OP CENTRAL AND EASTERN ASIA. 19^7 



per direction as to the points of the compass. But I think 

 there is scarcely an example, that so extensive a line, reaching 

 across nearly half a continent, should be so entirely changed. 

 I believe also that the error occurs chiefly in vague boundary 

 lines, or in coasts, where the vessel, according to ancient prac- 

 tice, followed all the windings of the shore, and was acted upon 

 by various tides and currents. It might then be difficult to as- 

 certain the general line of their course, and an erroneous idea, 

 once formed, might not readily be corrected. But a land- 

 route is in a much more direct line ; and as travellers have an 

 obvious interest to know the direction in which they are mo- 

 ving, so the most superficial observation of the celestial pheno- 

 mena will enable them to avoid any error of great magnitude. 

 Ptolemy, we may observe, enumerates very particularly all the 

 changes of direction made by the great caravan in its course- 

 through Asia. From the passage of the Euphrates to Hecatom- 

 pylos, the capital of Parthia, he makes it east; which that line ve- 

 ry nearly is. Thence to the capital of Hyrcania, north ; that is,. 

 north-east, as east is always understood to be the general direction. 

 Then to the capital of Margiana, by a circuitous route through- 

 Aria, first south, and then north ; to Bactra, east ; to the ascent 

 of the Montes Comedorum, north-east ; which agrees with Mr 

 Elphinstone's map ; then south-east, being the direction of the 

 plain of Little Thibet ; then again north-east, which is the di- 

 rection of the valley of the Ladauk, the established line of 

 communication with Great Thibet. Thus, along the whole of 

 this immense line, the minutest variations are clearly recogni- 

 sed ; and the improbability is greatly increased, that, in the 

 next stage, so extraordinary an error should be committed. 



The merchants farther informed Marinus, that, lengthened 

 as the march now described had been, it formed scarcely half 

 of the peregrination to Sera ; that from the Purgos LWiinos, com- 

 menced 



