Page 93 - Art In The Age Of Exploration (Great Section on Chinese Art Ming Dynasty)

tively, the altitude of the polestar in a particular hour, which is 28 miles." Columbus had with
37
place. Choosing the most appropriately sized him more than one marine compass, and it is
board, the navigator held it so that the lower possible that the peculiar behavior of these com-
edge appeared to lie on the horizon and the passes recorded in an entry in the journal
upper to touch the celestial body to be observed, resulted from his crossing the agonic line (line
then held the string taut against his nose or of zero magnetic declination; the declination at
between his teeth. The knot nearest to his face the time was about eleven and one quarter
indicated the altitude. The origin and history of degrees in northwestern Europe), and that other
the kamal is obscure, but it may derive from a problems Columbus had with his compasses
similar Chinese device. Its importance in the arose from his having brought with him Flem-
history of European navigation lies in its possi- ish and Genoese compasses whose makers
ble influence on the development of the cross- adopted different values for the declination in
38
staff for nautical use. Kamdls were brought setting the fly. For the early part of his voyage,
back to Portugal and are mentioned, together Columbus had some sort of chart, and he pro-
with conversions of the isba to degrees of arc, posed to make a new navigational chart. To
39
in the sixteenth-century navigational treatises this extent, he had not progressed beyond the
32
of Andre Fires and Joao de Lisboa. The cross- first technological revolution in navigation.
staff was an old instrument; it was probably fig. 4. Cross-staff used for determining the altitude But Columbus did notice the apparent rota-
invented by Levi ben Gersom (1288-1344), a of the Polestar, when the Guards are in a particular tion of the polestar about the celestial pole, and
Jewish philosopher and scientist from southern position. From Pedro de Medina, Regimiento de may have used a mnemonic diagram of the posi-
40
France, whose treatise was translated from navegacion (Seville, 1563), fol. 36 tions of a and (3 Ursae minor is, and he thus
Hebrew into Latin in 1342. Although popular joins his Portuguese contemporaries at the
with astronomers — it was, for example, used by beginnings of astronomical navigation. Of
Bernhard Walther, patron of the astronomer "shadow instrument" (estormento de sombras) astronomical instruments, we read that "he has
Regiomontanus, for observations in Nuremberg during his voyage to Goa in 1538 —a culmina- suspended the use of the quadrant until he
from 1476 to 1504 —nothing suggests that it tion, indeed, of the application of science to reaches land and can repair it"; later, that "he
was used at sea before the sixteenth century, navigation. 35 found from his quadrant that he was 34 degrees
although it was certainly in use by 1524. The The first voyage of Columbus in 1492 places [in fact nearly 20° N] from the equinoctial line";
cross-staff was usually of hardwood, sometimes him at the midpoint in this technological devel- and then that the "north star seemed to him to
of brass, and consisted of a square-sectioned rod opment. He had with him a number of instru- be as high as at Cape St Vincent... [but he]
(the "staff") with a sliding cross-bar (the mental aids. Their value to him, as revealed in could not measure its elevation with the astro-
"transversary"). It could be used vertically or the journal of his first voyage, appears ambigu- labe nor the quadrant because the waves would
41
horizontally to measure angular distances, by ous, his instinctive seamanship often in conflict not let him." What sort of astrolabe this was
holding the end of the staff to the eye and with the data he obtained from the instruments. remains unknown.
sliding the transversary until its extremities The journal includes many observations of "The American," wrote the philosopher
appeared to touch the objects between which the flocks of birds (and in one place notes that he Georg Christoph Lichtenberg, sometime
angle was to be measured. 33 knew that the Portuguese had discovered most between 1779 and 1783, "who first discovered
42
By the end of the fifteenth century, then, of the islands they held by observing the flight Columbus made a bad discovery." This aware-
instruments were being adapted or invented for of birds) and records how Columbus changed ness of the interaction and conflict of cultures
the purposes of the new astronomical naviga- course because of these observations. Sticks as a result of European mercantile and mission-
tion. There was no nascent instrument-making floating in the sea are also noted as evidence of ary expansion is a dominant theme of this
industry in Portugal or Spain, so the manufac- land, and the presence of rock weed and reeds is exhibition. This brief essay has not sought to
ture and certification of instruments for naviga- mentioned; the lesser saltiness of the sea near trace in time or space the stages of Portuguese
tors was controlled by the cosmographers, land is commented upon. Columbus' use of the or Spanish colonial enterprise along the coast of
unlike in the Netherlands and in England. lead and line is evidenced by references to the Africa, to farther Asia, or to the Americas, but
There instrument-making workshops existed to seabed being sandy, not rocky, at a depth of fif- rather to consider the intellectual endeavor
fill the demand that arose later in the sixteenth teen or sixteen fathoms; to the existence of a engaged, to borrow the words of Borges, in
century, when the navigators of those countries good entrance to the mouth of a river found by "deciphering the magical alphabet of the stars in
came to adopt astronomical techniques and taking soundings; and to the sea bottom being other latitudes." 43
36
instruments, first based on the Iberian experi- beyond a forty-fathom plumb-line. He
ence and then on their own technical contribu- apparently used half-hour sandglasses: "Here
tions. The appointment in 1529 of Pedro Nunes the Admiral measured the length of the day and
(1502-1578) as royal cosmographer introduced night in hours, and found that from sunrise to NOTES
into Portuguese navigation a truly mathematical sunset was 20 half-hour glasses, although he i. Fernando Pessoa (1888-1935). "Mar portugues,"
34
overview of the colonial enterprise. Nunes says that there could be an error either because Mensagem xxx: 'O salty sea, how much of your salt
.
became professor of mathematics at Coimbra by they do not turn the glass soon enough or / Are tears of Portugal/ .. Was it worth it? Every-
1544 and chief royal cosmographer in 1547; because some of the sand has not passed thing is worthwhile / If the soul is not mean. /
... God gave the sea danger and depth / But in it
among his pupils were the astronomer Chris- through"; and "he sailed for about 14 half-hour mirrored the sky", quoted from F. E. G. Quinta-
toph Clavius and also the naval commander Joao sand-glasses or a little less until the end of the nilba, ed. & trans., Fernando Pessoa. Sixty Portu-
de Castro, who tested Nunes' newly devised first quarter watch, and made about 4 miles an guese Poems (Cardiff, 1971), 46-47.

92 CIRCA 1492