MADE AT MARIETTA, OHIO. 43 



burg. This barometer is suspended twelve feet above the banks of the Ohio Hiver. 

 The instrument was read off three times a day, without, however, recording the 

 temperature of the mercury. We can, therefore, make but a very limited use of 

 these observations. Supposing the temperature of the room was not allowed to fall 

 below 62° Fah., and to show the same temperature as that of the external air in 

 the shade when above 62°, a corresponding reduction of the barometric readings to 

 the freezing point of water was applied. The observations were taken quite irregu- 

 larly, generally three times a day, often but once or twice a day, with occasional 

 omissions for a number of days. ■ " 



Table XIV contains the monthly extreme readings^ of the barometer (referred to 

 32° Fah.) expressed in inches. The hours of observation are 6, 2, 9 in summer, 

 and 7, 2, 9 in winter, with such exceptions as have been stated in the record of 

 temperatures. 



* The monthly extremes (and all other readings and means) published by Dr. Hildreth, in Silli- 

 man's Journal, are not reduced to the freezing point of water. , 



7 



