196 



The other self-registei'mg thermometer was placed in a 

 small dressing-room of the boat from which the sun was 

 excluded, but the air freely admitted day and night. The 

 other two thermometers were also protected as far as 

 possible in the same manner. But, I believe, the tem- 

 perature indicated by the thermometer is of necessity 

 really, both by day and by night, above that of the au' on 

 the liver. The walls of the boat radiate during the 

 night some portion of the heat absorbed during the 

 bright sunshine of the previous day, and thus, despite 

 every precaution affect the thermometric results. These 

 results were compared three times daily, and eveiy pre- 

 caution taken to prevent error and ensvire accuracy. The 

 importance of attending to these minute particulars 

 cannot be over-estimated, and to its neglect may fairly be 

 ascribed the discordant statements made by different 

 observers. 



My own observations in the Desert and Syria were too 

 much interrupted and irregular to be of any scientific 

 value, and I, therefore, gladly avail myself of the table 

 kindly furnished me by my friend Mr. Hubbard, whose 

 attainments in physical science are of the highest order. 

 He had no self-registering thermometer, but took obser- 

 vations with an ordinary instrument with sufficient fre- 

 quency to give the extremes of temperature with a close 

 approximation to accuracy. 



The table for Upper Egypt and Nubia is intended to 

 exhibit at one view the daily maxima and minima of tem- 

 perature (according to Fahrenheit's scale), the mean of 

 the monthly maxima and minima, the monthly mean 

 and the average range; the force and direstion of the 

 Avind, the state of the weather with regard to clearness, 

 haziness, dryness, fog, &c. The temperature in the sun 

 is also given as compared with that in the shade, and that 

 of the water of the Nile on the same day and in the same 



