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NOTES AND ILLUSTRATIONS.

With respect to places in the torrid 2one, there wasanother resource.for determining the latitude. This wasby observing the time of the year whan the sun was verticalto any place , or when bodies that stood perpendicular tothe horizon had no shadow at noon-day; the fun’s distancefrom the Equator at that time, which was known from theprinciples of astronomy, was equal to the latitude ofthe place. We have instances of the application of thismethod in the determination of the parallels of Syene andMeroe. The accuracy which this method would admitof, seems to be limited to about half a degree, and thisonly on the supposition that the observer was stationary;for if he was travelling from one place to another, andhad not an opportunity of correcting the observation of oneday by that of the day following, he was likely to deviatemuch more considerably from the truth.

With respect to the longitude of places, as eclipses ofthe moon are not frequent, and could seldom be of use fordetermining it, and only when there were astronomers toobserve them with accuracy , they may be left out of theaccount altogether when we are examining the geographyof remote countries. The differences of the meridians ofplaces were therefore anciently ascertained entirely by thebearings and distances of one place from another, and ofconsequence all the errors of reckonings, surveys , anditineraries, fell chiefly upon the longitude, in the famemanner as happens at present in a ship which has nomethod of determining its longitude, but by comparingthe dead-reckoning with the observations of the latitude ;though with this difference, that the errors, to which themost skilful of the ancient navigators was liable, were fargreater than what the most ignorant ship-master of moderntimes , provided with a compass, can well commit. Thelength of the Mediterranean measured , in degrees oflongitude , from the Pillars of Hercules to the Bay of Iffus,is less than forty degrees; but in Ptolemy’s maps it ismore than sixty, and, in general, his longitudes, countingfrom the meridian of Alexandria, especially toward the

East,