Two years after Dürer had published his observations on this subject Henricus Loriti Glareanus (1488-1551) issued a small treatise on geography,[196] devoting his Chapter XIX bearing title ‘De inducendo papyro in globo’ to globe-gore construction. He proposed the employment of twelve gores or biangles (Fig. 134) so arranged for printing that the shorter diameter of each should represent 30 degrees of longitude, the sum therefore representing 360 degrees or the equatorial circumference of the globe they were intended to cover; the longer diameter of each gore representing the semicircumference of the globe and extending from pole to pole, that is, a meridian. We do not know that his formula for gore construction was closely followed by any globe maker of the period, nor does Glareanus himself appear to have attempted a practical application of his method, at least we have no evidence that he ever actually attempted to construct a globe. He, however, had made an important contribution toward the solution of the problem of how best to multiply these instruments which were increasingly recognized as of great value in geographical and astronomical studies. The general method of gore map making rapidly found favor despite such practical difficulties, for example, as arose from the peculiarity inseparable from the quality inherent in any and all paper, that is, its irregular expansion when moistened. This difficulty the globe makers, of course, were continually seeking to overcome or reduce to a minimum, as the years passed, through a careful selection of paper to be used, through a more skilful manipulation of the paper made moist by the application of the paste or glue employed in attaching the map to the surface of the sphere,[197] and through a more careful working out of the mathematical problem having to do with the proper proportions of each of the gores. Dürer had proposed the employment of sixteen segments, Waldseemüller, Schöner, Boulengier, and Glareanus had thought twelve a more suitable number. As the years passed we find a preference manifesting itself now for twelve, now for sixteen, now for eighteen, twenty-four, or thirty-six with a more common preference for the smaller number. The several biangles for the maps alluded to above were fashioned to extend from pole to pole in what we may call the equatorial system; Mercator, as has been noted, introduced the novel idea of truncating his gores twenty degrees from each pole, preparing as a covering for the remaining polar space a circular disc, having the required diameter of forty degrees.[198] This plan he proposed for the practical reason that a paper covering for a sphere so constructed could be applied with greater ease and with greater accuracy than one consisting of complete biangular figures, remembering the tendency of the paper to expand and the difficulty in avoiding folds.