OF THE ATMOSPHERIC TEMPERATURE.. 



173 



by their g^g , t'j- , ^ . . . . part respectively. Inversely, if vi^e wish to compare 

 computed monthly means with observed means, the respective multipliers are 



. 7t . 27t . 37t 



smj2 sin^ sin^ 



~^ 27t ' 37t 



l2 12 12 



In the case of incomplete monthly means, one or more being wanting, the func- 

 tion may still be employed by first finding, by interpolation, graphical or analytical, 

 values for the terms omitted, and obtaining first an approximate, and by a second 

 or third (if necessary) application an exact expression for T. For the supposition 

 of one month being omitted in the observations or y^ in the values, yiy^Vs • • • Vw, 

 wanting, Mr. Bravais gives the formula • — 



2/o = f (2/i + 2/5 + y? + 2/ii) + T (2/2 — 2/3 — 2/4 + 2/6 — 2/8 — 2/o + 2/io) 

 + r l/3 (2/1 — 2/5 — 2/7 + 2/ii) 

 The expressions for two or more adjacent ordinates are too complicated, and of 

 too little use to be inserted here. 



In connection with the use of the periodic function, a table giving the value of 

 Q for each day (noon) is herewith appended.^ 



' Table, as given by 



Mr. De 



Forest 



— 





















Day. 



Jan. 



Feb. 



Mar. 



Apr. 



May. 



June. 



July. 



Au 



g- 



Sept. 



Oct. 



Nov. 



Dec. 



I 



o°3o' 



31° 3' 



58°S3' 



89°26' 



119° 1' 



I49°34' 



179° 8' 



209°4i' 



240=15' 



269=49' 



300°22' 



329=56' 



2 



I 29 



32 2 



59 52 



90 26 



120 



150 



33 



180 7 



210 



40 



241 14 



270 48 



301 21 



330 55 



3 



2 28 



33 I 



60 51 



91 25 



120 59 



151 



32 



iSi 6 



211 



40 



242 13 



271 47 



302 20 



331 55 



4 



3 27 



34 



61 51 



92 24 



121 58 



152 



31 



182 5 



212 



39 



243 12 



272 46 



303 20 



332 54 



5 



4 26 



34 59 



62 50 



93 23 



122 57 



153 



30 



183 5 



213 



38 



244 II 



273 45 



304 19 



333 53 



6 



5 25 



35 59 



63 49 



94 22 



123 56 



154 30 



184 4 



214 



37 



245 10 



274 44 



305 18 



334 52 



7 



6 24 



36 58 



64 48 



95 21 



124 55 



155 



29 



185 3 



215 



36 



246 9 



275 44 



306 17 



335 51 



8 



7 24 



37 57 



65 47 



96 20 



125 55 



156 



28 



1S6 2 



216 



35 



247 9 



276 43 



307 16 



336 50 



9 



8 23 



38 56 



66 46 



97 19 



126 54 



157 



27 



187 I 



217 



34 



248 8 



277 42 



308 15 



337 49 



lO 



9 22 



39 55 



67 45 



98 19 



127 53 



158 



26 



1S8 



218 



34 



249 7 



27841 



309 14 



338 49 



II 



10 21 



40 54 



68 44 



99 '8 



128 52 



159 



25 



188 59 



219 



33 



250 6 



279 40 



310 13 



339 48 



12 



II 20 



41 53 



69 44 



100 17 



129 51 



160 



24 



189 59 



220 



32 



251 5 



280 39 



3" 13 



340 47 



13 



12 19 



42 53 



70 43 



lOI 16 



130 50 



161 



24 



190 58 



221 



31 



252 4 



281 38 



312 12 



341 46 



14 



13 18 



43 52 



71 42 



102 IS 



131 49 



162 



23 



191 57 



222 



30 



253 3 



282 38 



313 II 



342 45 



15 



14 18 



44 51 



72 41 



103 14 



132 48 



"63 



22 



192 56 



223 



29 



254 3 



283 37 



314 10 



343 44 



i6 



15 17 



45 50 



73 40 



104 13 



133 48 



164 



21 



193 55 



224 



28 



255 2 



284 36 



31s 9 



344 43 



17 



16 16 



46 49 



74 39 



los 13 



134 47 



165 



20 



194 54 



225 



28 



256 I 



285 35 



316 8 



345 42 



i8 



17 15 



47 48 



75 38 



106 12 



135 46 



166 



19 



195 53 



226 



27 



257 



286 34 



317 7 



346 42 



«9 



18 14 



48 47 



7638 



107 II 



136 45 



167 



18 



195 53 



227 



26 



257 59 



2S7 33 



318 7 



347 41 



20 



19 13 



49 47 



77 37 



108 10 



137 44 



168 



17 



197 52 



228 



25 



258 58 



288 32 



319 6 



348 40 



21 



20 12 



50 46 



7836 



109 9 



138 43 



169 



17 



198 51 



229 



24 



259 57 



289 32 



320 5 



349 39 



22 



21 II 



51 45 



79 35 



no 8 



139 42 



170 



16 



199 so 



230 



23 



260 57 



290 31 



321 4 



350 38 



23 



22 11 



52 44 



80 34 



III 7 



140 42 



171 



15 



200 49 



231 



22 



261 56 



291 30 



322 3 



351 37 



24 



23 10 



53 43 



81 33 



112 7 



141 41 



172 



14 



201 48 



232 



22 



262 55 



292 29 



323 2 



352 36 



25 



24 9 



54 42 



82 32 



lis 6 



142 40 



173 



13 



202 47 



233 



21 



263 54 



293 28 



324 1 



353 36 



26 



25 8 



55 41 



83 32 



114 5 



143 39 



174 



12 



203 46 



234 



20 



264 53 



294 27 



325 I 



354 35 



27 



26 7 



56 40 



84 31 



IIS 4 



144 38 



J75 



II 



204 46 



23s 



'9 



265 52 



295 26 



326 



355 34 



28 



27 6 



57 40 



85 30 



116 3 



■45 37 



176 



II 



205 45 



236 



18 



266 51 



296 26 



326 59 



356 33 



29 



28 5 



58 16 



85 29 



117 2 



146 -,6 



177 



10 



206 44 



237 



17 



267 51 



297 25 



327 58 



357 32 



3° 



29 5 





87 28 



118 I 



147 36 



178 



9 



207 43 



238 



16 



268 50 



298 24 



328 57 



358 31 



31 



30 4 





88 27 





148 35 



j^^^^ 





208 42 



239 



15 





299 23 





359 30 



The arc from the beginning of the year to the middle of each calendar month is found in the above 

 table opposite the 16th for months of 31 days, and by subtracting 30', for months of 30 days; the 

 arc to the middle of February is 44° 28'. 



