Rules were raised strips that were used to print lines and borders. (Rummonds, Nineteenth- Century Printing Practices, 1:249–250; 2:1032.)
Rummonds, Richard-Gabriel. Nineteenth-Century Printing Practices and the Iron Handpress. 2 vols. New Castle, DE: Oak Knoll Press; London: British Library, 2004.
A chase is a “rectangular cast or wrought iron frame” into which pages of type (known as a form) are locked in preparation for printing. An imposing stone is a “perfectly flat, smooth surface, usually polished stone or cast iron, upon which the compositor imposes and corrects his forms.” (“Chase,” “Form,” and “Imposing Stone,” in Rummonds, Nineteenth-Century Printing Practices, 2:976, 990, 998.)
Rummonds, Richard-Gabriel. Nineteenth-Century Printing Practices and the Iron Handpress. 2 vols. New Castle, DE: Oak Knoll Press; London: British Library, 2004.