56: 



SCIENTIFIC NEWS. 



[June 15, lESS. 



THE COLOURS OF TWILIGHT. 



pROF. CONSTANTINI ROVELLI has recently pub- 

 ■ lished, in the Revue Scientifiqiie hidustriellc, a study 

 upon the colours exhibited at twilight, according to the 

 state of the air. 



Red and orange tints predominate when the air is dry. 

 On the contrary, yellow, and especially green, charac- 

 terises air charged with vesicular vapour. 



Prof. Rovelli studies the colourations of the air and 

 their successive modifications in various cases and in the 

 various parts of the crepuscular region in measure as 

 the sun disappears from the horizon. He likewise 

 studies the Same phenomena at the advent of " aurora 

 with rosy fingers," and from them draws conclusions 

 based upon the theory of the colours of the solar spec- 

 trum. Observation has already shown that the warmest 

 colours of the spectrum predominate during a. period of 

 fine weather, while a yellow tint, followed by a greenish 

 twilight, is the index of great humidity. 



On another hand, we may consider the atmosphere as 

 formed of two strata, the lower of which contains clouds 

 and dust, and the upper of which is more transparent. 

 These two strata, as regards their refrangibility and 

 absorption, behave differently in the presence of the rays 

 that traverse them. From this Prof. Rovelli concludes 

 that the crepuscular green is the precursor of rain, and, 

 on the contrary, that a rosy twilight announces fine 

 weather, according to the saying, " Rosso di sera; buon 

 tempo spera." Let us compare with this adage the one 

 current in Provence : " Roudge de matin, ploou sii lou 

 vesin " — i.e., " red in the morning, rain is approaching." 



BLUE MILK. 



'T'HE " blue milk" in question is not that well-known 

 fluid retailed by some milkmen, and owing its 

 heavenly tint to a careful removal of the cream and a 

 liberal addition of water. The Gazctti Agricok describes 

 a morbid change which sometimes occurs in unadulter- 

 ated milk under conditions not fully determined. Such 

 milks display sometimes a yellow colour, sometimes a 

 red, but most frequently a blue, owing apparently to the 

 presence of a multitude of living beings. When first 

 drawn the milk has nothing peculiar in its appearance. 

 But after exposure to the air for about twelve hours 

 there appear round blue spots of different sizes which 

 gradually extend. The blue colouration of milk some- 

 times becomes a very serious evil, not confined to single 

 farms, but extending over entire districts, as it has been 

 observed in Normand}', Artois, Holstein, and elsewhere. 

 This affection is most common from the beginning of 

 summer to the end of autumn. Such milk is not merely 

 disgusting, but actually injurious, especially to children. 



The causes which foster the appearance of this mould 

 in milk are not fully known. Phthisical cows, ill-cared 

 for and fed on spoiled food, are more liable to this alter- 

 ation in their milk than such as are healthy and well 

 treated. 



The dirtiness of cowhouses, dairies, and milkpails 

 further promote (he infection. It is certain that if the 

 blueness of milk is due to a fungus all these conditions 

 must aid in its multiplication. However, it appears to 

 be demonstrated that "blue milk" is closely connected 

 "with a diseased state of the cow. 



It is probable, though not fully established, that it is a 

 cryptogamic infection of the udder. 



INEQUALITIES OF MEN. 



MLAPOUGE, of Montpelier, has recently delivered 

 • before the Faculty of Natural Sciences in that town 

 a series of lectures on inequalities among men, in the 

 course of which he said that the political dogma 

 of equality rests on hypotheses which are utterly 

 false. He distinguished four social types among 

 mankind : — (i) The initiators, who show mankind 

 the way into the region of the unknown, and who 

 go in front. Restless and daring, with an intelli- 

 gence which is at least equal to the average, men of this 

 type do not travel readily along beaten tracks. New 

 ideas are the breath of life to them. They spend their 

 lives in new creations ; they are often wrecked, but the 

 true genius represents the most perfect form of this' 

 type. (2) Men of spirit, of intelligence, who, possess- 

 ing no creative power themselves, yet carry out and per- 

 fect the ideas and discoveries of the first type, to which 

 they are really the complement. (3) Men who, with 

 much or little intelligence, can work only with others, 

 who mistrust every new idea not accepted by all the 

 others, but who seize it with avidity when their neigh- 

 bours adopt it. If intelligent these men are docile, but 

 they dislike every change in routine, and they represent 

 the dulness of the mass in the face of every reform. (4) 

 Men of this type are not fit to attain even the smallest 

 step in culture. Evidently every man cannot be classed 

 under one or other of these divisions. In human 

 societies clear lines of demarcation do not exist, but for 

 general purposes the distinction is sufficiently evident. 

 The superiority of a race or nation depends on the 

 greater or smaller number of men of the first two 

 classes. The race which is richest in the first type is the 

 blonde dolichocephalic, and this has been the case even 

 when the people among whom they lived were not of 

 this kind. In Egypt, Chaldea, Assyria, Persia, India, 

 and even in China men of this type ruled. In the 

 Greek and Roman world it was the same, and it is so 

 still. In our own day the rank of a nation corresponds 

 with the strength of the blonde dolichocephalic element. 

 The Gallic and Frank elements which made France great 

 were of this type, and it plays the same part in England, 

 Germanj', and America. Near these come the Semitic 

 and Mediterranean races, who had reached a high grade 

 of civilisation when the blonde dolichocephalic peoples 

 were still savages. The remainder of mankind must be 

 reckoned the passive races. The brachycephalic races of 

 Europe, the Celto-Slavs, rarely produce men of the first 

 intellectual type. In the social changes of recent years 

 brachycephalic men, who form the lower classes, have 

 been elevated and brought forward, and herein, the lec- 

 turer thought, lies the great danger of the future 

 deterioration of the French nation. The existence of 

 the superior blonde dolichocephalic type is threatened 

 by amalgamation with the dark brachycephalic and in- 

 ferior races. 



Height of Aerolites and Shooting Stars. — According 

 to M. Denning (Astronomie), the mean heights observed 

 for the latter class of bodies were 129 kilometres at the 

 beginning of their course, 108 in the middle, and 87 at 

 the end. The aerolites are at lower altitudes, respec- 

 tively, III, 79, and 48 kilometres. He calculates 

 accordingly that the shooting stars become ignited in the 

 earth's atmosphere, at a height greater than that of the 

 aerolites by 18,000 metres. 



