Untitled

PROGRESS OF DISCOVERY. 181
general tableau. The measurements lack precision, or have merely a general value,
and the li, or unit of distances, changes according to time and place. The li is
usually estimated at one-third of a mile, but there are great discrepancies, and 185,
192, 200, and 250 are variously reckoned to the degree.
The itineraries of the first European explorers are often traced in a somewhat
vague manner, and of these pioneers of discovery very few have left a name in
history. Marco Polo, who spent seventeen years in the country, was followed by
other traders or missionaries, such as Pegolotti, Montecorvino, Odorico di Pordenone,
Fig. 64. KIANQ-SU, ACCORDIKO TO MARTINI.
NANKING;
S1VE
KiANGNAN. X
IMPERII SJNARVM
PROVINCIA NONA. V
f^^Tj*"
Marignolli. In his description of the splendours of Cansai, the modorn Hangchew-fu,
Odorico appeals to the testimony of many Venetians, who had also visited the
place.
But exploration in the strict sense of the term, together with the direction
or improvement of the native maps, did not begin till the time of the missionaries.
In the seventeenth century Martino Martini, of Trent, reproduced
the Chinese
maps, modified by himself from his own observations, and accompanied by critical
documents. At the end of the same century the French missionaries, having
become the oiliciiil astronomers and mathematicians of the empire while retaining
their relations with the geographers of the West, were able to explore the country