4 Suggestions for the Yunan Expedition. [Jaw. 



posits, all the available evidence bearing on this head should be got toge- 

 ther. And it need hardly be added that, in all cases where it is possible, 

 measurements should be made, and photographs taken of typical specimens 

 of differing peoples and races, with the view to exhibiting and precisely 

 recording their general appearance and costume, their distinctive facial 

 characteristics and shape of head, both for males and females. 



Meteorology. 



On the march, of course, little can be done in the way of instrumental 

 observations. Wind and cloud observations, however, may be made at 

 all times without the aid of instruments other . than a compass. It is 

 scarcely necessary to say that among the mountains, the winds are great- 

 ly affected by the direction of the valleys, so that the movement of 

 the clouds is the best, and in many cases the only, criterion of that of 

 the great air currents. Advantage then should be taken of any oppor- 

 tunity of observing the direction in which clouds, immediately over-head, 

 drift. The estimated proportion of clear sky (0 to 10), the forms of the 

 clouds, and the general character of weather should also be recorded. 

 On open plateaux, a register of the direction and the estimated force of the 

 wind according to Beaufort's scale is specially important. 



When a halt is made at any place and thus an opportunity of making 

 instrumental observations afforded, the chief points to which attention 

 should be given are the following : — 



1. The diurnal range of temperature in the shade from the maximum 

 and minimum thermometers. Care will be required in selecting a proper 

 place for the thermometers to guard them from being affected by direct 

 radiation to or from the clear sky. 



2.' The minimum temperature of radiation at night should be observed 

 whenever possible by a thermometer placed on forked sticks a few inches 

 above the ground. In taking these observations, it is necessary, if the 

 ground is not level, to place the instrument in a slight hollow, or on black 

 woollen cloth in a shallow box, or it will be affected by the convection of 

 the air, and show a temperature many degrees higher than one protected 

 from this influence. 



3. A few sets of hourly barometrical observations extending from 

 midnight to midnight (or, when this is not possible, from sunrise to sun- 

 set) would be very valuable. It will be interesting to see whether the 

 diurnal oscillation follows the same law as on the Indian plains, or that of 

 the Himalayan hill- stations. 



4. When hourly observations of the barometer are made, those of the 

 hygrometer should be made also. Besides these, observations of the wet 

 and dry bulb thermometers should be taken at other times as often as 

 practicable. 



