36 



S. A. Hill — Observations of the Sotar Thermometer. [1^0. 1, 



cases, I have made a graphic representation of the logarithms of the 

 observed radiation on a scale the abscissae of which represented the 

 values of e ; and any observation which fell wide of the straight line 

 indicated by the formula has been rejected. 



Proceeding in this way, I have arrived at the following probable 

 mean values of the solar radiation undiminished by absorption, and of 

 the absorbing power of the atmosphere for vertical rays. The latter are 

 the values of (1 — ^) when ;p is defined as above. 



Table III. — Mean Values of the Constant of Solar Madiation in Degrees 

 of the Blaok-hulh Thermometer. 









March 



April. 



May 



June. 



Sept. 



Oct. 



Nov. 



Dec. 



Mean of 



Year. 



Jan. Feb. 



all 

 months. 



Eight 

 months.* 



1877 ... 



76-1, 78-2 



72-7 



73-3 



80^4 



86-6 



77-6 



79-8 



91-1 



85-5 



80-1 



79-6 



1878 ... 



78^5 



90-8 



88-3 



85-0 



92-4 



95-8 



? 



85-4 



84-6 



79-2 



86-7 



85^5 



1879 ... 



76-7 



77-6 



80^1 



92-7 



99-2 



85-9 



771 



74-6 



71-2 



69-4 



80^4 



80^2 



1880 ... 



73-2 



78-6 



83-3 



75-9 



80-6 



P 



80-7 



791 



68-3 



70-7 



76-7 



76-2 



1881 ... 



72-4 



74-0 



78^1 



72^2 



85-7 



77^5 



73-9 



73^6 



67-6 



71-7 



74-7 



74-4 



1882 ... 



75-2 



79^5 



78-8 j 



81-9 



78-8 



73-4 



70-6 



68-8 



67-5 



71-3 



74^6 



75^2 



1883 ... 



74-4 



73-0 



76-6 



80-9 



77-8 



79-7 



74-9 



74-9 



76-1 



75-7 



76-4 



76-2 



1884 ... 



74-7 



74-0 



74-6 



82-5 



82-0 



77-6 



77-6 



73-8 



78-7 



76-4 



77-2 



771 



Mean 



V5. 



78-2 



79-0 



80^6 



84-6 



82-4 



76-1 



76-2 



75-6 75^0 



78-3 



78-0 



Table IV. — Coefficients of Atmospheric Absorption for Vertical Rays. 



Year. 



Jan. 



Feb. 



March 



April. 



May. 



June. 



Sept. 



Oct. 



Nov. 



Dec. 



1877 



1878 



1879 



1880 



1881 



1882 



1883 



1884 



•175 



•260 

 •212 



•179 

 •201 

 •199 



•222 

 •241 



•194 

 •264 

 •199 

 •211 

 •194 

 •218 

 •224 

 •243 



•188 

 •269 

 •226 

 •317 

 •230 

 •258 

 •278 

 •245 



•216 

 •266 

 •324 

 •265 

 •255 

 •295 

 •316 

 •251 



•294 

 •354 

 •390 

 •306 

 •360 

 •302 

 •306 

 •277 



•342 

 •407 

 •358 



P 

 •377 

 •311 

 •319 

 •324 



•272 



? 

 •312 

 •256 

 •213 

 •231 

 •277 

 •272 



•269 

 •274 

 •232 

 •259 

 •233 

 •240 

 •235 

 •368 



•251 



•268 

 •251 

 •191 



•187 

 •175 

 •228 

 •223 

 •274 



•255 

 •230 

 •201 

 •160 

 •205 

 •224 

 •216 

 •267 



Mean 



•211 



•218 



•251 



•279 



•326 



•333 



•262 



•225 



•220 



* June and September being left out. 



