132 Across the China-Tibet Frontier 
the scow, the storm burst right overhead, torrents of rain 
pouring down. In the darkness the river, now white with 
foam, was revealed by brilliant flashes of lightning which 
seemed to fill the valley with red fire, and the thunder 
roared amongst the mountains. As the storm had come 
so it passed, travelling rapidly south-east, and the thunder 
grew fainter and fainter till it died away altogether. But 
for an hour the lightning danced far down the winding 
valley, like a candle flickering in a draught at the end of 
a long passage. A long weary tramp leading the ponies 
and stumbling over all sorts of obstacles brought us at ten 
o'clock to the village where we had slept previously, and 
we continued to Pa-mu-t’ang next day. 
On the following morning August 8, we climbed to the 
summit of the eastern watershed, finding the same lime- 
stone towers and vast screes crowning the ridge as above 
A-tun-tsi. Two lakes I found here, at an altitude of between 
16,000 and 17,000 feet, undoubtedly occupied rock-basins, 
and the belief which had been gradually forcing itself upon 
me, that the Mekong-Yang-tze watershed had previously 
been glaciated, became more firmly rooted than ever. 
From the summit of the pass (about 17,000 feet) I 
looked westwards across the Pa-mu-t’'ang valley to the 
rolling hills of the Tibetan plateau, where I caught sight 
of an extensive lake, bearing rather north and some distance 
west of Pa-mu-t’ang, but the weather was so thick that 
I obtained only momentary glimpses of it, and do not 
know either its position or size. 
We returned to Pa-mu-t’ang for lunch and I now sent 
Kin to A-tun-tsi with instructions to go over some of our 
old tracks, collect any seeds that were ripe, and mark down 
all new flowers of any interest, while the rest of our party, 
namely Gan-ton, the soldier from Batang, and myself, with 
two baggage ponies, left the A-tun-tsi road and struck off 
westwards across the plateau by the Jung-lam, the great 
road that crosses Asia from Peking to Kashmir. It was 
miserably cold up here at 14,000 feet, and the rain which 
had held off for a part of the morning, now came down 
worse than ever. 
At the highest point reached we passed the old boundary 
stone marking the frontiers of Tibet and China, set up I 
