- Cajori, Florian. 1928. *A History of Mathematical Notations* (London: The Open Court Publ. <https://archive.org/details/historyofmathema031756mbp>
has the following remarks in paragraph 95, p. 63:
Relative size of numerals in tables.-- André says on this point: "In certain numerical tables, as those of
Schrön, all numerals are of the same height. In certain other tables, as those of Lalande, of Callet, of Houël, of Dupuis, they have unequal heights: the 7 and 9 are prolonged downward; 3, 4, 5, 6 and 8 extend upward; while 1 and 2 do not reach above nor below the central body of the writing.... The unequal numerals, by their very inequality, render the long train of numerals easier to read; numerals of uniform height are less legible." (D. André, Des notations mathématiques (Paris, 1909), p .9).