CHAPTER XIV. 



SURVEY WORK OF THE EXPEDITION — BY R. S. CLARK. 



T^HE Map* accompanying this volume is based on the plane-table work 

 carried out by Hazrat Ali, of the Survey of India, the ill-fated member 

 of our party, whose death at the hands of the Chinese near Lan-chou brought 

 the expedition to an untimely close. A short description of the means and 

 methods employed on the survey will, we trust, be found of interest. 



Commencing with a list of the instruments used, and remarking 

 where necessary as to their pattern etc., we give a few notes to indicate 

 briefly the methods employed for fixing our base, for carrying out the whole 

 survey and for determining certain check-measurements ; finally connecting 

 up the results of our work with such records of previous surveys as are 

 available. For the benefit of future travellers itineraries of the routes 

 traversed are given in Appendix I., together with a table containing Latitude, 

 Longitude, and — in most cases — Altitude of every important place visited. 



Instruments, etc. 



The instruments and appliances used were : — 



1 3-inch Astronomical Field Telescope. (Cary London) 



2 5-inch Micrometer Theodolites. ( ,, ,, ) 



3 Half-Chronometer Watches. (Blockley, Kew certificated) 

 I Half-Chronometer Watch with Chronograph. 



3 Aneroid Barometers. (Cary) 



I Boiling-point Thermometer. ( ,, ) 



I Georges Mercurial Barometer. ( ,, ) 



I loo-foot Invar Tape. 



I Plane-table. 



I Road-wheel. 



Base-lines. 



(A) As described in Chapter I, the party went into camp a few 

 miles out of T'ai-yiian Fu to measure a base-line, the site chosen for 



• In a pocket at the eod of volume. 



130 



