He put on his control machine the equation of a hyperboloid of two branches, and changed the constants gradually till the two branches came close.
"Invaders from the Infinite"
John Wood Campbell
Even the hyperboloid of two sheets, obtained by revolving the hyperbola about its major axis, was known to them, but probably not the hyperboloid of one sheet, which results from revolving a hyperbola about the other axis.
"An Elementary Course in Synthetic Projective Geometry"
Lehmer, Derrick Norman