105. lignes géométriques The Paris line was approximately 1/12 inch; (it was 1/12 pouce which in turn was 1/12 pre-revolutionary pied (pié) . The modern standardized conversion is 1 ligne (line) = 2.2559 mm. Fournier’s pouce, which contained 12 of his lignes or 72 points, was apparently smaller that the standard pouce of the time since the height of text to be measured was 40 Fournier lignes or 37 standard lignes .

Diderot does not really make clear what was to be measured. In fact it was a height, that is to say it was a distance to be measured parallel to the vertical edge of the page, from the bottom of a line of text downward. The required height of text to measure was 40 x 6 = 240 of Fournier’s points. Since his table gives his body sizes in points it is easy to calculate that this distance should contain, for example 20 Cicéros, that is to say, 20 lines of text set in the Cicéro face .

The operation is the inverse of the modern method of estimating the body height of a given type by measuring the vertical height of 20 lines of the type rather than measuring a fixed distance and counting the number of lines it contains.