An account of the contents of the manuscripts of John Napier in the possession of the family which survived a disastrous fire at the end of the 18th century was given by Mark Napier in the appendix to his Memoirs of John Napier, and the manuscripts themselves were edited in their entirety by him in 1839 under the title De Arte Logistica Joannis Naperi Merchistonii Baronis Libri qui supersunt. Impressum Edinburgi M.DCCC.XXX.IX., as one of the publications of the Bannatyne club. The Arithmetica con sists of three books, entitled : De Computationibus Quantita tum omnibus Logisticae speciebus communium ; De Logistica Arithmetica; (3) De Logistica Geometrica. At the end of this book occurs the note—"I could find no more of this geometricall pairt among all his fragments." The Algebra Joannis Naperi Merchistonii Baronis consists of two books: (I) "De nominata Algebrae parte; (2) De positiva sive cossica Algebrae parte," and concludes with the words, "There is no more of his algebra orderlie sett down." Besides the logarithms and the calculating rods or bones, Napier's name is attached to certain rules and formulae in spheri cal trigonometry. To him also seems to be due the first use of the decimal point in arithmetic. Decimal fractions were first intro duced by Stevinus in his tract La Disme, published in 1585, but he used cumbrous exponents (numbers enclosed in circles) to dis tinguish the different denominations, primes, seconds, thirds, etc.
In the Rabdologia Napier gives an "Admonitio pro Decimali Arith metica," in which he commends the fractions of Stevinus and gives an example of their use, the division of 861094 by 432. The quotient is written 1993,273 in the work and 1993,2'7"3' in the text. The decimal point is, however, used systematically in the Constructio (1619), there being perhaps two hundred decimal points altogether in the book.
Napier was in possession of all the conventions and attributes that enable the decimal point to complete so symmetrically our system of notation, viz. (I) he saw that a point or separatrix was quite enough to separate integers from decimals, and that no signs to indicate primes, seconds, etc., were required; (2) he used ciphers after the decimal point and preceding the first significant figure ; and (3) he had no objection to a decimal standing by itself without any integer. Napier thus had complete command over decimal fractions and the use of the decimal point.
The bibliography of Napier's work attached to W. R. Macdonald's translation of the Canonis Constructio (1889) is complete and valuable. Napier's three mathematical works are reprinted by N. L. W. A. Gravelaar in Verhandelingen der Kon. Akad. van Wet to Amsterdam (1899).