1889.3 Africa from Barometric Observations. 325 



It will be seen that a much greater apparent accuracy might have 

 been obtained by leaving out the observations at those places where 

 trustworthy independent means of ascertaining sea level do not exist, 

 as also by omitting some which are vitiated by obvious errors. The 

 real utility of the table would however have been thereby diminished, 

 as it is very instructive to contrast those errors which may fairly be 

 called legitimate, as they arise from the necessary imperfections of our 

 methods, and those which are illegitimate as arising from downright 

 blundering somewhere. 



