RUM. PARASITIC CLOUDS. 477 



case no fall of rain took place in Rum, from the absence 

 of some unknown condition in the land or in the vapour ; 

 but it is plain that with some modifications of that con- 

 dition, this island might have been deluged in rain, (as 

 it often is) while its more humble neighbours were enjoy- 

 ing a cloudless sky. 



There is so much difficulty in explaining the general 

 causes of these appearances, and the theory of clouds and 

 rain is as yet so imperfect, that there is no reason to 

 be surprised if we are. unable to account for the different 

 effects which these two mountains, whose summits are 

 not perhaps half a mile asunder, produced on the same 

 atmospheric 'current. It has appeared that the one exer- 

 cised, together with its precipitating power, a constant 

 repulsion, maintaining the condensed vapour at an inva- 

 riable distance ; while the other, although in its immediate 

 vicinity, combined together with that power, the property 

 of attracting the vapour into close contact. In attributing 

 these discordant actions to electrical influence, it is pro- 

 bable that the true cause is assigned ; although we must 

 at the same time equally confess our imperfect knowledge 

 of the mode in which that cause operates in producing 

 these effects, as in the production of those numerous and 

 important meteorological phenomena which also appear to 

 depend on it. It may perhaps be suggested <hat the pre- 

 cipitation was merely the effect of a difference of tempera- 

 ture between the land and the atmosphere ; and that the 

 different action of the two mountains in attracting and 

 repelling, arose from their different electrical conditions ; 

 conditions which we are acquainted with in the electricities 

 of approximate bodies as they occur in our confined expe- 

 riments. 



Under such a climate, and with a soil of almost the 

 worst qualities, it is not surprising that there is but little 

 cultivation in Rum. Even that little is too much, as far 

 at least as relates to white crops ; to the culture of which 

 the stormy nature and asperity of the climate are pecu- 



