Jean-Charles, chevalier de
Borda (May 4, 1733 – February 19, 1799) was a French mathematician, physicist, political scientist, and sailor.
Life History
Born in
the city of Dax, in 1756 Borda wrote Mémoire sur le mouvement
des projectiles, a product of his work as a military engineer. For that, he was
elected to the
French Academy
of Sciences in 1764.
Borda was
a mariner and a scientist, spending time in the Caribbean testing out advances in chronometers.
Between 1777 and 1778, he participated in the
American Revolutionary War. In
1781, he was put in charge of several vessels in the
French Navy. In 1782, he was captured by the
English, and was returned to France shortly after. He returned as
an engineer in the French Navy, making improvements to waterwheels
and pumps. He was appointed as France's Inspector of Naval
Shipbuilding in 1784, and with the assistance of the naval
architect
Jacques-Noël
Sané in 1786 introduced a massive construction programme to
revitalise the French navy based on the standard designs of
Sané.
In 1770, Borda formulated a ranked preferential
voting system that is referred to as the
Borda count. The
French Academy of Sciences used
Borda's method to elect its members for about two decades until it
was quashed by
Napoleon Bonaparte
who insisted that his own method be used after he became president
of the Académie in 1801. The Borda count is in use today in some
academic institutions, competitions and several political
jurisdictions. The Borda count has also served as a basis for other
methods such as the
Quota Borda
system and
Nanson's
method.
Another of his contributions is his construction of the standard
metre, basis of the
metric system to correspond to the
measurements of
Delambre.
Reflecting circle, on display at
Toulon naval museum
As an
instrument maker, he improved the reflecting circle
(invented by Tobias Mayer) and the
repeating circle (invented by his
assistant, Etienne
Lenoir), the latter used to measure the meridian arc from
Dunkirk to Barcelona by Delambre and Méchain.
Tables of Logarithms
With the advent of the metric system after the French Revolution it
was decided that the quarter circle should be divided into 100
degrees instead of 90 degrees, and the degree into 100 seconds
instead of 60 seconds. This required the calculation of
trigonometric tables and logarithms corresponding to the new size
of the degree and instruments for measuring angles in the new
system.
Borda constructed instruments for measuring angles in the new units
(the instrument could no longer be called a "sextant") which was
later used in the measurement of the meridian between Dunkirk and
Barcelona by Delambre to determine the length of the
metre. The tables of logarithms of sines, secants, and
tangents were also required for the purposes of navigation. Borda
was an enthusiast for the metric system and constructed tables of
these logarithms starting in 1792 but their publication was delayed
until after his death and only published in the Year 9 (1801) as
Tables of Logarithms of sines, secants, and tangents,
co-secants, co-sines, and co-tangents for the Quarter of the Circle
divided into 100 degrees, the degree into 100 minutes, and the
minute into 100 seconds to ten decimals, and including his
tables of logarithms to 7 decimals from 10,000 to 100,000 with
tables for obtaining results to 10 decimals.
The division of the degree into hundredths was accompanied by the
division of the day into 10 hours of 100 minutes and maps were
required to show the new degrees of latitude and longitude. The
Republican Calendar was
abolished by Napoleon in 1806, and presumably with it the 400
degree circle.
Honours
See also
References