[45]H. Hankel, Geschichte der Mathematik in Alterthum und Mittelalter, Leipzig, 1874, pp. 369, 370.
[46]M. Cantor, Vorlesungen über Geschichte der Mathematik, II, 1900, pp. 640, 641.
[47]This matter has been discussed in a paper by F. Cajori, “A History of the Arithmetical Methods of Approximation, etc., Colorado College Publication, General Series No. 51, 1910, pp. 182-84. Later this subject was again treated by G. Eneström in Bibliotheca mathematica, 3. Folge, Vol. XI, 1911, pp. 234, 235.
[48]See F. Cajori, op. cit., p. 193.
[49]See William Oughtred’s Key of the Mathematicks, London, 1694, pp. 173-75, tract, “Of the Resolution of the Affected Equations,” or any edition of the Clavis after the first.
[50]A. De Morgan, op. cit., p. 451; 2d ed., Vol. II, p. 303.
[51]See F. Cajori, History of the Logarithmic Slide Rule, New York, 1909, pp. 7-14, Addenda, p. ii.
[52]Rigaud, op. cit., Vol. I, p. 12.
[53]The New Artificial Gauging Line or Rod: together with rules concerning the use thereof: Invented and written by William Oughtred, London, 1633.
[54]W. Oughtred, Apologeticall Epistle, p. 13.