THE LATITUDE-VARIATION TIDE. 
119 
and may write the latitude-variation tide at San Francisco 
mm. 
17.41 f 360° , / 123°\ 1 
±2.11 C0S i 437.4 ±1.8 (±12 ) }’ 
t reckoned in days from September 21, 1872. 
Minimum, 1872, July 14 zb 15. 
Maximum, 1873, February 18 zb 15. 
Preliminary Results at Pulpit Harbor , Maine. 
t) r n _ +n+ . _ f latitude, 44° 09'. 
Position of station j longitude) 68 o 63 ,_ 
Civil date — February 3, 1879 
Julian date = 2407384 
d. d. 
Period = 424.9 ± 2.2 
ft. in. mm. 
a 1 = 0.041 = 0.49 = 12.5 = 0".12 
zb 10 zb 12 ±3.0 zb 3 
= 41° zb 8°, 
and the tide may be written 
mm. 
12.51 _ f 360 / 41°\ ) 
± 3.0 j ‘ \ 424.9 ±2.2 4 _ (±8 ) }’ 
t reckoned in days from February 3, 1879. 
Minimum, 1878, August 24 ± 10. 
Maximum, 1879, March 24 zb 10. 
Combination of the Results at San Francisco and Pulpit 
Harbor. 
In combining the results I give the two stations the same 
weight. The great source of error at both stations was varia¬ 
tions in the altitude of the tide-staff zero, the amount of 
17—Bull. Phil. Soc., Wash., Vol. 13. 
