Page:Arrian's Voyage Round the Euxine Sea Translated.djvu/190

190 did not dicover that the two places lay under different meridians. The numbers of Eratothenes above pecifed were not however acquieced in by ucceeding atronomers, ince Marinus and Ptolemy allotted, as Dr. Blair oberves, no more than 3600 tadia to that ditance; as the even degrees twelve minutes (a calculation of the latitude not very different from that of Mr. D'Anville before-mentioned) amounted exactly to that number on the proportion of 500 tadia to a degree; which, Ptolemy tells us, was agreeable to menurations allowed and acknowledged.

The learned Prelate's calculations in the next paragraph are rather incorrect. He States the proportion of the Roman foot to the Englih to be as 97: 100; whereas it appears from Greaves, whoe meaurement the Bihop eems to have adopted, to be only 967: 1000; which makes a difference of nearly $1⁄134$ part, and amounts nearly to 16 feet in the pace of an Engliih mile; which, although an inconiderable difference in mall ditances, is neceary to be taken into account in the etimation of large extents; and this error, by over-rating the length of the Roman foot, vitiates in ome meaure his ubequent calculations.

This appears in the next entence of his Lordhip's obervations; where he urges, "that if eight Olympic tadia were equal to a Roman mile, and that Polybius's addition of ⅓ of a tadium was an error of his own, ariing from the difference between the Roman and the Olympic foot, then one Olympic tadium would be 506.25 feet, London meaure;" which computation over-rates the