Distance to celestial objects chart


This beautiful old chart, headed "Unbelievable Time Required to Cover Immense Distances of Space", displays the time it would take to get to various "nearby" celestial objects, using an unspecified propulsion system. Does anyone know what that system was, or where the chart comes from?

Unbelievable Time Required to Cover Immense Distances of Space (via A Whole Lotta Nothing)