Map of Magnetic Variation
This map shows not only the lines of magnetic variation in North America, but also the approximate location of the north magnetic pole.
Called "The Variation of the Compass for the Year 1955," it is from Bowditch's "American Practical Navigator," H.O. Pub. No. 9, 1962, p. 163. Penobscot Bay's variation is approximately 18 degrees west.