130 



MR. JOSEPH BAXENDELL 



made with the second thermometer during the years 1859- 

 1864, more especially as in 1857 ^^^ readings of the first 

 thermometer were only to the nearest whole degree, and 

 in 1858 the month of November was omitted; and in order 

 to make six complete years, I have included the observa- 

 tions made with the third thermometer from the 17th Sep- 

 tember to the end of 1864. 



The following Table shows the mean monthly and annual 

 differences between the maximum temperature in the shade 

 and that in the sun during the six years 1 859-1 864, and 

 the monthly and annual means of the entire series : — 



January 



February 



March 



April 



May 



June 



July 



August 



September 



October 



November 



December 



Annual means. 



1859. 



7-3 

 io*9 

 11-7 

 lyz 

 15-0 

 1 6*0 

 17-8 

 i6'3 

 i6'3 

 ii'i 



12*4 



6-2 



12-85 



1860. 



57 

 1 1-5 



11*2 



i6-i 

 13-5 



12*3 

 12-8 



125 



II-8 

 8-7 

 8-4 

 4*9 



1078 



1861. 



57 



9-0 



io'4 



154 



i3'5 

 14-4 



I2'4 



15-1 

 141 



II'O 



7*9 

 6-0 



1862. 



4' 2 



6-8 



7-6 



11-6 



II-6 



10 I 



i3'4 



13-3 



12-5 



8-8 



8-2 



4*4 



1863. 



4-9 



9*2 

 IO'2 



11-8 



II-5 

 13*2 

 142 



12-5 

 12-8 



8-4 



5-4 

 3'3 



11-241 9-37 I 978 



1864. 



5-3 

 7-6 



9'4 

 11-3 



I2'3 



11-6 

 123 



14-5 

 14-8 



lO'O 



6-5 



2*2 



Monthly 

 means 



9-81 



5'5i 

 9-16 



10*08 



13-23 



12-90 



12-93 



13-81 



14-03 



13-71 



9-66 



8-00 



4-50 



A projection of the mean monthly values gives the curve 



in diagram A, from which it will 

 be seen that the maximum amount 

 of radiation occurs in August, or 

 about a month later than the time 

 of maximum temperature ; whilst 

 the minimum occurs in Decem- 

 ber, about a month earlier than 

 the time of minimum tempera- 

 ture. There is also a slight secondary maximum in April. 

 This curve, therefore, differs from that of any other ele- 



