488 



METEOROLOGY. 



whole subject as unworthy of serious treat- 

 ment. For instance, atmospheric tides due to 

 the moon's attraction must exist, although they 

 are generally obliterated by disturbances due to 

 other causes. Sir John Herschel's opinion, 

 that the full moon has a tendency to clear the 

 sky is, apparently, borne out by certain facts, 

 and is supported by the experiments of Melloni 

 and others, which go to show that moonlight 

 contains a minute proportion of dark heat-rays, 

 the effect of which may be in a certain meas- 

 ure to cause the dispersion of the clouds. The 

 lunar halo is an old sign of rainy weather, 

 which is confirmed in a large proportion of 

 instances. Capt. 0. Von Bermann, of the Hy- 

 drographic Office of Pola, dicussing the same 

 question, reaches the conclusion that, although 

 the moon has an influence on the weather, it is 

 too infinitesimal, compared with other influ- 

 ences, to be appreciable. 



Experiments by Prof. E. TV. Morley led him 

 to conclude that a diminished amount of oxy- 

 gen in the atmosphere coincides with a baromet- 

 ric maximum, through the descending current 

 which, in anti-cyclones, brings downward air 

 deficient in oxygen from higher elevations. 

 This is contrary to the conclusion of M. Folly, 

 and has been disputed by Max Schumann 

 as not satisfactory, because tho descend- 

 ing air in the region of an anti-cyclone does 

 not proceed from those elevations in which a 

 less amount of oxygen may be expected. 

 There is a certain altitude, indeed, Schumann 

 observes : " and this is certainly greater than 

 that at which these atmospheric processes take 

 place, the combined effect of which is called 

 ' weather,' up to which the amount of oxygen 

 may be regarded as invariable. The air, found 

 by Mr. Morley to contain less oxygen, proceeds 

 from elevations inferior to those, because the 

 air is not sucked down from strata above that 

 limit, but only takes a circular path induced in 

 a region of disturbed air by the ascending cur- 

 rent. In consequence of this circular path, 

 which is easily understood by thinking of a 

 ring on a horizontal plain in the center of 

 which the air ascends and is sucked over the 

 upper edge of the ring down along the outer 

 surface and under the lower edge back to the 

 center of the ring, the air descending on a re- 

 gion of high barometrical pressure proceeds at 

 all events only from those elevations in which 

 the amount of oxygen may be regarded as in- 

 variable." 



The doctrine, formerly prevalent among me- 

 teorologists, that watery vapor m the air is 

 more active in absorbing and returning ter- 

 restrial radiation than the pure gases of the 

 atmosphere, has been reviewed by W. M. Davis, 

 who concludes, with Magnus and others, that 

 watery vapor as such that is, water in the 

 gaseous state, possesses very little absorptive 

 power. Still, meteorological observation leaves 

 no question that nocturnal cooling is greater on 

 clear, dry nights than on clear, damp nights. 

 This is because, on the damp nights, we have 



vapor in a state of incipient temporary con- 

 densation to deal with, and instead of uniformly 

 diffused gas, invisible water droplets, which 

 reflect or radiate back the heat that is radiated 

 to them from the earth. 



Temperature. Concerning conditions that 

 may affect temperature in the New England 

 States, the Bulletin of the New England Me- 

 teorological Society mentions as worthy of 

 note in the reports for September, 1887, that 

 the maximum temperatures of the 7th of the 

 month were the productof southerly and south- 

 westerly cyclonic winds, importing warmth 

 from the Southern States; while the minimum 

 temperatures of the 24th and 27th were of lo- 

 cal origin by nocturnal radiation into the clear, 

 anti-cyclonic sky. Under such conditions the 

 maxima are rather uniform over the greater 

 part of New England except Maine, while the 

 minima are strongly influenced by topography, 

 and are much lower in valleys than on hills. 



The results obtained by Mr. John Murray, of 

 the " Challenger " Commission, and himself, in 

 their observations on the temperature of the 

 western lakes and lochs of Scotland, are thus 

 summed up by Dr. II. E. Mill: The eastern 

 fringe of the North Atlantic Ocean, brings be- 

 tween the western islands water at a uniform 

 temperature of 46. An equal temperature 

 prevails on the surface, except in the vicinity 

 of land, where it is higher. In nearly land- 

 locked sea-lochs and basins the temperature of 

 the mass of water is determined by the config- 

 uration, and varies from 47'5 to 43 '8, accord- 

 ing to certain definite laws. Fresh-water lakes 

 that are shallow have a temperature of about 

 45; those that are deep are colder, their tem- 

 peratures varying from 43 to 41, while they 

 show hardly any difference between surface 

 and bottom. 



Some details respecting the freezing of the 

 rivers and lakes of Russia are given in a pam- 

 phlet published by M. Nikacheff. The times of 

 the earlier frosts vary according to the char- 

 acter of the season in tho western and south- 

 ern parts of the empire, but are more uniform 

 toward the north and east. The rst freezing 

 usually takes place about the 1st of September, 

 in a branch of the Kolima. Other rivers fol- 

 low in due succession, till the Kuban, the last 

 to be frozen, is closed about the 18th of Janu- 

 ary, to open again about the 15th of February. 

 From that time the thawing advances toward 

 the north and east till the end of June, when 

 the great rivers, the Yenesei and the Lena, are 

 open to their mouths, and in July only the 

 rivers of the Taimyr peninsula are partly 

 clogged with ice. The lines of synchronal 

 freezing and thawing trend, like the isothermal 

 lines, as a rule, from west-northwest to east- 

 southeast. In the spring-time, or when the 

 temperature has risen above the freezing-point, 

 the smaller rivers thaw out first, then tho 

 larger rivers, next the canals, and finally the 

 lakes. In freezing, the canals are first, next 

 the rivers, small and large, and the lakes last. 



