26 Questions Jor Solution relating to Meteorology^ 



the utility of the observations we have proposed ; but the two 

 preceding must suffice. 



Rain in a -perfectly Clear Sky. — There are phenomena of an 

 extraordinary description, on which science possesses {ew obser- 

 vations ; for this reason, that those who have had the privilege 

 to witness them, avoid speaking of them from an apprehension 

 that they might be regarded as undiscerning visionaries. In the 

 number of these phenomena we may rank certain rains of the 

 equinoctial regions. 



Sometimes it rains between the tropics when the atmosphere 

 is perfectly pure, and the sky of the most beautiful azure ! The 

 drops are not very thick, but they are of larger size than the 

 rain-drops in our climates. The fact is certain ; we are assured 

 by M. Humboldt that he has observed the occurrence in the in- 

 terior of countries, and by Captain Beechey that he has wit- 

 nessed it in the open sea. With regard to the circumstances 

 on which such a singular precipitation of water can depend, we 

 are entirely ignorant of them. In Europe we sometimes see du- 

 ring the day, in calm and clear weather, small crystals of ice 

 falling gently from the air, their size increasing with every par- 

 ticle of humidity they congeal in their passage. Does not this 

 approximation put us in the way of obtaining the desired expla- 

 nation? Have not the large rain-drops been at first, in the 

 higher regions of the atmosphere, small particles of ice exces- 

 sively cold ; then have become, as they descended, large pieces 

 of ice by means of agglomeration ; and when lower still, been 

 melted into large drops of water ? It will be readily understood 

 that the only object with which these conjectures are brought 

 forward in this place, is to shew in what point of view the phe- 

 nomenon may be studied, and to stimulate our young travellers, 

 in particular, to observe carefully if, during these singular rains, 

 the region of the sky from which they fall present any traces of 

 halo. If such traces are perceived, however slight they may be, 

 the existence of crystals of ice in the higher regions of the air 

 will be demonstrated. 



In the present day there is scarcely any country where meteo- 

 rolosjists are not to be found, but it must be confessed that their 



