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GRM and RRM are effects due to the application of an AF on SD

grains. They are produced whenever there is an asymmetry in the num-

ber of magnetic moments that flip in a particular sense during the AF

treatment. In other words, such remanences appear in any system

where a particular sense of flip predominates (Stephenson, 1980a,b).

RRM was explained in terms of a gyromagnetic effect associated with

the irreversible flip of SD particles during rotation of the sample in an

AF (Stephenson, 1985).

The typical SD properties of natural greigite grains may be

explained by its intrinsic magnetic and crystalline structure, with the

magnetocrystalline anisotropy dominating the magnetization process.

The theoretically estimated size range of stability for prismatic greigite

SD grains extends well beyond that of magnetite, suggesting that elon-

gated greigite crystals may be in a SD state even for very large sizes

(up to several micrometers) (Diaz Ricci and Kirschvink, 1992). More-

over, direct magnetic optical observations indicated that the single- to

two-domain transition in greigite may occur for grain sizes of

0.7–0.8 mm (Hoffmann, 1992) and that greigite usually occurs in fram-

boidal aggregates of grains individually smaller than 1 mm (i.e., Jiang

et al., 2001).

The maximum value for the M

ratio in SD grains with shape

anisotropy is 0.5. Conversely, if magnetocrystalline anisotropy con-

trols the hysteresis behavior and the <100> axis is the easy axis of

magnetization, it would be expected that M

would approach a

value of 0.832 as B

approach unity. Under the same circumstances

if <111> is the easy axis of magnetization M

is predicted to

approach 0.866 (O’Reilly, 1984; Dunlop and Özdemir, 1997).

A magnetic method for discriminating between greigite and pyrrho-

tite in paleomagnetic samples has been proposed by Torii et al. (1996),

based on the thermal demagnetization of a composite IRM and relying

upon the instability and alteration of greigite during thermal heating at

temperatures above 200



Notwithstanding its metastable properties and magnetic instability,

the importance of greigite for paleomagnetism and magnetostratigra-

phy has been particularly stressed in recent years since it has been

widely recognized as a carrier of stable chemical remanent magnetiza-

tion (CRM) in lacustrine and marine sediments, with ages ranging

from the Cretaceous to the Present (e.g., Snowball and Thomson,

1990; Snowball, 1991; Hoffmann, 1992; Krs et al., 1990, 1992;

Roberts and Turner, 1993; Hallam and Maher, 1994; Reynolds et al.,

1994; Roberts, 1995; Roberts et al., 1996; Sagnotti and Winkler,

1999), as well as in soils (Fassbinder and Stanjek, 1994).

Fe-Ni sulfides

Smythite (Fe, Ni)

, pentlandite (Fe, Ni)

, and other complex

Fe-Ni sulfides were occasionally reported in sediments (i.e., Krs et al.,

1992; Van Velzen et al., 1993) in association with pure Fe sulfides, but

their magnetic properties have not been studied in the detail so far.

Occurrences: formation, preservation, problems, and

potential for use in paleomagnetism

Troilite is common in meteorites and lunar rocks, but not on Earth.

Pyrrhotites are ordinary magnetic carriers in magmatic, hydrother-

mal, and metamorphic rocks. Pyrrhotite in metamorphic rocks has

been shown to acquire postmetamorphic partial thermomagnetic rema-

nent magnetization (pTRM) during the uplift of mountain belts and

has been used as a thermometer for postmetamorphic cooling (thermo-

paleomagnetism) and for dating and evaluation of exhumation rates

through various reversals of the Earth magnetic field (i.e., Crouzet

et al., 1999, 2001a,b).

Pyrrhotite has also been recognized as the main remanence carrier

in Shergotty-Nakhla-Cassigny type (SNC) Martian meteorites, and

inferred as a main magnetic phase in the crust of Mars with significant

implication for a proper evaluation of magnetic anomalies on such

planet (Rochette et al., 2001).

Pyrrhotite and greigite occur also as authigenic phases in geolo-

gically young or recent sediments deposited under anoxic, sulfate-

reducing conditions (Figure I32).

The presence of magnetic iron sulfides in sediments is of special

interest, since they have important implication for magnetostratigraphy

and environmental magnetism. Reduction diagenesis and authigenesis

can significantly affect the magnetic mineralogy of sediments (Karlin

and Levi, 1983; Karlin, 1990a,b; Leslie et al., 1990a,b). In particular,

magnetic iron sulfides can be produced through a number of different

processes: (1) bacterially mediated synthesis of single-domain greigite,

in the form of magnetosomes produced by magnetotactic bacteria

(Mann et al., 1990; Bazylinski et al., 1993), and/or (2) precipitation

from pore waters, and/or (3) dissolution of detrital iron oxides and

subsequent precipitation of iron sulfides.

Authigenic growth of iron sulfides is a common and relatively well-

understood process in anoxic sedimentary environments with rela-

tively high organic carbon contents (e.g., Berner, 1984; Leslie et al.,

1990a,b; Roberts and Turner, 1993). Authigenic magnetic iron sulfides

Figure I32 (a) Backscattered electron micrograph of an iron

sulfide nodule from the Valle Ricca section, Italy (see Florindo

and Sagnotti, 1995). The nodule shows evidence for multiphase

sulfidization and contains framboidal pyrite (Py) and greigite (G),

which always occurs with finer crystal sizes than the co-occurring

pyrite, and intergrown plates of hexagonal pyrrhotite (Pyrr).

(Courtesy of Andrew P. Roberts and Wei-Teh Jiang.)

(b) Backscattered electron micrograph of a Trubi marl sample

from Sicily (see Dinare

s-Turell and Dekkers, 1999) showing

framboidal pyrite (Py) filling foraminifera shells and pyrrhotite

(Pyrr) intergrown plates dispersed in the rock matrix. (Courtesy of

Jaume Dinare

s-Turell.)

456 IRON SULFIDES

(pyrrhotite and greigite) are intermediate mineral phases within the

chemical iron reduction series that eventually forms stable paramag-

netic pyrite (FeS

; Berner, 1969, 1970, 1984; Canfield and Berner,

1987). The process can be mediated by bacterial activity that reduces

pore-water sulfate (SO

2þ

) to sulfide (S



) associated with consump-

tion of organic carbon during burial. Hydrogen sulfide (H

S) then pro-

gressively reacts with detrital iron minerals to ultimately produce

pyrite. Intermediate magnetic iron sulfides are metastable with respect

to pyrite in the presence of excess H

S. The major factors controlling

pyrite formation and the preservation of the (magnetic) intermediate

phases in marine sediments are the amounts of dissolved sulfate, reac-

tive iron detrital minerals, and decomposable organic matter (Berner,

1970, 1984). Intermediate magnetic iron sulfides may be preserved

in all cases when the limited availability of sulfide, reactive iron and/

or organic matter prevents completion of the processes that result

in formation of pyrite. In normal marine environments, sulfate and

reactive detrital iron minerals are practically unlimited and the

major controlling factor on the pyritization process appears to be the

availability of detrital organic matter (Kao et al., 2004). In this case,

the small amounts of sulfide produced will rapidly react with dissolved

iron; the rapid consumption of sulfide means that formation of

intermediate greigite is favored over pyrite. However, in some set-

tings, organic carbon may have different sources and greigite has also

been reported to form during later burial as a consequence of the dif-

fusion of hydrocarbons and gas hydrates through permeable strata

(Reynolds et al., 1994; Thompson and Cameron, 1995; Housen and

Mousgrave, 1996).

Greigite is the more common magnetic iron sulfide in fine-grained

sediments; pyrrhotite, however, has also been reported in various

fine-grained sediments, often alongside greigite (Linssen, 1988; Mary

et al., 1993; Roberts and Turner, 1993; Dinarès-Turell and Dekkers,

1999; Horng et al., 1998; Sagnotti et al., 2001; Weaver et al., 2002)

(Figure I32). The relative abundance of reactive iron versus organic

matter appears to be the controlling factor for the transformation path-

way of initial amorphous FeS into greigite or into pyrrhotite (Kao

et al., 2004). Compared to greigite, pyrrhotite is favored by more redu-

cing environments (i.e., lower Eh) and higher concentration of H

both implying a higher consumption of organic carbon (Kao et al.,

2004). Even under appropriate diagenetic conditions, however, mono-

clinic pyrrhotite (Fe

) formation will be extremely slow below

180



C, which makes it a highly unlikely carrier of early diagenetic

remanences in sediments (Horng and Roberts, 2006). The abundance

of monoclinic pyrrhotite in regional metamorphic belts makes it a

likely detrital rather than authigenic magnetic mineral in marginal

basins in such settings (Horng and Roberts, 2006).

During nucleation and crystal growth, authigenic greigite and pyr-

rhotite acquire a CRM, which contributes to the total NRM of the sedi-

ments. Authigenic formation of magnetic iron sulfides is generally

believed to occur at the very first stages of diagenesis and NRM car-

ried by magnetic iron sulfides were used for detailed paleomagnetic

studies, assuming they reflect primary components of magnetization

(e.g., Tric et al., 1991). However, many studies documented a signifi-

cant delay between the deposition of the sediment and the formation of

magnetic iron sulfides, implicating late diagenetic magnetizations. In

particular, sediments bearing magnetic iron sulfides were often

reported to carry CRM that are antiparallel either to those carried by

coexisting detrital magnetic minerals and of opposite polarity with

respect to the polarity expected for the age of the rock unit

(e.g., Florindo and Sagnotti, 1995; Horng et al., 1998; Dinarès-Turell

and Dekkers, 1999; Jiang et al., 2001; Weaver et al., 2002; Oms

et al., 2003; Roberts and Weaver, 2005; Sagnotti et al., 2005). Such

studies demonstrate that magnetic iron sulfides can carry stable

magnetizations with a wide range of ages and that a syndepositional

age should not be automatically assumed.

Leonardo Sagnotti

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Cross-references

Demagnetization

Magnetization, Chemical Remanent (CRM)

IRON SULFIDES 459

JESUITS, ROLE IN GEOMAGNETISM

The Jesuits are members of a religious order of the Catholic Church,

the Society of Jesus, founded in 1540 by Ignatius of Loyola. From

1548, when Jesuits established their first college, their educational

work expanded rapidly and in the 18th century, in Europe alone, there

were 645 colleges and universities and others in Asia and America. As

an innovation in these colleges, special attention was given to teaching

of mathematics, astronomy, and the natural sciences. This tradition has

been continued in modern times in the many Jesuit colleges and uni-

versities and this tradition thus spread throughout the world. Jesuits’

interest in geomagnetism derived from teaching in these colleges

and universities. In many of these colleges and universities observa-

tories were established, where astronomical and geophysical obser-

vations were made (Udías, 2003). Missionary work in Asia, Africa,

and America, where scientific observations were also made and some

observatories established, was another factor in the role of Jesuits in

geomagnetism. In this work we must distinguish two periods. The first,

from 1540 to 1773, ended with the suppression of the Jesuit order. The

second began in 1814 with its restoration and lasts to our times.

Early work on magnetism

Terrestrial magnetism attracted Jesuits ’ attention from very early times

(Vregille, 1905). José de Acosta, a missionary in America, in 1590

described the variation of the magnetic declination across the Atlantic

and the places where its value was zero, one of them at the Azores

islands. His work is quoted by William Gilbert (q.v.). In 1629, Nicolò

Cabbeo (1586–1650) was the first Jesuit to write a book dedicated to

magnetism, Philosophia Magnetica, where he collected all that was

known in his time, together with his own experiments and observa-

tions. Some of his work is based on that of a previous Jesuit

Leonardo Garzoni (1567–1592), professor at the college of Venice,

who could well be the first Jesuit interested in such matters. Cabbeo

was opposed to Gilbert on the origin of terrestrial magnetism. The

best-known early work on magnetism by a Jesuit is that of Athanasius

Kircher (1601–1680) (q.v.), Magnes sive de arte magnetica, published

in 1641. Martin Martini (1614–1661), who sent many magnetic obser-

vations from China to Kircher, proposed to him in 1640 to draw a map

with lines for the magnetic declination. Had his suggestion been fol-

lowed this would have been the first magnetic chart (before that of

Edmund Halley (q.v.)).

A curious work is that of Jacques Grandami (1588–1672), Nova

demonstratio inmobilitatis terrae petita ex virtute magnetica (1645),

in which, in order to defend the geocentric system, he tried to show

that the Earth does not rotate because of its magnetic field. Among

the best observations made in China are those of Antoine Gaubil

(1689–1759), who mentioned that the line of zero declination has with

time a movement from east to west. His observations and those of

other Jesuits in China were published in France in three volumes

between 1729 and 1732. In 1727, Nicolas Sarrabat (1698–1739) pub-

lished Nouvelle hypothèse sur les variations de l’aiguille aimantée,

which was given an award by the Académie des Sciences of Paris.

In 1769, Maximilian Hell (1720–1792), director of the observatory

in Vienna, made observations of the magnetic declination during his

journey to the island of Vardö in Lapland, at a latitude of 70



N, where

he observed the transit of Venus over the solar disk.

Magnetic observatories

The Jesuit order was suppressed in 1773 and restored in 1814. From

this time work on geomagnetism was taken up again at the new Jesuit

observatories (Udías, 2000, 2003). A total of 72 observatories were

founded throughout the world. Magnetic stations were installed in 15

of them: five in Europe, one in North America, four in Central and

South America, and five in Asia, Africa, and the Middle East. Some

of those magnetic stations in Europe were among the first to be in

operation. Observatories in Central and South America, Asia, and

Africa provided for some time the only magnetic observations in those

regions. Details of these observatories can be found in Udías (2003).

At present, most of them have been either closed or transferred to other

administration.

The first of these observatories was established in 1824 at the

Collegio Romano (Rome). There, in 1858, Angelo Secchi (1818–

1878) began magnetic observations, using a set of magnetometers, a

declinometer, and an inclinometer. He studied the characteristics of

the periodic variations of the different components of the magnetic

field and tried to relate magnetic variations with solar activity, consid-

ering the Sun to be a giant magnet at a great distance. Relations

between geomagnetism and solar activity were to become a favorite

subject among Jesuits. In the same year, 1858, magnetic observations

begun at Stonyhurst College Observatory (Great Britain). Stephen

J. Perry (1833–1889, Figure J1) began his work on geomagnetism,

carrying out three magnetic surveys: two in France in 1868 and 1869

and the third in Belgium in 1871 (Cortie, 1890). In each of these sur-

veys, at each station, careful measurements were made of the horizon-

tal component of the magnetic field, magnetic declination, and

inclination or dip (Perry, 1870). In Belgium, Perry found large mag-

netic anomalies related to coal mines. In order to study the relation

between solar and terrestrial magnetic activity, which was still a con-

troversial subject, Perry at Stonyhurst began a series of observations

of sunspots, faculae, and prominences in 1881. For this purpose he

installed direct-vision spectroscopes and photographic-grating spectro-

meters and made large drawings of the solar disk (27 cm diameter).

Perry collaborated with Edward Sabine (q.v.) in this work. Perry parti-

cipated in several scientific expeditions. The most important was to

Kerguelen Island in 1874 to observe the transit of Venus; there he

carried out a very comprehensive program of magnetic observations.

His project of collecting and comparing all his magnetic and solar

observations was never completed due to his untimely death during

a scientific expedition to the Lesser Antilles to observe a solar

eclipse. In 1874 he was elected a Fellow of the Royal Society for his

work in terrestrial magnetism. Perry’s successor Walter Sidgreaves

(1837–1919) completed the work and showed the correlation between

magnetic storms and the maxima of sunspots (Sidgreaves, 1899–

1901). The continuous magnetic observations from 1858 to 1974 at

Stonyhurst may be one of the longest series at the same site.

Solar-terrestrial relations were also the main subject of Haynald

Observatory, founded in 1879 by Jesuits in Kalocsa (Hungary).

Between 1885 and 1917, Gyula Fényi (1845–1927) carried out a long

program of magnetic and solar observations. He concentrated his

efforts on the study of sunspots and prominences, making detailed

observations (about 40000 of them) and proposing some interesting,

for that time, new ideas about their nature. Magnetic observations

began in 1879.

The Manila Observatory (Philippines) was founded by Spanish

Jesuits in 1865. Martín Juan (1850–1888) was trained in geomagnet-

ism by Perry in Stonyhurst. Juan brought new magnetic instruments

to Manila where he took charge of the magnetic section in 1887. In

1888, he carried out a magnetic field survey on various islands of

the archipelago. His death did not allow him to finish the work; this

was done in 1893 by Ricardo Cirera (1864–1932), who extended the

survey to the coasts of China and Japan (Cirera, 1893).

In the observatory of Zikawei, founded in 1872 near Shanghai, mag-

netic instruments for absolute measurements and variations were

installed in 1877; instruments were moved to two nearby sites, first

Lukiapang in 1908 and then Zose in 1933. Results were published in

nine volumes between 1908 and 1932 (Études sur le magnetisme ter-

restre, pp. 1–39). Joseph de Moidrey (1858–1936) carried out some

early work on the secular variation in the Far East region (de Moidrey

and Lou, 1932). These observations continued until 1950 when Jesuits

were expelled from China by the Communist government.

After returning to Spain, Cirera founded in 1904 the Observatorio

del Ebro, Roquetas (Tarragona; Figure J2), dedicated specifically to

the study of the relations of solar activity and terrestrial magnetism

and electricity. The observatory was equipped from the beginning with

the most up-to-date instrumentation for this purpose and has kept

updating its instrumentation since then. Luis Rodés (1881–1939) stu-

died the influence of various forms of solar activity, mainly sunspots

and prominences on the terrestrial magnetic and electric fields (Rodés,

1927). After the Spanish civil war, work was resumed by Antonio

Romañá (1900–1981) and José O. Cardús (1914–). Since 1958, Ebro

has been the base of the International Association of Geomagnetism

and Aeronomy (IAGA) (q.v.) Commission for rapid magnetic varia-

tions. Romañá and Cardús held office in IAGA for many years.

Maintaining magnetic observatories in Africa was a difficult task,

which Jesuits undertook early. One of the earliest observatories was

established in 1889 in Antananarive, Madagascar. Continuous mag-

netic observations were made until 1967 when the observatory was

transferred to the University of Madagascar. A magnetic station was

established in the observatory founded in 1903 in Bulawayo,

Zimbabwe. Edmund Goetz (1865–1933), its director for 23 years, in

1909 and 1914 carried out two magnetic field surveys, the first with

a profile from Broken Hill (Kabwe, Zambia) to the “Star of the Congo

Mine” (Congo) and the second in Barotseland (Zambia) covering a

distance of more than 200 miles from Kazungula to Lealui (Goetz,

1920). The third observatory was a state observatory entrusted to

and directed by Jesuits in Ethiopia. This observatory arose from

a recommendation of the Scientific Committee of the International

Geophysical Year in 1955 for a magnetic station near the magnetic

equator. The station was established in Addis Ababa in 1958 and

directed by Pierre Gouin (1917–) for 20 years. Gouin with the colla-

boration of Pierre Noel Mayaud (1923–), a Jesuit working at the Insti-

tute de Physique du Globe in Paris, studied temporal magnetic

variations and magnetic storms. Mayaud participated in French expe-

ditions to the Antarctica, studied the magnetic activity in the polar

regions and worked mainly on the nature and practical use of geomag-

netic indices (Mayaud, 1980). Early magnetic observations were also

made by Jesuits in Central and South America. These observations

began in 1862 in Belen Observatory (Havana, Cuba) and continued

to about 1920. In Puebla (Mexico), magnetic observations were made

between 1877 and 1914.

Figure J1 Stephen J. Perry (1833–1889), Director of Stonyhurst

Observatory.

Figure J2 Ebro Observatory, Roquetas, Tarragona, Spain.

JESUITS, ROLE IN GEOMAGNETISM 461

Summary

As an important part of their scientific tradition Jesuits dedicated much

of their efforts to the study of terrestrial magnetism. Jesuits’ dedication

to science can be explained by their peculiar spirituality, which unites

prayer and work and finds no activity too secular be turned into prayer.

Teaching mathematics and observing the magnetic field of the Earth or

of the Sun are activities, as has been shown, that a Jesuit finds per-

fectly compatible with his religious vocation and through which he

can find God in his life. Early work on magnetism was carried out

in the 17th and 18th centuries. Jesuit missionaries during those centu-

ries carried out magnetic observations, which were analyzed and pub-

lished in Europe. Modern work was done through the establishment of

observatories. In at least 15 of these observatories magnetic observa-

tions were made. Jesuits contributed to the earliest magnetic obser-

vations in Africa, Asia, and Central and South America.

Agustín Udías

Bibliography

Cirera, R., 1893. El magnetismo terrestre en Filipinas. Manila: Obser-

vatorio de Manila, 160 pp.

Cortie, A.L., 1890. Father Perry, F.R.S.: The Jesuit Astronomer.

London: Catholic Truth Society, 113 pp.

Goetz, E., 1920. Magnetic observations in Rhodesia. Transactions of

the Royal Society of South Africa, 8(4): 297–302.

Mayaud, P.N., 1980. Derivation, Meaning, and Use of Geomagnetic

Indices. Geophysical Monograph 22. Washington, D.C.: American

Geophysical Union.

Moidrey, J. de and Lou, F. 1932. Variation séculaire des éléments mag-

nétiques en extreme orient. Études sur le magnetisme terrestre 39,

Observatoire de Zikawei, 9:1–21.

Perry, S., 1870. Magnetic survey of the west of France in 1868.

Philosophical Transactions Royal Society of London, 160:

33–50.

Rodés, L., 1927. Some new remarks on the cause and propagation of

magnetic storms. Terrestrial Magnetism and Atmospheric Electri-

city, 32: 127–131.

Sidgreaves, W., 1899–1901. On the connection between solar spots

and Earth magnetic storms. Memoirs of the Royal Astronomical

Society, 54:85–96.

Udías, A., 2000. Observatories of the Society of Jesus, 1814–1998.

Archivum Historicum Societatis Iesu, 69: 151–178.

Udías, A., 2003. Searching the Heavens and the Earth: The History of

Jesuit Observatories. Dordrecht: Kluwer Academic, 369 pp.

Vregille, P. de, 1905. Les jésuites et l’étude du magnétisme terres-

tre. Études, 104: 492–511.

Cross-references

Geomagnetism, History of

Gilbert, William (1544–1603)

Halley, Edmond (1656–1742)

IAGA, International Association of Geomagnetism and Aeronomy

Kircher, Athanasius (1602–1680)

Observatories, Overview

Sabine, Edward (1788–1883)

462 JESUITS, ROLE IN GEOMAGNETISM

KIRCHER, ATHANASIUS (1602–1680)

Athanasius Kircher was born in Geisa near Fulda (Germany) on May

2, 1601 (or 1602—there is a disagreement in his biographies). After

his primary education at the Jesuit school in Fulda, he joined (October

1618) the Jesuit order in Paderborn, where he began to study Latin and

Greek. As a consequence of the Thirty Years War he went to Münster

and Cologne, where he studied philosophy. He taught for a short time

at the secondary school in Coblenz and afterward in Heiligenstadt. Later

he went to Mainz to study theology, where he was ordained priest in

1628 and at the end of his Jesuit training was appointed professor of

ethics and mathematics at the Jesuit University in Würzburg. He again

migrated as a result of the war and went to Avignon (France) and was

finally appointed professor of mathematics and oriental languages at

the Roman College, which is now the well-known Gregorian University

in Rome, where he died on November 27, 1680.

One cannot use modern standards of scientific evaluation to under-

stand his real value, as Kircher’s thinking and his methods are typical

for the 17th century. First of all, he was a polymath interested in

almost every kind of knowledge. His books (over 30 printed volumes)

range from oriental languages—Arabic grammar; translation of old

Coptic books and an extensive research to decipher Egyptian hiero-

glyphics: Lingua Egyptiaca restituta (1643), Oedypus Egyptiacus

(1652), Obeliscus Pamphilius (1650)—to physics—optics: Ars Magna

Lucis et Umbra (1646); magnetism: Ars Magnesia (1631), Magnes,

sive de Arte Magnetica (1641, 1643, 1654), Magneticum Naturae

Rerum (1667); music: Musurgia Universalis sive Ars Magna consoni

and disoni (1650), Phonurgia Nova (1673); geophysics: Mundus Sub-

terraneus (1664); and also medicine: Scrutinium physico-medicum

contagiosae luis quae pestis dicitur (1657). He also wrote on bib-

lical subjects such as Arca Noe (1675) and Turris Baabel (1679),

in which he combines science and archeological imagination. This

imagination together with his knowledge of many different subjects

inclined him to encyclopedism as in his works Itinerarium Extati-

cum (1656) and Iter Extaticum II (1657), in which he discusses

theories of the solar system and beyond while telling the fictitious

story of an imaginary journey through Earth and celestial bodies.

Kircher tries to find some sort of unity among the many different

subjects with which he dealt, not only in written language —Polygra-

phia nova universalis (1663)—but also in the much more universal

concept of knowledge itself as in Ars Magna Sciendi (1669). Although

mathematical combinations in Kircher’s book are far removed from

the cabalistic usage, which was so frequent in his time, there is a

misleading use of the word “magnetism” in his writings: for him mag-

netism with its two polarities is a metaphorical symbol of the dualism

in things and forces acting in nature: attraction and repulsion; love and

hatred; and light and darkness. This use allows him to talk about the

magnetism of celestial bodies, music, medicine, love, and to print, per-

haps for the first time in a scientific book, the word electromagnetism

(Kircher, 1654, p. 451), although this word has nothing to do with the

concept introduced many years afterward by Maxwell.

He was certainly dominated by Baroque culture, redundant in many

aspects of his expression, overlengthy in his writings, and not easy to

read in his Latin, which is far removed from the classical language.

That Kircher was accepted during his lifetime as one of the best scho-

lars in Europe is proven by the fact that the Imperial Court in Vienna

invited Kircher to be professor of astronomy in the University of

Vienna as successor of Kepler, who died in 1632. It was only by the

influence of Cardinal Barberini and of Pope Urban VIII that he was

prevented from accepting the post, and was called to Rome. They

accepted the request of the French gentleman Nicolaus Claude de

Peiresc, who wanted Kircher to continue his work on the interpretation

of Egyptian hieroglyphics. Since his death importance of Kircher as a

scientist has been much debated although now his value seems to be

accepted again.

Of the three books that Kircher wrote on magnetism the first Ars

Magnesia

(his first printed book) is a short booklet of 48 pages and

seems to be the printed edition of a talk he gave some years earlier

when he was teaching at Heiligenstadt. That can be inferred from the

explanation that follows the title where he says he will deal with the

nature, force, and effects of the magnet together with several applica-

tions of it. In the third book, Magneticum Naturae Rerum, the word

“magneticum” is taken in the metaphorical sense that includes all

forces that act on all things in nature.

The second book Magnes sive de Arte Magnetica Opus Tripartitum

(Kircher, 1654) (a copy of its 3rd edition is in the library of the

Ebro Observatory) contains the scientific contribution of Kircher to

geomagnetism. It is divided into three “books:”

1. On the Nature and Properties of the Magnet

2. The Use of the Magnet

3. The Magnetic World

In the first book Kircher tries to investigate what magnetism is,

using as a starting point what was known in his time: the natural exis-

tence of loadstones, the fact that iron may become magnetic with two

poles acting in opposite senses on other magnetic bodies. He also

accepts the hypothesis of the Earth being a magnet after repeating

Gilbert’s experiments with the terrella, but it is easy to see that the

data is too poor to explain what magnetism is.

In the second book, Kircher shows with the help of several experi-

ments how magnetic force is distributed in magnetic bodies of differ-

ent shapes and how to find what he calls the barycentre. He tries to

show that in a spherical body magnetism propagates linearly to the

poles in its interior and spherically to the poles in the exterior. He finds

that both poles have equal force and explains how to make magnetic

needles to measure inclination and declination accurately. For him it

is a well-established fact that “in the Boreal Hemisphere there is a dis-

tribution of inclination in accordance with latitude, whether it exists

also past the equator I do not know, as to my knowledge nobody has

studied these concordances” (Kircher, 1654, p. 295). At this point he

accepts the idea already given by Gilbert and prints a table of magnetic

inclinations for each degree of northern latitudes. He includes his own

calculations and some of Gilbert’s values (Kircher 1654, p. 306).

Declination is treated quite differently in Kircher’s works: he

accepts that its value is related with geographical position but he does

not believe that it depends only on longitude because it deviates from

the local meridian either eastward or westward and also because it

changes values at different latitudes on the same meridian. The solu-

tion of this point is of greatest importance in geography and naviga-

tion. He also realized the errors of many of these values: “there is no

doubt about declination, the only doubt is in its quantity (¼value)”

and a little afterward he adds “the only way to get out of this problem

is to make all around the world as many reliable observations as pos-

sible” (Kircher, 1654, p. 313) and for Kircher it was easy to see that

his Jesuit order, with many colleges in Europe and missionaries tra-

veling to America and Asia, could be a reliable instrument to perform

this task.

After talks with his colleagues in Rome and with the approval of his

superior general, he prepared a Geographical Consilium (an instruc-

tion manual) about declination and inclination, what kind of instru-

ments were needed, how to use them, and how to report the results.

On the occasion of one of the regular meetings of Jesuits from around

the world in Rome in 1639, Kircher collected names of Jesuits who

could do the work and wrote letters to all of them.

Three long tables are the result: the first one (Table K1) “Magnetic

declination on the oceans observed by Jesuits” is a long list of nearly

200 geographical points with their declination and latitude. The lati-

tudes extend as far as from 81



Nto54



S, and the declinations

from 25



Eto35



W. Table K2 “Longitudes and latitudes of sev-

eral places with their declination” seems to be arranged in increasing

longitude from 0



to 359



, but longitudes from 347



359



are included between 41



and 42



. Declinations go from



0’ to 33



. There is no indication whether they are to the east or to the

west, but the fact that longitudes from 42



to 346



are listed at the end

of the table may suggest some elaboration of the data, which are not

explained by Kircher. Table K3 is the list of declinations observed in

Europe following Kircher’s request. The names of some 57 authors

and of 66 cities in Europe with their declination are mentioned in it.

Values in the list extend from Lisbon to Constantinople and from Vilna

to Malta. Kircher adds six other cities: Aleppo (Syria), Alexandria

(Egypt), Goa and Narfinga (India), and Canton and Macau (China).

Behind this third table Kircher adds the copy of a letter from Francis

Brescianus, who observed in his travel westward to Canada the fol-

lowing declination changes: from Europe to a place near the Azores

the declination was around 2



Eor3



E, at the Azores it was about



, from there for some 300 leagues it increased regularly up to around



or 22



and from there it decreased again but more quickly as one

approached America. In Quebec it was 16



and further west, in the

land of the Huron Indians, some 200 leagues from Quebec, it was only



. Kircher adds also a letter from his pupil in Rome, P. Martin s.I.

with 13 declinations but their geographical positions are too vague

as “in the meridian of river Laurentij Marques” (Kircher, 1654,

p. 348). In this letter Martin suggested a method for drawing a world

chart of declination. This suggestion was not followed by Kircher

and the first isogonic chart of the Atlantic was not published until

1701 by Edmund Halley (Chapman and Bartels, 1940).

Unfortunately, the final result of all this observational work was

never completed. As Kircher says: “When I was keeping the work,

composed with no small effort, in my Museum and waiting for the

right moment to publish it for the good of the Republic of Letters, it

was secretly removed by one of those people who came to me almost

every day from all around the world to see my Museum” (Kircher,

1654, p. 294).

This combined and centralized effort is probably the first one of that

kind in magnetism and must be considered as the great contribution of

Kircher to the advancement of geomagnetism. It is certainly not a

milestone on the long way of progress in science but it is an important

step in it.

Oriol Cardus

Bibliography

Chapman, S., and Bartels J., 1940. Geomagnetism. Oxford: The

Clarendon Press.

Diccionario Histórico de la Compañía de Jesús, 2001. Comillas

(4 volumes).

Kircher, A., 1654. Magnes sive de Arte Magnetica. 3rd edn. Rome.

Virgille P. de, 1905. Les Jesuites et l’étude du magnetisme terrestre.

Etudes, 492–511.

Cross-references

Gilbert, William (1544–1603)

Halley, Edmond (1656–1742)

Observatories, Overview

464 KIRCHER, ATHANASIUS (1602–1680)

LANGEL, ROBERT A. (1937–2000)

A NASA (UnitedStates) scientist who served as the project scientist

for the Magsat mission. Trained as an applied mathematician and

physicist, Langel was born in Pittsburgh, Pennsylvania. He was a

strong advocate of high-accuracy vector magnetic measurements from

satellite. These measurements were used to demonstrate the break in

the power spectra at about spherical harmonic degree 13 that repre-

sents the transition from core-dominated processes to lithospheric-

dominated processes (Figure L1; Langel and Estes, 1982). Tantalizing

suggestions of such a break had previously been reported from total

field-intensity measurements acquired on an around-the-world mag-

netic profile (Alldredge et al., 1963). Langel also made use of the

high-accuracy vector measurements, and magnetic-observatory mea-

surements, for the coestimation of internal (core and lithosphere),

external (ionosphere and magnetosphere), and induced magnetic

fields. These comprehensive models of the geomagnetic field were

developed in collaboration with T. Sabaka (NASA) and N. Olsen

(Denmark). Earlier workers had relied on a sequential approach, begin-

ning with the largest (core) fields. Langel also pioneered mathematical

techniques for the merging of a priori long-wavelength lithospheric

magnetic field information with shorter wavelength observations (Fig-

ure L1; Purucker et al., 1998) using inverse techniques. This is neces-

sary because the longest-wavelength lithospheric magnetic fields are

inaccessible to direct observation as they overlap with the much-larger

magnetic fields originating in the Earth’s outer core. Significant earlier

developments with forward models came from Cohen (1989) and

Hahn et al. (1984). Langel authored or coauthored in excess of 94

peer-reviewed publications and helped train a generation of geomagne-

tists by virtue of his work on Magsat and his teaching at Purdue Uni-

versity (UnitedStates) and Copenhagen University (Denmark).

Bob was devoted to his family and church. His religiosity was well

known among his colleagues, and he undertook missionary work, lead

Bible study groups, and worked with teenagers.

Michael E. Purucker

Bibliography

Alldredge, L.R., Vanvoorhis, G.D., and Davis, T.M., 1963. A magnetic

profile around the world. Journal of Geophysical Research, 68:

3679–3692.

Cohen, Y., 1989. Traitements et interpretations de donnees spatiales in

geomagnetisme: etude des variations laterales d’aimantation de la

lithosphere terrestre. Docteur es sciences physiques these, Paris:

Institut de Physique du Globe de Paris, 95 pp.

Fox Maule, C., Purucker, M., Olsen, N., and Mosegaard, K., 2005.

Heat flux anomalies in Antarctica revealed by satellite magnetic

data. Science, 10.1126/science.1106888.

Hahn, A., Ahrendt, H., Meyer, J., and Hufen, J.H., 1984. A model of

magnetic sources within the Earth’s crust compatible with the field

measured by the satellite Magsat. Geologischer Jahrbuch A, 75:

125–156.

Langel, R.A., 1987. The main geomagnetic field. In Jacobs, J. (ed.),

Geomagnetism. New York: Academic Press, pp. 249–512.

Figure L1 Comparison of the Lowes-Mauersberger spectra at the

Earth’s surface for a recent comprehensive model (line) of the core

and lithospheric fields by Sabaka et al. (2004) and a

lithospheric field model (symbols) by Fox Maule et al. (2005).

is the mean square amplitude of the magnetic field over a

sphere produced by harmonics of degree n.