THE INVENTION
Throughout the Renaissance, many attempts were
made to develop a universal instrument that could
be used to perform arithmetical calculation and
geometric operations easily. This need was felt
especially in the military field, where the technology
of firearms called for increasingly precise mathematical
knowledge. To satisfy these requisites, the first
proportional compasses were developed in the
second half of the sixteenth century, among them
some singular instruments known as the "radio
latino" and the "proteo militare".
The geometric and military compass of Galileo
belonged to this class of instruments. Invented
in Padua in 1597, the instrument is also linked
to Galileo's activity in the Accademia Delia,
founded in Padua to provide mathematical instruction
for young noblemen training for a military career.
With the seven proportional lines traced on the
legs of the compass and the four scales marked
on the quadrant, it was possible to perform with
the greatest of ease all sorts of arithmetical
and geometric calculations, ranging from calculating
interest to extracting square and cube roots,
from drawing polygons to calculating areas and
volumes, from measuring gauges to surveying a
territory. Between 1598 and 1604, Galileo instructed
several European sovereigns on the use of his
compass, among them Prince John Frederick of
Alsace, Archduke Ferdinand of Austria, the Landgrave
Philippe of Hesse and the Duke of Mantua.
THE
SUCCESS
OF
THE
INSTRUMENT
The
success
of
the
instrument
encouraged
Galileo
to divulge his invention still further. In 1606
he published 60 copies of Le operazioni del compasso
geometrico e militare, each of which he sold
privately along with one of the instruments.
The production of compasses, from which Galileo
earned a substantial profit, was entrusted to
an instrument-maker whom the scientist housed
for some years in his own home. The publication
of the treatise immediately aroused great interest,
so intense as to provoke bitter arguments in
the academic world over the authorship of the
invention. Already in 1607 Baldassarre Capra,
one of Galileo's pupils, tried to claim credit
for the invention of the instrument among erudite
circles by publishing a treatise in Latin on
its operations. Other adversaries of Galileo
claimed that the instrument had been invented
first by the Dutch mathematician Michel Coignet.
Many variations in the instrument were made and,
with the addition of new proportional lines,
its fields of application were later extended.
Specific treatises were written by Michel Coignet,
who called it "compasso pantometro",
by Muzio Oddi who called it "compasso polimetro",
by Ottavio Revesi Bruti who, adding proportional
lines for architectural drawing, called it "archisesto",
by Girard Desargues and other French mathematicians
who, adding proportional lines for perspective
drawing, called it the "optical or perspective
compass". Numerous variations were developed
throughout the seventeenth and eighteenth centuries,
while during the course of the nineteenth, the
proportional compass was gradually replaced by
the dissemination of highly refined slide rules
which survived in the technical studios of engineers,
architects and geometers up until the very recent
advent of the computer. |
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