PREFACE 
IX 
certain of the stations were already known with scientific 
exactitude ; these data I employed as bases for the 
determination of the longitudes of the remaining places. 
By this means too I was enabled to check more effectually 
the accuracy of my chronometers, a circumstance the more 
needful seeing that these latter were frequently subjected 
to the rough vicissitudes of travel through difficult regions. 
I brought home latitudinal observations for seven fresh 
places, and longitudinal observations for six. 
As soon as I passed beyond the fairly well-known 
regions of the Russian Pamirs, I took up, in the summer 
of 1894, the strictly topographical division of my labours, 
and with diopter, plane-table, and calculation of paces 
measured the environs of the lake Little Kara-kul ; next 
I mapped the glaciers of that king of the Central 
Asiatic mountain-giants, Mus-tagh-ata. After that 1 
surveyed every route I travelled over during the years 
1894, 1895. 1896, and the early part of 1897. The.se 
important labours were never for a single day remitted. 
Throughout the whole of the long red line, which marks 
my travels through Asia, there is not a single break 
right away to the day (2nd March, 1897) when I rode 
m at the gate of Peking, and recorded my last entry 
on the five hundred and fifty-second sheet of my field- 
book or surveying journal. 
In making these measurements I used only a compass 
and a base-line. The latter varied from 200 (656 feet) 
to 4C0 (1312^ feet) metres, and was in every case 
accurately measured with the metre-measure. After 
measuring my base-line, I carefully noted the time it 
took the caravan, properly laden and travelling at its 
ordinary average pace, to traverse it from the one end 
to the other ; at the same time I was scrupulous to make 
all due allowance for the inclination of the ground and 
other inequalities of the surface. 
