UNITED STATES EXPLORING EXPEDITION. 



203 



U. S. SHIP VINCENNES. 

 MATAVAI BAY, TAHITI. 



OBSERVATORY, POINT VENUS, TAHITI. 



INSTRUMENTS USED ON SHORE. 



Barometer (standard). 



Thermometer attached. 



Thermometer 2 feet from soil, with north-and-south exposure. 



Thermometer, the bulb being covered with white wool, in same position. 



lampblack, 



black wool, 



Thermometer in a hole four feet below the surface. 

 Hygrometer (Daniell's). 



The temperature of water, and the thermometer at mast-head, were registered on board the I'. S. Ship 

 Vincenne*. 



