566 Mr. A. R. McLeod on 



From these figures it is seen that the formula 



s 



tan D = — + 



s 2R /( ' 



(54) 



gives the range to within 1 part in 400, when li — l km., 

 tor values of <£ not exceeding §§° 48' ; while for h=2, 3, or 

 4 km. the results are better still. The errors are least for 

 7( = 4 km. They are negative up to 3 km., and positive- 

 above 4 km . 



, . Fig-. 6. 



S3 tp 



An inspection of the values o£ Q in Table VII. shows that 

 the values of Q contained in Table Till, are more suitable- 



