METEOROLOGY. 



COMMUNICATION FROM A. FENDLER. 



COLONIA TOVAR, VENEZUELA, SoUTH AMERICA, 



August 5, 1856. 



Dear Sir : I sailed from Philadelphia on the 5th of May, and 

 arrived at Laguayra three weeks after. Colonia Tovar I reached on 

 the 7th of June, and commenced my meteorological observations on 

 the 10th. The barometer and the dry and wet bulb thermometers, 

 which by your kindness I received from Mr. Green, I have brought 

 home safe and in good order. 



Accompanying this I send you two registers of meteorological ob- 

 servations of the month of June and July, 1856 ; and here I have to 

 make the following remarks : 



1. As I am very much interested in the results of the observations, 

 I need not say that I pay the most particular care and attention to 

 the condition of the instruments, as well as to the nicety in taking 

 observations and in noting them down. 



2. The column under the head of " Barometer height reduced to 

 freezing point/' I could not fill up for want of the necessary tables. 



3. By comparing my old thermometer, which is one of the more 

 common kinds, marked " T. Barry, London," with the Smithsonian 

 dry bulb thermometer, I found that the former is from one and a half 

 to five degrees too high ; so that I was obliged to use the dry bulb of 

 the psychrometer also as thermometer in the open air. The wet bulb 

 was therefore exposed to the open air also. According to the first 

 principles of evaporation it is, however, evident that the more rapid 

 the motion of air is which touches the wet bulb the more energetic 

 will be the evaporation of the water contained in the wet linen, and 

 the lower will the mercury sink. This I found to be confirmed by 

 every breeze, and even the ligtitest breath of wind that happened to 

 strike the wet bulb at the time I took observations. I therefore regard 

 all observations with the psychrometer, that are not taken in a calm 

 atmosphere, or in an atmosphere the velocity of which at the time of 

 observation is known, as of little value. 



As I had no other standard thermometer besides the dry and wet 

 bulb, I can give the psychrometrical observations only, with the re- 

 mark that they are worth just as much as all other such observations 

 made in the open air without regard to the currents of the atmo- 

 sphere. In future I shall try to shelter the wet bulb against the 

 influence of wind at the time of observation, 



4. As I have no rain gage I can only put down the time of be- 

 ginning and ending of rain. 



5. With regard to clouds I may say, that the higher clovids are 

 mostly hidden from view by the masses of lower clouds, so that the 

 course of the former can very seldom be ascertained in the rainy 

 season, and, when seen, there are several strata, one above the other. 

 Instead of the higher clouds, I have carefully noticed and put down 



