CONVERSION OP LINEAR MEASURES. xlix 



Example : 



To find the duration of sunshine, May i8, 1892, in latitude 49° 30' North. 

 From the Nautical Almanac, 8=19° 43' N. 



From the table, with 8 =19° 43' iV and <^ = 49°3o'. the duration of 

 sunshine is found to be 15^ 31'". 



TABLE 62. 



TABLE 62. Declination of the sun for the year 1894. 



This table is an auxiliary to Table 61, and gives the declination of the 

 sun for every third day of the year 1894. These declinations may be used 

 as approximate values for the corresponding dates of other years when the 

 exact declination can not readily be obtained. Thus, in the preceding 

 example, the declination for May 18 may be taken as approximately the 

 same as that for the same date in 1894, viz. 19° 37'. 



RELATIVE INTENSITY OF SOLAR RADIATION AT DIFFERENT LATITUDES 

 FOR DIFFERENT SEASONS OF THE YEAR. 



TABLE 63. Mean vertical intensity for 24 hours of solar radiation f and 

 the solar constant A in terms of the vieaii solar constayit A^. 



This table is that of Prof. Wm. Ferrel, published in the Anmial Report 

 of the Chief Signal Officer, 1885, Part 2, and in Professional Papers of the 

 Signal Service, No. 14, where the formulae and constants will be found. 



It gives the mean vertical intensity for 24 hours of solar radiation / in 

 terms of the mean solar constant A^ for each tenth parallel of latitude of the 

 northern hemisphere, and for the first and sixteenth day of each month ; 

 also the values of the solar constant A in terms oi A^, and the angular 

 motion of the sun in longitude for the given dates. 



CONVERSION OF LINEAR MEASURES. 



The relation here adopted between the metre and the English measures 

 of length is that used and officially authorized by the U. S. Bureau of 

 Weights and Measures, viz : 



I metre = 39.3700 inches. 



TABLE 64. 



Table 64. Inches into ■millimetres. 



The argument is given for every hundredth of an inch up to 32.00 

 inches, and the tabular values are given to hundredths of a millimetre. A 

 table of proportional parts for thousandths of an inch is added on each page. 



Example : 



To convert 24.362 inches to millimetres. 

 The table gives (p. 184) 



(24.36 + 0.02) inches= (618.75 + 0.05 mm.) = 6i8.8omm. 



