316 Meteorological Observations at Hudson, Ohio. 



mean temperature of the place, yet with the assistance of the 

 hourly observations made at Philadelphia by Capt. Mordecai, we 

 may be able to determine it pretty satisfactorily. The diurnal 

 oscillation from 9 A. M. to 3 P. M. is nearly the same at both 

 places ; we may then without much fear of error, assume that the 

 excess of the 9 A. M. observations above the mean temperature is 

 also the same, viz. one degree. Subtract then one degree from 

 48^.6, and also 0°.2 for the zero error of the thermometer, we 

 have 47°. 4 for the mean temperature of Hudson. 



The same problem I have attempted to solve by means of the 

 temperature of wells. There are two deep wells in this vicinity 

 whose temperature I have frequently tried. The following are 

 the observations. 



It will be perceived that the temperature varies very little with 

 the season. Observations were therefore subsequently made 

 only twice a year, about the time of maximum and minimum. 



These observations present several remarkable circumstances. 

 One is, that the mean temperature of the well A should be for 

 each year exactly 1°.4 higher than B ; yet they are only twenty- 

 four rods distant from each other, are similarly exposed, are nearly 



