4 
GEOGRAPHY. 345 
pacty in the meafurements of the ancients, he juftly ftatea 
at five feet. * 
Such was the imperfeil fiate of geography, and the 
inaccuracy of maps, prior to the diicpveries of Hippar- 
chiis; wJio, like an abler architect, introduced a new 
plan of building, more certain in its principles, and more 
fimple in its conflrudtion, and where they miglit employ 
without wafte all the better parts of the aiicient mate¬ 
rials. His additions tended to make a new and clofer 
union betwixt aftronomy and geography, from w'hich 
they derived mutual advantages, and widened their bot¬ 
tom for tlte acceffion of new improvements. 
It appears that war has generally given rife to the 
moft accurate maps of different countries ; and therefore 
geography, about this era, began to make confiderable 
advances from the progrefs of the Roman arms. For 
that warlike people, as they were the conquerors, fo 
they became the furveyors, of the w'orld. In all the 
provinces they occupied, we find that camps were every 
where conftrufted at proper intervals, and roads were 
raifed with fubftantial materials for an eafy communica¬ 
tion between thefe different places of encampment ; fo 
that civilization and furveying were carried on according 
to fyftem, through the whole extent of that large do¬ 
main. Every new wai,' produced a new furvey and itine¬ 
rary of the countries where the feenes of adtion paffed ; 
fo that the materials of geography were accumulated by 
every additional conquefl. Polybius, when he tells us, 
that at the beginning of the fecond Punic war, Hannibal 
was pi'eparing his expedition againfl: Rome, by eroding 
from Africa into Spain, and through Gaul into Italy, 
fays, that all thefe places were meafured or furveyed 
with the utmoft care by the Romans. 
Without entering into the minuter execution of the 
furveys of particular provinces with which every Roman 
general was regularly furnifhed before his march, and 
which Vegetius has well deferibed, we fhall only add a 
remarkable fa£t preferved to us by j^thicus in the Pre- 
face to his Cqfmographia. We are there informed, that 
Julius Ctefar ordered a general furvey to be made of the 
whole Roman empire by a decree of the fenate ; the fur¬ 
veyors are faid to have been men of great wifdom, and 
inftrudted in every branch of philofophy. The three 
furveyors were Zenodoxus, Theodotus, and Polyclitus, 
and were each of them appointed to furvey a different 
divifion of the empire. It began in the confulfliip of 
Julius Csefar and Marc Antony, B. C. 44, and continued 
for twenty-five year# one month and ten days, to the 
confullhip of Sentius Saturninus and Lucretius Cinna, 
B. C, 19, The eaftern part of the empire w'as afligned 
to Zenodoxus, who finifhed it in fourteen years five 
months and nine days, being in the confulfliip of Au- 
guftus IV. and Craflus, B. C. 30. The northern part 
was completed by Theodotus, in twenty years eight 
months and ten days, in the confulfliip of Auguftus X. 
and Flaccus, B. C. 24. And the fouthern part was fi- 
niflied by Polyclitus, in twenty-five years one month and 
ten days. 
The Roman Itineraries that are ftill extant, fliow evi¬ 
dently with what accuracy their furveys W'ere made in 
every province: and Pliny has filled the third, fourth, 
and fifth, books of his Xatural Hiftory, with the geogra¬ 
phical diftances that were thus meafured. We have 
likewife one ancient fet of maps ftill preferved to us, 
known by the name of the Peutingerian Tables, publilhed 
by Welfer and Berlins, which give a fufiicient fpecimen 
®f what Vegetius calls tht Itinera PiBa, for the clearer 
direftion of the march of their armies. 
The Roman empire had been enlarged to its greateft 
extent, and all its provinces well known and furveyed, 
when Ptolemy, in the days of Antoninus Pius, about 
150 years after Chrift, compofed his Syftem of Geogra¬ 
phy, which has been happily preferved to us amidft the 
general wreck that confumed fo many other books of 
fcience. The materials then extant, and in his poflef- 
VoL VIII. No, 507, 
■mon, for the completing of that great work, confifted of 
various particulars, fome of greater and others of a lefs 
degree of authenticity. The principal were the propor¬ 
tions of the gnomon to its fltadow, taken by different 
aftronomers at the times of the equinoxes and folftices ; 
calculations founded upon the length of the longeft 
days; the meafures or computed diftances of the prin¬ 
cipal roads, contained in their furveys and itineraries, 
and the various reports of travellers and navigators, 
who often determined the intervals of places by hear-fay 
and guefs-work. All of thefe were to be compared to¬ 
gether, and digefted into one uniform body or fyftem, 
and after this were converted and tranflated by him into 
a new mathematical language, expreffing their different 
degrees and minutes of latitude and longitude, according, 
to the invention of Hipparchus, but which Ptolemy had 
the merit of carrying into full praftice and execution, 
after it had been negledted for upv.'ards of 250 years. 
No author has ever fuppofed that Ptolemy had in his 
poffeflion real aftronomical obfervations fufficient to de¬ 
termine all the longitudes and latitudes he has laid downj 
lb that we muft always remember that their degree of 
accuracy depended upon the veracity of the fab! or fug- 
geftion communicated to him, from whicli tltey were af¬ 
terwards deduced. Agreeable to this id-ca, we find that 
Regiomontanus, in his Commentary upon Ptolemy’s 
Geography, quoted by Gefner, though never publilhed, 
endeavoured to explain an inftrument called meteorofeo- 
pivm, by which he fuppofes Ptolemy reduced and brought 
forth the numbers of his geography. We muft not there¬ 
fore be furprifed at the multitude of errors to be found, 
when his original materials tvere fo imperfeft for exe¬ 
cuting fo large a work as the fixing the longitudes and 
latitudes of all the places, coafts, bays, and rivers, of the 
then known world; an undertaking which even in our 
days has not yet been brought to fufficient accuracy. 
It was almoft impoftible for him not to have commit¬ 
ted many miftakes in the places beyond the extremities 
of the Roman empire, w'hich were indeed out of the 
range both of aftronomers and furveyors. So that tliofe 
learned writers who have fo feverely criticifed fome 
of his errors, have not treated him with that candour 
and liberality which a work of this nature deferved. His 
miftakes arole from the ignorance of the age in which 
he lived, which could give him no better information, 
and were not properly the perfonal ignorance of the au¬ 
thor. And this remark ought to have its due weight 
in reftraining the wantonnefs of criticifm in a thoufand 
inftances. Ricciolus, Cellafius, Paul Merula, and Sal- 
mafius, have all of them committed this miftake in their 
cenfures of his geography, as if they were difappointed 
in not finding this fcience in its full maturity in the wri¬ 
tings of Ptolemy, at a time when it was evidently but 
juft beginning to emerge from its infantine ftate. 
If the obl'ervations from which Ptolemy compiled his 
geography, had been as accurate as the principles upon 
which it was digefted were well founded, then this fci¬ 
ence would have advanced much fooner towards matu¬ 
rity. But when premifes are admitted to be true, which 
are either doubtful or falfe, then the conclufions drawn 
from them muft alfo be erroneous. Now the principal 
miftakes in Ptolemy took their rife from certain aftrono¬ 
mical obfervations and furveys, which were fuppofed to 
have been made with accuracy in an age prior even to 
Ptolemy himfelf j and as that great author received and 
adopted them as genuine, having none more authentic 
by which their accuracy might have been tried, and 
haying otherwife no reafon toTufpeft them ; fo fucceed- 
ing geographers, for want of better information, were 
induced to copy and infert them in their maps, as being, 
in their opinion, of acknowledged and undoubted au¬ 
thority. And thus error, when it has once alfumed the 
counterfeit ftamp of truth by the unguarded conceflion 
of fome eminent writer, often preferves its currency 
during a great length of time. For thefe miftakes kept 
4 T their 
