Palomar telescope

From Popular Science magazine, December 1938 http://blog.modernmechanix.com/model-shows-200-inch-telescope/ .

Thought waves

Image: Acme news photo.

X-raying of fruit

Images: from brochure distributed at 1939 Golden Gate International Exposition.

“…in the past it has been impossible to detect certain kinds of imperfection by external appearance alone. Frost damage and granulations in oranges…leave no indications on the surface…”

“This X-ray inspection unit permits the operator to look right through the fruit instead of at its surface only.”

Excerpts from the brochure.

Mt. Wilson

Images: front and detail of 1939 postmark on postcard.

Learn about the Mt. Wilson Observatory at https://www.mtwilson.edu/about-mwo/ .

See some “found film” photos taken on Mt. Wilson in 1939: http://www.foundfilmsociety.com/dt_gallery/mt-wilson-1939/ .