402 KANSAS CITY REVIEW OF SCIENCE. 



The great Michigan fire in September, 1881, might be brought forward as 

 evidence of extensive discoloration of the sky by smoke, then the query may be 

 raised : if smoke may thus discolor the sky, why not dust ? 



If one will refer to the Weather-Map for that date he will see that on that 

 day we had an area of low-barometer on a high line of latitude. The smoke 

 effect took place in the track and within the influence of this "Low," and no- 

 where else ; and it only lasted a few hours, in all about half a day. It did not 

 continue on around the world, west as well as east, and continue for months. 



We occasionally have a tornado. The dust raised from this source is local, 

 but at times it spreads over a great extent of territory Bnd fills the air with fine 

 dust, and dust that ought to remain in the air as long as any volcanic dust from 

 Java, and yet who ever heard of this dust for even one day producing a red sky? 

 As to the properties of dust, it will not, even under the most favorable circum- 

 stances, compare with water in the power of refraction ; as for its power of reflec- 

 tion it must be of very bright surface to produce much effect in this line. Water 

 will produce such effects ; the evidence thereof is daily before us ; we have but to 

 look at the clouds, at the ocean, and at the rainbow. 



In meteorology we have high and low-barometer; the one may be termed 

 the atmospheric-hill, the other the atmospheric valley. '-Low" or low-barom- 

 eter is the is the agent of the storm ; the centre to which the winds are gathered. 

 The clouds are being formed wherever there is heat and moisture ; as the clouds 

 are formed the winds carry them along towards "Low." On the surface of the 

 earth this movement is from the " High" to the " Low," the result is that there 

 is little moisture at " High/' but then it is impossible to remove all the moisture 

 from " High " and it is just the little, the fninimum, which remains that produces the 

 delicate pink or red sky. In the area of " High " there are few or no clouds pre- 

 sent — the sky is clear. The moisture present is so thin that we do not see it 

 when the sun-light is at right angles to the cloud stratum or moisture. It is not 

 until the Sun is below the horizon, when, as it were, we see through this thin 

 atmosphere edgewise, that the effect is produced; also in addition to this the Sun 

 shines up underneath this delicate cloud formation and illumines the under side 

 of it. This is well illustrated by a piece pi glass; hold it so the plate or pane is 

 perpendicular to the light and we see no color, turn it edgewise to the light and 

 we have quite a strong green color. We also see this same general effect in the 

 Moon, when it rises of a clear night, while at the horizon, when we see it through 

 the lower stratum of atmosphere, through the atmosphere edgewise, it appears to 

 be of a deep red color ; when it has ascended to mid-heaven, if it is a clear night 

 it is of a bright silver-white, yet it is the same Moon that at the horizon was a 

 deep red. The Moon has not changed, it is only the different atmosphere through 

 which it is seen that produces the effect. So there is no doubt as to the power 

 or property of water to produce this phenomenon. 



Those who have earnestly supported the dust theory have considered it con- 

 clusive that this red-sky phenomenon was seen in "foggy England," and yet a 

 little further on they say that the atmosphere was the while '' refnarkably free 



