2i6 
Gassendi, indeed, in the Life of 
Tycho Brahe, mentions a compendious 
method of calculation in trigonometry, 
as discovered by hima, in which addition 
and subtraction was used, instead of mul- 
tiplication and .division. And in one 
place he adds this remark : Quod wt fieri 
posset, docutt postmodum suo Logarithmo- 
rum Canone Neperus.* - 
Bat that Nepers’ discovery was alto- 
gether different from what was spoken of 
by Gassendi, may appear by consulting 
the authors, by which the artitice itself, 
then used for that purpose, is particularly 
explained.f This invention was no sooner 
known, than it gained the applause of 
all the eminent mathematicians of that 
age, who found it fo answer what the 
noble author had said of it, in his dedi- 
eation to Prince Charles—that “ admini- 
culo plures guestiones mathematice untus 
hore spatio, quam pristina et communiter 
recepla forma sinuum, tangentium, et 
secantium, vel integra die absolvantur.” 
But no one more extolled it than Mr. 
Briggs, who spaaks thus of it in the letter 
above-mentioned. ‘* Naper, Lord of 
Markiston, hath set. my head and 
hands to work with his new and admira- 
ble logarithms,.—I hope to see him this 
summer, if it please God; for I never 
saw a book which pleased me better, and 
made me more wonder.{ And he kept his 
resolution; for when summer came on, 
in the year 1616, he took a journey into 
Scotland, to converse with him upon 
that subject, and the summer following 
made him a second visit. This year the 
Baron published his Rabdologia, in the 
dedication of which to the Lord Chan- 
cellor Seton, he mentions another. spe- 
cies of logarithms, different from what 
he had published in 1614, and which he 
had invented since that time. _ His words 
are these:—‘ Logarithmorum speciem 
aliammulto prestantiorem nunc etiaminve- 
nimus, et creand: methodum una cum eorum 
usu,, si Deus longiorem vita et. valetudi-° 
nis concesserit, € vulgare statuimus, ip- 
sam autem novi canonis supputationem ob 
infirmam corporis nostri valetudinem viris 
in hoc studii genere versatis relinguimus ; 
amprimis vero D. Henrico Briggs, Londini. 
puolico geometrie professori, et amico 
mihi charissimo.§, It seems, from this 
passage, as if the Baron, being then sen- 
* jychBrabes Vit. a Pet. Gassend. p. 109, 
165, ed. 1655, 4to. ‘ ee 
. + Vid. Clavium de Astrolab, Lib. i. Lem. 
$33 Pitisci Trigonomet. Lib. 7. Initium, &c, _. 
ft Usher's Letters, p. 36. 
§ Ediaburgi, 1617, 8v0. 
Memotrs of Henry Briggs, the Mathematician. [Oct. 1, 
sible of his declining health, was desirous, 
by this public notice of his new method of 
logarithms, and his expectations from 
Mr. Briggs, to eugage him move firmly 
in the prosecution of that useful, bat 
very laborious, work, here mentioned. 
Soon after the publication of the “ Canon 
Mivificus Logarithmorum,” it was trans- 
lated imto English by Mr. Edw. Wright, 
and sent to the auther into Scotland for 
his perusal, who approved of it very well > 
but Mr. Wright dymg before the book 
returned from Scotland, the care of the 
impression was, both by him and the Ba- 
ron, committed to Mr. Briggs, who pub- 
lished it in the year 1616, containing 
some account of its excellent uses ; and 
a description of the instrumental table, 
to find the part proportional, placed at 
the end. But in the year 1617, after 
the discovery of the second sort of loga- 
rithms, Mr. Briggs, for the sake of his | 
friends and hearers at Gresham Cols 
Jege, printed his Logarithmorum Chilias 
prima, which was of that kind, as inti- 
mated in the preface, where he says, 
Quod auten hi logarithini deversi sint ab 
228, guos charissimus inventor, memoria sem= 
per colenda, in suo edidit Canone Mirifico, 
sperundum ejus librum posthumuin, abun- 
de nobis propediem satisfacturum; and 
this Ciilias Prima is what Sir Henry - 
Bourchier refers to in the following pas- 
sage of aletter, written by him to Dr. 
Usher: “Our kind friend, Mr. Briggs, hath 
lately published a supplement to the most 
excellent Table of Logarithms, which, 
I presume, -he has sent you.”* This letter 
is dated the 6th of December, 1617, and 
that the Chilias Prima was printed the 
same year, appears by the title page. 
But as the Baron did not die till the Sd __ 
of April, 1618,¢ and as his death is inti- 
mated by Mr. Briggs, in the words of 
his preface just before cited, the book, I 
presume, was not published before the 
Baron’s decease, when it came out with 
that- preface before it, in which men- 
tion is made of a posthumous work, writ- 
ten by the Baron, that might shortly be 
expected, and was afterwards published 
by his son, in the year 1619. We find 
by the passage etn & above from 
the Baron’s dedication of his Rabdolegia, 
that what he purposed to do himself, in 
relation to the second species of loga- — 
rithms, was only to give an account how 
they were made, and explain the use of 
them; and to leave the labour of their 
* Usher's Letters, p- 62. 
+ Mac Kenzie ubi supra, p. 513. X 
calculation 
