16 
HINTS TO TRAVELLERS. 
be covered with palm-fronds, grass, or any other material locally used by 
the natives for building. The floor should not be bare but covered 
with grass or low shrubs. 
The great object of these precautions is to obtain the true temperature 
of the air, and avoid the excessive heating due to the direct rays or 
reflected heat of the sun falling on the thermometers, and the excessive 
Eig. 3. Hut for sheltering Thermometers . 
cooling due to the radiation of heat from the thermometers to a clear 
sky at night. Such a shelter is absolutely necessary when maximum 
and minimum thermometers are used; but can be dispensed with for the 
simple observation of the temperature of the air at a given time. This 
may be effected by securing a rapid flow of air over the thermometer, 
either by causing the air to flow past the instrument or by causing the 
instrument to move rapidly through the air. It has been found by 
