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Although the NASM identifies this as the "Christofferson 1912 Seaplane", it looks like a 1911 Curtiss Model E to me.
Taken at San Francisco, CA. At the beach near Fort Mason. Alcatraz Island can be seen on the left of the first photo. On the tail can be seen, "Passenger Carrying & School, foot of Laguna St".
Photos from the NASM
