INTENSITY OF SUN'S HEAT AND LIGHT. 



57 



landscape fades on the sight, and the stars begin to be visible. The end of civil 

 twilight marks the time at which some city corporations in Europe are said to have 

 made regulations for lighting the street lamps. 



In conclusion, without entering into further details, the connection of solar heat 

 and light has enabled us to exhibit, by the same formulae and curves, the intensities 

 of both in common. Indeed so close is the analogy that even the monthly height 

 of the mercurial column, which shows the temperature, indicates generally the 

 average intensity of sunlight in that locality. 





Ha 



/ Days, 



or Semi- 



Diurnal Arcs, in 



Hie Northern Hemisphere. 







1853. 



Lsit. 0°. 



Lat. 10°. 



Lat. 20°. 



Lat. 30°. 



Lat. 40°. 



Lat. 50°. 



Lat. 60°: 



Lat. 70°. 



Lat, 80°. 



Lat. 90°. 





h. m. 



1). m. 



h. m. 



h. m. 



h. m. 



h. m. 



h. m. 



h. ra. 



h. m. 



h. m. 



Jan. 1 



6 00 



5 43 



5 24 



5 03 



4 37 



3 58 



2 51 



00 



00 ' 



00 



" 16 



6 00 



5 44 



5 28 



5 09 



4 45 



4 11 



3 13 



00 



00 



00 



" 31 



6 00 



5 48 



5 35 



5 18 



5 00 



4 33 



3 49 



2 04 



00 



00 



Feb. 15 



6 00 



5 51 



5 41 



5 30 



5 17 



4 58 



4 29 



3 29 



00 



00 



Mar. 2 



6 00 



5 55 



5 50 



5 44 



5 36 



5 26 



5 10 



4 40 



3 00 



00 



" 17 



6 00 



5 59 



5 58 



5 57 



5 56 



5 54 



5 51 



5 46 



5 32 



00 



April 1 



6 00 



6 04 



6 07 



6 11 



6 16 



6 22 



6 32 



6 51 



7 49 



12 00 



" 16 



6 00 



6 01 



6 15 



6 24 



6 35 



6 50 



7 12 



7 59 



12 00 



12 00 



May 1 



6 00 



6 11 



6 22 



6 36 



6 53 



7 15 



7 52 



9 12 



12 00 



12 00 



" 16 



6 00 



6 14 



6 29 



6 46 



7 08 



7 38 



8 28 



10 50 



12 00 



12 00 



" 31 



6 00 



6 16 



6 34 



6 54 



7 19 



7 55 



8 58 



12 00 



12 00 



12 00 



June 15 



6 00 



6 18 



6 36 



6 58 



7 25 



8 04 



9 14 



12 00 



12 00 



12 00 



July 1 



6 00 



6 17 



6 36 



6 57 



7 23 



8 02 



9 09 



12 00 



12 00 



12 00 



" 16 



6 00 



6 16 



6 33 



6 52 



7 17 



7 51 



8 51 



12 00 



12 00 



12 00 



" 31 



6 00 



6 13 



6 28 



6 44 



7 04 



7 32 



8 19 



10 20 



12 00 



12 00 



Aug. 15 



6 00 



6 10 



6 21 



6 33 



6 48 



7 09 



7 42 



8 53 



12 00 



12 00 



" 30 



6 00 



6 06 



6 13 



6 21 



6 31 



6 44 



7 04 



7 43 



10 14 



12 00 



Sept. 14 



6 00 



6 02 



6 05 



6 08 



6 11 



6 16 



6 23 



6 37 



7 18 



12 00 



" 29 



6 00 



5 59 



5 57 



5 54 



5 52 



5 48 



5 43 



5 33 



5 03 



00 



Oct. 14 



6 00 



5 54 



5 48 



5 41 



5 32 



5 20 



5 02 



4 27 



2 20 



00 



" 29 



6 00 



5 51 



5 40 



5 28 



5 13 



4 53 



4 22 



3 14 



00 



00 



Nov. 13 



6 00 



5 47 



" 5 33 



5 17 



4 57 



4 29 



3 43 



1 46 



00 



00 



" 28 



6 00 



5 44 



5 27 



5 08 



4 43 



4 09 



3 09 



00 



00 



00 



Dec. 13 



6 00 



5 43 



5 24 



5 03 



4 37 



3 57 



2 49 



00 



00 



00 





Increase of 



the Half Day at Sunrise, 



or Sunset, by Refraction. 







1853. 



Lat. 0°. 



Lat. 10°. 



Lat. 20°. 



Lat. 30°. 



Lat. 40°. 



Lat. 50°. 



Lat. 60°. 



Lat 70°. 



Lat. 80°. 



Lat. 90°. 





m. 



m. 



m. 



ra. 



ra. 



111. 



m. 



ra. 



m. 



m. 



January 



2.5 



2.5 



2.6 



2.8 



3.3 



4.4 



6.7 



0.00 



0.00 



0.00 



February 



2.4 



2.4 



2.5 



2.7 



3.1 



3.8 



5.1 



9.0 



0.00 



0.00 



March 



2.3 



2.3 



2.5 



2.7 



3.0 



3.8 



4.6 



7.0 



14.0 



0.00 



April 



2.3 



2.4 



2.5 



2.8 



3.2 



3.8 



5.0 



8.0 



0.00 



0.00 



May 



2.4 



2.5 



2.6 



3.2 



3.5 



4.5 



6.1 



22.0 



0.00 



0.00 



June 



2.5 



2.6 



2.8 



3.1 



3.7 



4.9 



7.6 



0.00 



0.00 



0.00 



July 



2.5 



2.5 



2.7 



3.0 



3.5 



4.7 



6.7 



0.00 



0.00 



0.00 



August 



2.4 



2.5 



2.5 



2.8 



3.2 



4.0 



5.2 



9.7 



0.00 



0.00 



September 



2.3 



2.4 



2.5 



2.7 



3.1 



3.7 



4.6 



7.0 



14.7 



0.00 



October 



2.3 



2.4 



2.5 



2.7 



3.1 



37 



4.9 



7.5 



24.3 



0.00 



November 



2.4 



2.5 



2.6 



2.8 



3.2 



3.9 



5.9 



16.3 



0.00 



0.00 



December 



2.5 



2.5 



2.7 



2.9 



3.5 



4.6 



7.5 



0.00 



0.00 



0.0,0 



