METEOROLOGICAL OBSERVATIONS. 329 



REFLECTION ON FOG. When people walk in a deep white 

 tog- by night with a lanthorn, if they will turn their backs to 

 the light, they will see their shades impressed on the fog in 

 rude gigantic proportions. This phenomenon seems not to 

 have been attended to, but implies the great density of the 

 meteor at that juncture. 



HONEY DEW. June 4, 1 783. Vast honey dews this week. 

 The reason of these seems to be, that, in hot days, the effluvia 

 of flowers are drawn up by a brisk evaporation, and then, in 

 the night, fall down with the dews, with which they are 

 entangled. 



This clammy substance is very grateful to bees, who gather 

 it with great assiduity ; but it is injurious to the trees on which 

 it happens to fall, by stopping the pores of the leaves. The 

 greatest quantity falls in still, close weather; because winds 

 disperse it, and copious dews dilute it, and prevent its ill effects. 

 It falls mostly in hazy, warm weather. * 



MORNING CLOUDS. After a bright night and vast dews, 

 the sky usually becomes cloudy by eleven or twelve o'clock in 

 the forenoon, and clear again towards the decline of the day. 

 The reason seems to be, that the dew drawn up by evaporation 

 occasions the clouds ; which, towards evening, being no longer 

 rendered buoyant by the warmth of the sun, melt away, and 

 fall down again in dews. If clouds are watched in a still, 

 warm evening, they will be seen to melt away, and disappear, f 



DRIPPING WEATHER AFTER DROUGHT. No one that has 

 not attended to such matters, and taken down remarks, can 

 be aware how much ten days dripping weather will influence 

 the growth of grass or corn after a severe dry season. This 

 present summer, 1776, yielded a remarkable instance ; for, till 



* Mr William Curtis has discovered honey dew to be the excrement 

 of the aphides ; and justly remarks, that it is not to be found on any plant 

 where these insects do not accompany it. These aphides bring forth 

 ninety young, according to the observations of Reaumur, so that, in five 

 generations, the produce from a single one would be five thousand nin 

 hundred and four millions, nine hundred thousand. ED. 



f* It may be useful to agriculturists to observe this small cloud, which 

 is rapid in its formation and dispersion. It appears in the mild weather 

 of spring, summer, and autumn. It is a small, delicately soft, thin, white, 

 curved cloud, formed upon the summit of those fine, heaped clouds, 

 termed comuli, which seem to tower up to a prodigious height. When 

 this little " storm cap " is seen, it is closely over the rounded summit, 

 like a white silken web. It disappears in a few seconds, and generally 

 reappears, and again suddenly sinks. When this happens, foul weather 

 is certain within twenty-four hours. ED. 



