ox PHOTOGRAPHIC METEOROLOGY, 



5? 



The following tables show a comparison between the Exeter measure^ 

 ments and those made at Blue Hill and Upsala respectively : — 



Mean Altitudes in Metres. 



In making such a compai'ison there are many difficulties, for the 

 different types of cloud so merge into each other that unless the figures, 

 are known to relate positively to clouds resembling a certain type picture 

 any agreement can only be general. 



It will be seen that the maximum values at Exeter exceed those of 

 the American and Swedish observations in every case except that of the 

 base of cumulus. It should be noted, however, that several of these 

 maxima occurred on one day (June 12, 1896). If that one day had been 

 omitted, the maxima for cirrus and cirro-stratus would be only about 

 1,000 metres greater than the Blue Hill values. 



