P. 3, Equation B, read “ — x#/1”’. 
RP. 43, line 17, for ““tané — — cos 2e” vead ““tane = — cot2e 
eA nline 235 ufOrvacotee ead: Mey. 
P. 47, line 2, read “‘ increasing to 7/2 for = 7”’. 
P. 57, line 8, for ‘“‘«” read ‘‘e”’. 
P. 65, line 31, for ‘‘ August ”’ read ‘‘ September ’’. 
ae) 
ERRATA. 
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. 69, line 22, after ‘400 km.” introduce *‘ it”. 
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