HUNAX— THE CLOSED PROVINCE OF CHINA 399 



River, making so long a detour to reach this low gap that this route 

 has not been used as mucli as the Meling on the extreme east, 

 or the most celebrated of the three passes, tlie Cheling, in the center. 

 The Cheling Pass represents a land portage of 15 miles on either side 

 of the mountains between the navigable waters of the Yutan on the 

 north and the Wei River on the south. Baron Richtofen determined 

 its elevation b}^ barometer observations as about 1,000 feet above sea- 

 level. Mr Morrison, the English engineer, when he crossed the pass 

 in 1878, estimated the elevation by the same approximate method as 

 1,200 feet. The instrumental survey made under my direction de- 

 termined the elevation to be 1,190 feet, which probably represents 

 the correct elevation within a very narrow possible margin of error. 

 It is a singular fact, however, that the Chinese failed to find the low 

 point at Cheling. As soon as I began the work of reconnaissance 

 across the range, in order to make out the best route for the survey 

 line to follow, I discovered that the Chinese in building this highwa}^ 

 three or four thousand years ago, had quite failed to grasp the true 

 topographical situation. The true pass across the range lies some 

 three miles to the north of the present highway and at an elevation 

 of something like 110 feet lower. 



The rock formation of the range itself is limestone, and, although 

 the valley which marks the pass is sharp and well defined, its pres- 

 ence is almost entirely obscured by the existence of five extraordi- 

 nary dikes crossing the valley from side to side, and through and 

 under which the streams have been obliged to find their way. A man 

 standing at either end of this valley, which has a length of about four 

 and a half miles, would feel absolutel}'^ certain that no valley existed 

 on account of the high walls of limestone, which appear to be a solid 

 barrier. It was only after climbing to some eminence, whence a 

 bird's-eye view of the whole valley' can be ol^tained, that I discovered 

 its existence. 



The dikes occur in pairs at the ends, with a single one crossing the 

 valley at about the half-way point. At the north end these peculiar 

 rock walls have a height of about 00 feet, rising to a sharp edge on 

 top and separated by a well-defined basin 1,000 feet across. At the 

 south end tiie dikes are larger, being al)out 150 feet high and 1,900 

 feet apart. The divide of the Yangtze and China Sea waters occurs 

 just south of tlie ni)rtiiern pair of dikes and is (juite ciearl}' defined. 

 During the rainy season it is ])rol)able that water will be found flow- 

 ing in opposite directions at no greater distance than a few hundred 



