"brain boxes".

Before the 1950s, the phrase "think tank" did not refer to organizations. From its first appearances in the 1890s up to the 1950s, the phrase was most commonly used in American English to colloquially refer to the braincase or especially in a pejorative context to the human brain itself when commenting on an individual's failings (in the sense that something was wrong with that person's "think tank"). Around