46 Mr. E. Gold : Relation between Periodic Variations of 



But 1/r is negligible compared with y and n is negligible 

 compared with yg/n, so that 





-(7 + *i)C a = 0, 



whence C 1 = C 2 =0 to the first approximation since 02 = 02=0 

 at the earth's surface. 



Thus r 2 is large compared with T] and is given approxi- 

 mately by 



7-T, -91 OE 



gr 2 = fcli sin - 9 ~s~~" • 



QZ 



Therefore the difference o£ phase between the variations of 

 temperature and pressure is 180° nearly. The following- 

 table gives the amplitudes and phases of the diurnal varia- 

 tions of temperature and pressure at different places. 



Place. 



Pressure. 



Temperature. 



A r 1 a r 



A x '. 



a x \ 



A _ A ' 



Ocean 



mm. 



358 0'15 



25 -62 



20 -39 



21 -52 

 360 -59 



37 -37 

 23 -34 



243 

 232 

 240 

 232 

 237 

 252 

 256 

 251 

 224 

 240 

 241 

 240 

 229 

 240 

 242 

 232 

 219 

 227 



°0. 



0-72 



2-8 



2-8 



2-9 



30 



40 



1-7 



2-9 



1-4 



40 



2-7 



3-2 



1-4 



30 



32 



5-4 



32 



2-8 



o 



115 

 153 

 140 

 149 

 123 

 145 

 127 

 128 

 98 

 144 

 128 

 146 

 139 

 105 

 145 

 105 

 128 

 109 

 128 

 143 





Trevandrum 



Manila 



Madras 





Juluit 



Ascension 



St, Helena 



Port-au-Prince... 



Am Gabun 



Singapore 



Loanda 



Dar-es-Salam 

 Bismarckburg ... 



Allahabad j 



Goalpara 



Greenwich ' 



Blue Hill ! 



19 



322 



24 



9 



26 



8 

 345 

 27 

 337 

 347 

 336 



•28 

 •17 

 •51 

 •73 



•53 



•85 

 •58 

 •55 

 •77 

 •85 

 •18 



... 



Boston 





The mean difference of phase is 130°, and the agreement 

 is perhaps as good as could be expected, considering the 

 variations in the diurnal pressure-wave which have been 



neglected. 



