22 



o 



Monthly and Annual Mean Surface Water Temperatures, F 



April 1873 - February 1875, Grand Trunk Railroad l%arf ; March 1887 - February 1879, 

 Casco Bay, foot of Grand Trunk rtharf ; March 1879 - October 1888, Foot of Custom House 

 Wharf, Portland Harbor. 



Readings once per day 

 Source - USCFF 



