i 4 MADEIRA METEOROLOGIC. PART in. 



and Goldschmidt, have both of them written on the 

 climate, Dr. Mason's remains the classical work on that 

 climate's ruling feature. 



It was a posthumous publication, 1 a monument to his 

 name and labours erected out of the papers he had left 

 behind him, by his widow ; for he had meanwhile passed 

 away, in consumption, at the early age of twenty-seven 

 years. But so long as he lived, the fervour with which 

 he threw himself into his peculiar subject of the invisible 

 vapour of water permeating the hard atoms of the per- 

 manent gases of the atmosphere, just as a stream of 

 water transfuses itself among the pebbles of a gravel bed, 

 to use Dalton's simile, is indescribable. Dr. Mason 

 had, too, taken his own hygrometer with him to Madeira, 

 and forthwith observed it almost continuously by day 

 and by night during nearly two years. 



And what was his hygrometer ? It was what is now 

 generally know r n as the dry and wet bulb thermometer, 

 for showing the temperature of water evaporation. An 

 instrument too much undervalued then, and long since 

 then, by high science, as compared with any apparatus 

 for giving the still lower reading of the dew-point tem- 

 perature ; but which, though excellent if you can get it, 

 is often only to be reached by a lavish expenditure of 

 sulphuric ether a fluid not always procurable by 



1 By Title, Madeira : Its Climate and Meteorology, by J. A. Mason, M.D. 

 Published by John Churchill, London, 1850. 



