The coloring is beautiful in this view of the Twin Lights on Thacher Island. The two men on the rocks appear to be looking not at the island, but at something to the left of it. We can only imagine what the man in the straw boater hat was pointing at.
The postcard provides few clues to help me date the image. No publisher is named and the card is unused and undated. The card itself was published sometime after 1906, because it has a divided back, which postal regulations did not allow until early 1907.
I looked at the image for clues. Straw boater hats were most popular from the late 1890s to around 1920. But they remained fairly common into the 1930s and, of course, can still be found today. So that doesn’t tell us much.
The best clue I can find as to the date of the image is in something missing from Thacher Island. I do not see the chimney of the whistle house. Look at this postcard from around 1922 and you can see the whistle house and its chimney to the left. Here is another view, from the shore looking out at the island, where you can clearly see the chimney between the two lighthouses.
The whistle house was built from 1886-1887. The chimney, however, was not constructed until 1903, according to the document filed to nominate the Twin Lights as a national historic landmark.
That would suggest that this image is from before 1903, even if the postcard was printed some years later. That’s the best evidence I have to go on. If anyone has any other ideas about this card, please let me know.
I think you are correct on the date where his outstretched arm is there was a radio compass station and naval barracks building there about1915 used to track German subs in WWI.