Sir D. Brewster on the Law of Daily Temperature. 351 



Hours. Observed temperatures. Calculated. Difference. 



7h. 39 m. p.m. Mean 4?46 4>46 0-00 



8 47-18 47-18 000 



9 46-30 46-48 0-18 



10 45-77 45-87 +010 



11 45-38 45-36 —0-02 



12 45-07 44-95 —012 



1 a.m. 44-81 44-64 -017 



2 4464 44.43 —0-21 



3 44-44 44-31 —0-13 

 3 40 Min. 44-29 44-29 000 



4 44-33 44-44 +011 



5 44-59 44-53 —006 



6 45-20 4502 —0-18 



7 45-97 45-78 —019 



8 46-96 46-80 —016 



8 32 Mean 47-46 47*46 0-00 



9 47-90 48-14 +0-24 



10 49-00 49-38 +0-38 



11 49-98 50-33 +0-35 



12 50-75 50-98 +0-23 



1 p.m. 51-24 51-32 +008 

 140 Max. 51-39 51-39 000 



2 51-36 51-38 +002 



3 51-09 51-32 +0-23 



4 50-48 50-62 +0-12 



5 49-74 5017 +043 



6 48-94 49-33 +0-39 



7 47-98 48-27 * +0-29 

 7 39 Mean 47'46 47'46 0-00 



From this very instructive table it is obvious that from eight 

 o'clock at night till eight in the morning, that is during the 

 average night, when the obstruction of the sun's rays by adja- 

 cent hills can have no effect upon the thermometer, the devia- 

 tions from the parabola are very small, and less than those at 

 Leith ; whereas, from eight in the morning till eight at night, 

 that is during the average day, the deviations are considerable 

 when compared with those at Leith, arising, doubtless, from 

 the obstruction of the sun's rays in particular azimuths. That 

 this is the cause of the deviations may be inferred from their 

 signs. During the night the deviations are negative, and during 

 the day positive', that is during the night the observed tem- 

 peratures are greater than the parabola makes them, owing to 

 the radiation of cold from the obstructed portions of the sky 

 being less than if it had not been obstructed ; whereas during 

 the day the deviations are large and negative, that is during 

 the day the hills have obstructed the sun's rays in particular 

 azimuths; and the observed temperatures are less than the 

 parabola makes them. 



These results were so important, that it became very desira- 

 ble to ascertain the relation of the Inverness daily curve to 



