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Briggs logarithms.

Achievement
Briggs is especially known for his publication of tables
of logarithms to the base 10, first Logarithmorum chilias prima, 1617,
and later Arithmetica logarithmetica, 1624.
He also composed a work on trigonometry (basically tables,
both of the functions and of the logs of sines and tangents) that was
left unfinished at his death; Gellibrand completed and published it. And
he left quite a few mathematical manuscripts that remained unpublished.

 Biography

 Father
 Occupation: Unknown
 Thomas Smith, writing early in the 18th century, said
that Briggs' parents were "humble of class and rather slender of
means." Humble of class could mean too many things to guess, but
I take the slender means to state unmistakably that they were poor.
Smith indicates that Briggs could not have attended Cambridge without
financial assistance from his college.

 Education
 Schooling: Cambridge, M.A.
 Local grammar school.
 St. John's College, Cambridge, 157785; B.A., 1581;
M.A., 1585.
 Religion
 Affiliation: Calvinist
 He is described in one fairly contemporary source as
a severe Presbyterian, and he was active in the Puritan cause while
he was at Cambridge.

 Scientific Disciplines
 Primary: Mathematics
 Subordinate: Astronomy, Navigation, Geography
 Briggs is especially known for his publication of tables
of logarithms to the base 10, first Logarithmorum chilias prima, 1617,
and later Arithmetica logarithmetica, 1624.
 He also composed a work on trigonometry (basically
tables, both of the functions and of the logs of sines and tangents)
that was left unfinished at his death; Gellibrand completed and published
it. And he left quite a few mathematical manuscripts that remained unpublished.
 Briggs also devoted some attention to astronomy and
saw logarithms initially primarily as a device to aid in astronomical
calculations.
 He published Tables for the Improvement of Navigation,
1610, and Northwest Passage to the South Sea, 1622.
 Briggs was consulted by the Virginia Company about
the northwest passage, and from information about tides and currents
he deduced the existence of such a passage. From the flow of rivers
in Virginia and in the Hudson Bay area, he also deduced the existence
of the midcontinental range of mountains. He produced a map of North
America that Purchas published.
 Means of Support
 Primary: Academia
 Fellow of St. John's College, 1589. I find no information
about what he did between 1585 (his M.A.) and 1589.
 Appointed Dr. Linacre's Reader of the Physic Lecture,
15926. (I am pretty sure that this was internal to St. John's College.)
 Professor of Geometry, Gresham College, 15961620.
Briggs was the first Gresham Professor of Geometry.
 Savilian Professor of Geometry, Oxford, 162030. Also
Fellow of Merton.
 Patronage
 Types: Gentry, Court Official
 He was appointed Professor of Geometry at Oxford at
Henry Saville's invitation. He held the position in the last decade
of his life. [Source on patronage: J. Ward, The Lifes of the Professors
of Gresham College, pp. 1246, LF795.G8A2]
 In his early life of Briggs, Dr. Smith says that he
condemned riches and preferred a life of retirement to one of splendor.
 Nevertheless he did dedicate Arithmetica logarithmetica
to Prince Charles.
 Technological Involvement
 Types: Applied Mathematics, Navigation, Cartography,
Instruments
 See above. Virtually the whole of his work in mathematics
was devoted to making computation more easy.
 Briggs' first publication, Concerning the Construction,
Description and Use of Two Instruments Invented by Mr. Gilbert, was
devoted to the concept of determining latitude from magnetic declination.
The work included tables for this purpose. He also constructed several
tables of astronomical phenemena useful to navigation, which were published
in Wright's book.
 See above about the map of North America.
 Note also that he considered (I do not know how deeply
or how long) the problem of constructing a canal from the Isis to the
Avon. Without more information I am unwilling to list this.
 Scientific Societies
 Memberships: None
 Informal Connections: Friendship with Sir Henry Bourchier,
Dr. Ussher and Henry Gellibrand. Two of his (apparently many) letters
to Ussher, a correspondence about astronomy and chronology, survive.
 He journeyed to Scotland twice to meet and discuss
with Napier.
 He exchanged a couple of letters with Longomontanus.

Briggs was the man most responsible for scientists' acceptance of logarithms.
He was educated at Cambridge University. In 1592 he became
reader of the Linacre lecture and in 1596 became the first professor of
geometry at Gresham College, London. In 1619 he was appointed professor
of geometry at Oxford.
Briggs published works on navigation, astronomy, and mathematics.
In his lectures at Gresham he proposed that Napier's
logarithms would be more useful if they were to base 10, so called 'common'
logarithms. After travelling to Edinburgh on two occasions to visit Napier,
he constructed a table of logarithms (1617) that was used until the 19th
century.
In 1619 he was appointed Savilian professor of geometry
at Oxford.
Briggs' Arithmetica Logarithmica (1624) contained
the logarithms of 30000 natural numbers computed to 14 places. In 1631
he published, at Gouda in the Netherlands, tables of sinec functions to
15 places and tangent and secant functions to 10 places. In 1633 these
were also published in London under the title Trigonometrica Britannica
.
Chronology
 1617
 Henry Briggs discusses decimal logarithms in Logarithmorum
Chilias Prima used Napier's ideas to produce logarithm tables which
all mathematicians use today.

 1561  1630
 English Invented common, or Briggsian, logarithms,
and was responsible for widespread adoption of logs in Europe.
 1617
 struck a deal w/Napier and published.(ref. Linacre
Lecture, Gresham College, Savilian Prof. of Geom @ Oxford)
 1619
 Henry Briggs becomes Savilian Professor of Astronomy
at Oxford. Sir
William Harvey (15781657), in lectures at St. Barthlolmew's Hospital,
outlines his discovery of the circulation of the blood. Henry Briggs
and John Napier use the decimal notation for fractions.
 1622
 book on travels to America.
 1624:
 Arithmetica Logarithmica, logs to 14 places,
since functions to 15 places, tangent and secant functions to 10 places.
 1632:
 Trigonometrica EB, more of the same.

Bibliography
Briggs published works on navigation, astronomy, and mathematics.
In his lectures at Gresham he proposed that Napier's
logarithms would be more useful if they were to base 10, so called 'common'
logarithms. After travelling to Edinburgh on two occasions to visit Napier,
he constructed a table of logarithms (1617) that was used until the 20th
century.
Briggs' Arithmetica Logarithmica (1624)
In 1631 he published, at Gouda in the Netherlands, tables of sin functions
to 15 places and tan and sec functions to 10 places.
In 1633 these were also published in London under the title Trigonometrica
Britannica .


