REPORT OF THE SECRETARY. 21 



than this, and might best be observed at the narrowing portion of the 

 extreme western end of the lake. 



The twelfth volume of Contributions will also contain the records 

 of meteorological observations made at Providence, by Prof. Caswell, 

 an account of which was given in the last report. This series of 

 observations occupies 179 of the largest quarto pages which can be 

 introduced into the volumes of the Smithsonian Contributions. They 

 comprise a record of the barometer and thermometer made three times 

 a day, the direction and force of the wind, and the face of the sky for 

 the same period ; also, the depth of rain, together with a column of 

 general remarks on casual phenomena. The series is terminated by a 

 number of general tables — the first giving the monthly and annual 

 mean height of the barometer during the whole term of years ; 

 the second, the monthly and annual mean height of barometer at 

 sunrise or 6 a. m., 1 or 2 p. m., and 10 p. m. ; third, monthly and 

 annual mean temperatures, deduced from the three observations daily; 

 fourth, monthly and annual mean temperatures at sunrise or 6 a. m., 

 1 or 2 p. m., and 10 p. m. ; fifth, monthly and annual maximum and 

 minimum temperatures and range ; sixth, the number of days in each 

 month in which the prevailing winds came from each of the four quar- 

 ters of the horizon ; seventh, mean force of the wind at the different 

 hours of observation, and for the month and year ; eighth, mean 

 cloudiness of the sky at the different hours of observation, and the 

 mean for the month and the year ; ninth, monthly and annual number 

 of days in which the weather was clear, variable, or cloudy — on which 

 rain or snow fell ; the tenth, monthly and annual quantity of rain and 

 snow in inches. 



From the records themselves an account of the weather on any clay 

 for twenty-eight years past may be obtained. From the general tables 

 we can determine the connection of the variations of the barometer 

 with the changes of the weather, and deduce rules of practical import- 

 ance as well as of scientific interest. From the tables of the records of 

 the thermometer, we find that the mean temperature of Providence for 

 the whole time is 48° 19', and that during the twenty-eight years of 

 observation the oscillation on either side of this, with the exception of 

 four years, is within a single degree. 



The coldest year was that of 1836 ; the warmest was 1848. The 

 warmest January was that of 1843, and the coldest that of 1857, which 

 was also the coldest single month of the whole period. On an average, 

 the coldest month of the year is February ; the warmest month is July ; 

 and the warmest month of any summer of the whole period was August, 



