Elementary arithmetic, with brief notices of its history... by Robert Potts.

LOGARITH1IS.

before IMr. Briggs, purposely to be there when these two learned
persons should meet. Mr. Briggs appoints a certain day when to
meet at Edinburgh; but failing thereof, the Lord Napier was doubtful
he would not come. It happened one day, as John Marr and the
Lord Napier were speaking of Mr. Briggs, 'Ah, John (said Marchiston), Mr. Briggs will not now come.' At the very instant one
knocks at the gate; John Marr hasted down, and it proved Mr.
Briggs, to his great contentment. He brings Mr. Briggs up into my
lord's chamber, where almost one quarter of an hour was spent, each
beholding the other almost with admiration before one word was
spoken. At last Mr. Briggs began: 'Iy lord, I have undertaken this
long journey purposely to see your person, and to know by what
engine of wit or ingenuity you came first to. think of this most excellent help unto astronomy, viz., the logarithms; but, my lord, being by
you found out, I wonder nobody else found it out before, when now
known it is so easy.'
In the year 1617, shortly before his death, Napier published his
"Rabdologia." In the dedication is the following passage:-" 'he
difficulty and prolixity of calculation, the weariness of which is so apt
to deter from the study of mathematics, I have always, with what
powers and little genius I possess, laboured to eradicate. And with
that end in view I published of late years the Canon of Logarithms
wrought out by myself a long time ago, which, casting aside the
natural numbers, and the more difficult operations performed by them,
substituting in their place others affording the same results, by means
of easy additions, subtractions, bisections, and trisections. Of which
logarithms, indeed, I have now found out another species much
superior to the former, and intend, if God shall grant me longer life,
~and the possession of health, to make known the method of constructing as well as the manner of using them. But the actual computation
kof this new canon I have left, on account of the infirmity of my bodily
health, to those versant in those studies; and especially to that truly
most learned man, Henry Briggs, public Professor of Geometry in
London, my most beloved friead."
In the following year Briggs paid a second visit to Napier, and
after his return to London printed, in 1617, his " Chilias Prima Logarithmorum," but did not publish it till the next year after the death.of Napier, which happened on the 3rd April, 1618; for in his preface
Briggs writes, "Why these logarithms differ from those set forth by
their most illustrious inventor, of ever respectful memory, in his
' Canon Mirificus,' it is to be hoped his posthumous work will shortly
make appear."
The posthumous work was published by his son, Robert Napier, in
1619, with the title of " Mirifici Logarithmorum Canonis Constructio."
In the preface, speaking of his father, he writes:-" You have then
-(benevolent reader) the doctrine of the construction of logarithmswhich here he calls artificial numbers, for he had this treatise beside
him composed for several years before he invented the word logarithm
[Xg'ywv ftptOfloc]-most copiously unfolded, and their nature, accidences, and various adaptations to their natural numbers perspicuously
demonstrated. I have also thought good to subjoin to the construction itself a certain appendix, concerning the method of forming
another and more excellent species of logarithms, to which the
inventor alludes in his epistle prefixed to the 'Rabdologia,' and in