IV 



CONTENTS. 



Page. 

 METEOROLOGICAL OBSERVATIONS 



TOPOGRAPHY OF THE SANTIAGO BASIN xxx 



CHANGE OF CLIMATE ............... xxxii 



TABLK HI- Hours of rain at Santiago de Chile xxxiii 



Other antecedent observations .............. xxxiii 



TABLE IV. Meteorological summary for 1849 xxxiv 



TABLE V. Temperature, clouds, and rain for 1849 sxxiv 



Probable increase in the annual number of rains . . . . . . . . . . xxxv 



INSTRUMENTS AND OBSERVATIONS 



Description of the barometer .............. xxxvi 



TABLE VI. Corrections applied to the readings of the barometer, to reduce the observations to 32 Fahrenheit . . . xxxviii 



Description of the thermometers .............. xxxviii 



TABLE VII. Equivalents centrigrade and Fahrenheit's thermometer scales ........ xxxix 



Mode of observing the direction and force of the wind .......... xl 



Description of the rain gauge .............. xl 



Clouds ................. xl 



Personnel ................. xl 



ABSTRACTS OF AND COMMENTS UPON THE HOURLY OBSERVATIONS OF TERM-DAYS 



TABLE VIII. Atmospheric pressure at every hour of the day . . . . . . . ' . . . xli 



TABLE IX. Excess of the atmospheric pressure at every hour above the adopted mean for the month ..... xlii 



TABLE X. Temperature of the air at every hour of the day . . . . . . . . . . xliii 



TABLE XI. Excess of the temperature at every hour above the mean monthly temperature . '"'. ' . . . . xliv 



TABLE XII. Temperature of evaporation at every hour of the day ......... xliv 



TABLE XIII. Excess of the temperature of the air at every hour of the day above the temperature of evaporation at the same hour xlv 



TABLE XIV. Mean direction of the wind at every hour of the day ......... xlvi 



TABLE XV. Mean force of the wind at every hour of tlie day . . . . . . . . . . xlvii 



TABLE XVI. Mean portion of the sky obscured at every hour of the day . . ..... xlviii 



MAGNETICAL OBSERVATIONS ............... 1 



Absolute declinations at SANTIAGO DE CHILE . . . . '""I"' ' '. " '. - . . . . 3 



Diurnal changes of the declination at Santiago . . . . . . . . . . . 4-18 



Declinometer and unifilar observations at short intervals on the first of each month ...... 19-26 



Variations of the horizontal force on the first of each month ......... 27-31 



Observations to determine th absolute horizontal force . . . . . . . . . . 32-117 



Calculations of the absolute horizontal force at SANTIAGO . . " . . . .''"*''. . . 120 



Calculations of the absolute horizontal force at LA CANDELARIA . . . . . . . . . 121 



Calculations of the absolute horizontal force at CALDERA . . . . . . . . . . 121 



Calculations of the absolute horizontal force at VALPARAISO . . . . . . . . . 121 



Calculations of the absolute horizontal force at HERRADURA . . . . . . . . . 121 



Calculations of the absolute horizontal force at WASHINGTON, D. C. . . . . . . . . 121 



Results of the observations of the magnetic inclination at SANTIAGO DE CHILE ....... 124 



at LA CANDELARIA, CopiAp6, CALDERA, VALPARAISO, and HERRADURA 129 



Observations of the north pole of the inclinometer on term-days ......... 1 30 



Magnetic term-day observations at WASHINGTON, D. C., and in CALIFORNIA, 1851-1855, communicated by Prof. A, 



D. Bache, Superintendent U. S. Coast Survey .....;.;.. 131-156 



Corresponding changes of the diurnal magnetic declination at MARBURG, (in Hesse,) by Dr. C. L. Gerling . . 157 



Letter from Dr. Gerling, describing the instrument and mode of observation ... . . . . 159 



Diurnal changes of the declination on term-days . . .- . . -. * . . . . 161-185 



Changes of the declination at short intervals on the first day of each month . . . *. . 186-187 

 METEOROLOGICAL OBSERVATIONS 



Tri-hourly observations a* SANTIAGO DE CHILE, from November, 1849, to September, 1852 . , . . 191-355 



from day observationi ....... 356-370 



