64 



Report S.A.A. Advancement of Science. 



Appendix III. 



Provisional Chart of Isobars. 



AUGUST. 



30 OS 



.50 /O 



30/0 



50 IS 



Correction for Gravity - "050. 

 „ „ Sea level + 'OIO. 



Buchan.—The trend of his isobars 30-14 and 30-15 agrees closely with the 

 above, but 30-15 lies where 30*14 is shown here. The rest of his 

 isobars are more parallel to a latitude than shown here. Over 

 the Transvaal pressure is from 30-10 in North to 30-16 in SE. 



5^^^~His isobars closely follow the above, pressure is from 3006 in 

 the NW to 30-09 in SE. At Pretoria it is 30-075 ins. 



Oc/.— His isobars lie from SW to NE across Transvaal, and pressure is 

 from 29-96 in NW to 29-99 in SE. At Pretoria it is 29-978 ins. 



