My guess is that fan is post WW II.

I sincerely doubt that a fan would have been installed in the house in 1903. That was really the dawn of electricity, and depending on where your house is located, it might not have had electricity until as late as the 1930s, when the Rural Electrification Association got electricity to a lot of rural areas.

Electric probably wasn't even in that house in 1903 so the fan would be a later instal and not be of any use getting the date of the house.

What does the brass plate on the motor say? That may have some info on manufacturer, serial number, patent dates.
Casey

Cute house! Hope you install a modern attic fan, they are great!
kathy

"brass plate"

The use of actual brass (most are aluminum now) would help place it generally to pre-WWII.