REPORT OP THE SECRETARY. 25 



Systematic representation of the daily fluctuation of the temperature, 



by means of a periodic function. 

 Analysis of the daily fluctuation. 

 Variability of the temperature at any hoar of the day from the normal 



value of that hour. 

 Section III. — The annual fluctuation of the temperature expressed in 



terms of a periodic function. 

 Table of computed annual fluctuation of the temperature at forty-six 



stations. 

 Discussion of the results for dates of mean annual values and for 



maxima and minima ; and annual range in connection with the geo- 

 graphical distribution of the stations. 

 Examination into alleged interruption in the regularity of the annual 



fluctuation at certain epochs, with tables of temperature of each day 



of the year, deduced from a series of years. 

 Investigation of the variability of the temperature of any one day in a 



series of years. 

 Inequality in the epoch of the minima and maxima of the annual 



fluctuation. 

 Tables of observed extremes of temperatures, arranged by months, for 



a selected number of stations. 

 Analysis of tabular results for greatest heat and greatest cold with 



regard to geographical distribution. 

 Extreme annual range of temperature and monthly absolute variability; 



exhibition of the law of annual distribution. 

 Tables of the mean annual temperature, principally in the United 



States, for a succession of years from the earliest records to the close 



of the year 1870. 

 Investigation of the secular variation of the annual mean temperature, 



and of the permanency of the climate. 

 Comparison of the secular variation of the temperature with the varia- 

 tions in the frequency of the solar spots. 

 Comparison of the secular variation in the temperature and rain-fall in 



the United States. 

 Comparison of the secular variation in the temperature with the aver- 

 age annual direction of the wind. 

 Range of variability in the secular variation of the annual temperature. 

 Secular variation in the annual minima and maxima, compared with tbe 



variation in the annual means. 



The tables in the first section contain the number and name of each 

 station, its latitude and longitude, its elevation above the sea, its mean 

 temperature for each month and for each season, and for the whole 

 year, the extent of the series, the observing hours, and the name of the 

 observer. In cases where observations were made at hours of the day dif- 

 fering from those of the general series, they were reduced to uniformity 

 by corrections derived from tables of observations made at each hour of 



