8/12/2019 Frisius, Regnier Gemma
2/3
or%hane& as a youth) *e began his stu&ies in Groningen
atten&ing the ni ersity of 'ou ain where he
recei e& his licentiate in 15#8 an& a me&ical
&egree in 1536) In 1541 he was a%%ointe& %rofessor of
me&icine an& mathematics at 'ou ain where he earne&
a re%utation as the lea&ing theoretical
mathematician in the 'ow 7ountries) Gemma Frisius use& his
mathematical abilities in the areas ofgeogra%hy astronomy an&
ma% ma,ing) *e %ro&uce& a worl& ma% with lines an&
longitu&e an&
so%histicate& ariations on the astrolabe such as the
astronomical ring)9 .he instrument is sus%en&e&
by a %iece attache& to a s%lit ring allowing the outer
meri&ian ring to sli&e an& be set for a gi en
latitu&e using two engra e& :ua&rants one for
northern one for southern latitu&es) .he self;orientating
&e ice a oi&s the use of a magnetic com%ass)
Gemma Frisius< De Principiis Astronomiae & Cosmographiae
( =n the >rinci%les of ?stronomy an&
7artogra%hy 9 1530$ was translate& into se eral languages
an& re%rinte& many times) In his Libellus de
locurum (1533$ he &escribe& the theory of trigonometric
sur eying) .he wor, is the first ,nown source
of using the metho& of triangulation as a means of
accurately ma%%ing areas) .riangulation uses the
fact that the &istance between two %oints an& the
bearings of a thir& %oint from the en&s of this base
line %ro i&es the location of the thir& %oint) .his
metho& %ro i&e& an accurate means of sur eying
using relati ely few obser ations)
Gemma Frisius wrote Tractatus de Ammulo Astronomicae (1534 ) in
which he a%%lie& trigonometric
metho&s to astronomical %roblems) *e ma&e numerous
astronomical obser ations %articularly
recor&ing the motions of comets) Gemma Frisius<
Arithmeticae Practicae Methodus Facilis (1540$
went through fifty;nine e&itions ma,ing it one of the most
successful mathematical te@tboo,s of the
%erio&) *e was a %ioneer in the use of the %inhole camera
which he use& to stu&y the solar ecli%se of
1544) 'ight entering his close& &ar,ene& laboratory
through a small hole in the &oor cast an image onto
a screen or wall o%%osite the hole) ohannes Ae%ler first
use& the term camera obscura9 from camera
8/12/2019 Frisius, Regnier Gemma
3/3
'atin for room9 an& obscura, 'atin for &ar,9 to
&escribe such instruments in the early 1B th century)
.he camera obscura allowe& astronomers to ma,e solar obser
ations without &amaging their eyes)
Quotation of the Day: C it is with the hel% of these cloc,s
an& the following metho&s thatlongitu&e is foun&) C
obser e e@actly the time at the %lace from which we are ma,ing our
/ourney) C
hen we ha e com%lete& a /ourney C wait until the han& of
the cloc, e@actly touches the %oint of an
hour an& at the same moment by means of an astrolabe C
fin& out the time of the %lace we now fin&
oursel es) C In this way I woul& be able to fin& the
longitu&e of %laces e en if I was &ragge& off
unawares across a thousan& miles) C it must be a ery finely
ma&e cloc, which &oes not ary with
change of air)9 ! Regnier Gemma Frisius
