B chapter.indd - Charles Babbage Institute - University of Minnesota

B 250
Briggs, Henry (1561–1631)
Arithmetica logarithmica sive logarithmorum chiliades
triginta, pro numeris naturali serie crescentibus ab
unitate ad 20,000: et a 90,000 ad 100,000.
Year: 1624
Place: London
Publisher: W. Jones
Edition: 1st
Language: Latin
Binding: contemporary reverse leather; rebacked; brown
leather label
Pagination: pp. [8], 88, [300]
Collation: a–m 4 A–Q 6 R 4 4H 8 4I–4O 6 * 6
Size: 324x199 mm
Reference: Pogg Vol. I, p. 298; DSB II, p. 462; Hend BTM,
#18, p. 40; Horb CC, #38, pp. 33; Car PMM, #116, pp.
69–70
Henry Briggs graduated from Oxford with an M.A. in
1585 and remained there as a junior academic. He was
elected as a Fellow of St. John’s College in 1589. In 1596,
he was invited to be the founding professor of geometry
at the newly created Gresham College in London, where
he worked lecturing and creating navigational tables.
Shortly after Napier published his Mirifici logarithmorum
canonis descriptio in 1614, Briggs obtained a copy
and immediately recognized their value for navigation
and other computations. He began to teach them to his
students and soon saw that they would be easier to use if
the base was changed to 10. Briggs visited with Napier
Erwin Tomash Library
Briggs, Henry Briggs, Henry
B 250
Briggs’ logarithms, B 250
in the summer of 1615 and again in 1616, and after the
two men had agreed on the proposed changes, Briggs
began calculating the new base 10 logarithms. Napier
took no part in this work as he was not well and died the
following year. In 1617, Briggs supervised the printing
of a translation of Napier’s work produced by Edward
Wright, who had also died shortly after finishing it. In a
preface to this translation, he justifies the change to base
10 and includes a small table of logarithms of numbers
from 1 to 1000 (the first chiliad).
This volume contains logarithms for numbers from 1 to
20,000 and from 90,000 to 100,000. It took until 1624
to produce the table in this volume. Briggs did not start
calculating logarithms in succession, but he used a number
of critical logarithms (see illustrations) for 0, 10 1/2 , 10 3/4 ,
etc. to calculate the others. Briggs wrote a preface in
which he explained how to use logarithms and gave a
plan for calculating the missing 70,000 numbers—even
offering to supply special paper divided into columns
for anyone willing to help. He provided the difference
between each adjacent value (see illustrations) and a
method of calculating logarithms by interpolation from
differences. The missing seventy chiliads were included
in the second edition of this work published by Adrian
Vlacq in 1628, although Briggs had, by this time, nearly
completed the calculations himself. It was in the preface
to this work that Briggs coined the terms characteristic
and mantissa for the two portions (on either side of the
decimal point) of a logarithmic number.
Some copies of this work have an additional six pages
containing the logarithms for 100,001 to 101,000 and a
table of square roots from 1 to 200. This volume does
not contain these extra pages, but they are to be found
in another issue in this collection (see entry for Briggs,
Henry; Arithmetica Logarithmica, 1624–another issue).
These logarithms, together with those of Adriaan Vlacq
mentioned above, form the basis from which almost all
other logarithm tables were produced. At the end of the
eighteenth century, the French produced the Tables du
Cadastre, which are only available in manuscript form
(see entry for Prony). Towards the end of the nineteenth
century, Edward Sang (1805–1890) published a seven-
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