3. He says (iii. 39. 8) that he calculated the 1600 from Ampurias to the crossing of the Rhone by the milestones on the Roman road, reckoning eight stades to a Roman mile. Thus, in Roman miles his distances would be 325 to the Ebro, 200 to Ampurias, 200 to the Rhone, 175 along the river, and 150 across the Alps. He also says (iii. 56. 3) that Hannibal took fifteen days in marching the 1200 stades, and (iii. 50. 1) took ten days in marching 800, part of the 1400. Both cases give an average of 80 stades or 10 Roman miles a day; and this looks as if he knew the time employed here but did not know the distance covered, and therefore calculated the distance from the time. He certainly knew the time employed upon the march of fifteen days, as he elsewhere gives the days in detail, iii. 50. 5, 8, 52. 1, 2, 53. 5, 6, 9, 54. 4, 55. 6, 8, 56. 1. But Hannibal would not really have gone at the same pace on the fifteen days when he was fighting his way through the mountains as on the ten days when he was marching up the river unopposed. Polybios must have taken a standard rate, and used it indiscriminately when he had no help from milestones. 4. After giving distances which amount to 8400 stades or 1050 Roman miles in iii. 39. 6–10, he goes on in iii. 39. 11 to give their total as about (_peri_) 9000 stades or 1125 Roman miles. There must be an error in the total or the items. I fancy the total should be 8000 stades or 1000 Roman miles, as he was more likely to reckon 1050 as ‘about’ 1000 than as ‘about’ 1125. He mentions (iii. 56. 3) that Hannibal took five months on the march; and 150 days for the 1050 miles gives an average of 7 Roman miles a day. Large forces could not move fast. The column would be some miles in length, and the advance-guard might be close to the new camping-ground before the rear-guard left the previous camp; and time would have to be allowed for the rear-guard to come up. 5. Strabo was 150 years junior to Polybios; but the Roman road from Spain would not have moved, and he says (iv. 1. 3) that it crossed the Rhone at Tarascon. He goes on to say that it bifurcated there, one branch going through Aix to Antibes on the Mediterranean coast, while the other went through Cavaillon and along the Durance to the beginning of the ascent (_anabasis_) of the Alps, 63 miles from Tarascon, thence to Embrun, 99 miles further on, and thence through the Briançon district in 71 miles to Césanne, the first town in Italy. (The road must thus have crossed the Alps by the pass of Mont Genèvre.) Strabo here treats the beginning of the ascent of the Alps as a definite point, marked by a milestone, just as Polybios treats the ascent of the Alps and the crossing of the Rhone as definite points from which measurements could be made.