Hiram Maxim (1840-1916), from
a Vanity Fair cartoon. Is he
listening for echoes?

Hahn repeated Spallanzani's and Jurine's experiments (apparently unaware of the work that had been done over 100 years before). He covered the wings of bats with vaseline. The bats flitted about in the dark just as skillfully as before. The bats definitely didn't use the sense of touch to detect obstacles. But still, the scientific community didn't seem to notice:

Four years later in 1912, the engineer Hiram Maxim almost stumbled across the truth about how bats fly in the dark. It was very soon after the Titanic disaster. Maxim noted that if the Titanic crew had been as clever as bats at detecting obstacles without vision, then they might have detected the iceberg sooner and avoided the famous collision.

Maxim was inspired by bats, and thought they must have the answer...