ScientificAmerican1919-12-06.jpg Scientific American 1919-11-29ThumbnailsScientific American 1919-12-20Scientific American 1919-11-29ThumbnailsScientific American 1919-12-20Scientific American 1919-11-29ThumbnailsScientific American 1919-12-20Scientific American 1919-11-29ThumbnailsScientific American 1919-12-20

Mouth of a seven foot wind tunnel for testing airplane models.