192 MR. J. BAXENDELL ON ATMOSPHERIC OZONE. 



Observations at the Radcliffe Observatory, Oxford. 



At the end of the volume of ^ Radcliffe Observations ' 

 for 1864 a table is given showing the " Mean Monthly- 

 Quantities of OzonCj as determined by Schonbein's Ozono- 

 meter in a period of Ten Years^ commencing with 1856.^^ 

 The observations had been made twice daily, at 10^ p.m. 

 and 10^ A.M.; and the mean monthly values are as fol- 

 lows : — 



10^ P.M. and 



lO*^ P.M. lO^'A.M. lo'^A.M. 



January 2-5 2-8 2*65 



February 2*9 37 3*30 



March 36 3*9 375 



April 4-3 4-5 4-40 



May 5-3 5-8 5-55 



June 4*4 4*8 4*60 



July 3'6 4*1 3*85 



August 4-0 4*5 4-25 



September 3*6 3-9 375 



October 2*8 3*2 3*00 



November 1*9 2*0 1*95 



December 2*1 2*5 2*30 



The curve No. 2 in the annexed 

 diagram is a projection of the 

 numbers in the last column, while 

 curve No. I is a projection of 

 Mr. Mackereth^s results. 



It will be seen that the prin- 

 cipal maximum and principal 

 minimum both occur one month later at Oxford than at 

 Eccles, and that a secondary maximum occurs at both 

 stations in the month of August. 



It is stated at the foot of the table in the ^ Radcliffe 

 Observations ' that the following facts are deducible from 

 the above numbers : — 



I . That the greatest quantity of ozone generally occurs 

 in the spring, and the least quantity in October and No- 

 vember. 



