01 redrawn from a medieval miniature - To the left - a lectern; To the right the reader at a lectern with table, adjusted with a crank mechanism to bring closer to the eyes.

02. from Defectus. Negligentie et Defectus in Missa Contingentes , Erfurt 1494.

03. Albrecht Durer, engraving, St.Jerome in his Study , dated 1514, and measuring 18 x 24 cms.

04 from Agostino Ramelli, Le Diverse et Artificiose Machine ( The Various and Ingenious Machines) , the Parisian edition of 1588.

05. The Author caught in the act of contemplation, from Bernardo Bellinzoni's Rime , Milan 1493.

06 N.Grollier, Receuil D"Ouvrages curieux de Mathematique et de Mecanique , Forey, Lyons, 1719