The construction of the wonderful canon of logarithms

Introduction.
xv
in the way of systematising and developing the sciences
of arithmetic and algebra, probably some years before
the publication of A plaine discovery,' appears in the
'
manuscript published in 1839 under the title De Arte
'
Logistica.' From this work it appears that his investigations
in equations had led him to a consideration of
imaginary roots, a subject he refers to as a great algebraic
secret. He had also discovered a general method for the
extraction of roots of all degrees.
The decimal system of numeration and notation had
been introduced into Europe in the tenth century. To
complete the system, it still remained to extend the
notation to fractions. This was proposed, though in a
cumbrous form, by Simon Stevin in 1585, but Napier
was the first to use the present notation.*
Towards the end of the sixteenth century, however,
the further progress of science was greatly impeded by
the continually increasing complexity and labour of
numerical calculation. In consequence of this, Napier
seems to have laid aside his work on Arithmetic and
Algebra before its completion, and deliberately set
himself to devise some means of lessening this labour.
By 1594 he must have made considerable progress in
his undertaking, as in that year, Kepler tells us, Tycho
Brahe was led by a Scotch correspondent to entertain
hopes of the publication of the Canon or Table of
Logarithms. Tycho's informant is not named, but is
* See note, p. 88.
c 2 generally