Send a message to the person who requested a photo of the grave monument of Arthur Edward Hadley with the following comment:
Arthur Edward Hadley is being considered as the artist who painted a series of sketches. Ther is no attribution or signature but there is circumstantial evidence that he could be the artist. I would like to have a copy of his gravestone to go with notes being compiled about him. For your records there is an obituary ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=5321257 and there is a portrait in the National Portrait Gallery (but not available on line).