Steve Reeves worked his calves doing Barbell Hack Squats going up on his toes, and putting the bar down between each rep, as Georg Hackenschmidt did. Hackenschmidt popularized the Barbell Hack Squat, and it was named for him, as people started calling it "Hack's Squat," though Hackenschmidt himself said the name "Hack" came from the German word for heel, as you need to lift your heels.
Steve Reeves designed a Barbell Hack Squat Machine (Not to be confused with modern Hack Squat Machine) when he was training at York, with Jon Grimek, for the Mr. Universe. The machinists there built it for him, and he used it to good effect.