of thousand feet, two 

 hundred metres, or hundred toises in H, h, "K v h v H 2 , k 2 respectively, by Table II., 

 without interpolation. 



Make fresh observations when the temperature does not decrease about 4 Fahr., or 

 2 Cent, for a fall in the barometer of 1 inch, or 25 millimetres respectively. 



