540 



METEOROLOGY. 



rent. Hence we learn that ascending' currents 

 favor the formation of clouds and the fall of 

 rain, while descending currents contribute to 

 dry weather. Finally, the introduction of the 

 mechanical theory of heat into the study of 

 phenomena has thrown light on all questions 

 relating to evaporation and the condensation 

 of vapors in the form of rain. The synoptical 

 method, which permits a representation of the 

 meteorological condition of a whole country at 

 the same moment, the recognition of the im- 

 portance of the distribution of pressures as a 

 factor of atmospheric movements, and the les- 

 sons of thermodynamics, are the bases of the 

 meteorological science of the day. 



Temperature. The determination of the pre- 

 cise rate at which the temperature diminishes 

 in passing to the upper regions of the atmos- 

 phere has been found to be very difficult. Me- 

 teorologists have therefore generally directed 

 their efforts to the determination of the rela- 

 tion between pressure and temperature. Meen- 

 deleef deduces, from the experiments made by 

 Glaisher in balloon ascensions, that the temper- 

 ature at the limit of the atmosphere is about 

 36 0. Woeikof computes, from the observa- 

 tions of the Russian aeronaut, Rykachef, a mean 

 temperature of 42 C. 



The essential fact brought out in the tem- 

 perature observations by Messrs. Mill and Mor- 

 rison, of the Firth of Forth, is that the win- 

 ter condition of the Firth is one of uniformly 

 rising temperature from the river to the sea, 

 and from the surface of the water to the bot- 

 tom ; while the summer condition is one of 

 uniformly falling temperature from river to sea, 

 and from surface to bottom. The temperature 

 of the river Thurso, in the north of Scotland, 

 has been observed at the mouth and at a point 

 twelve miles inland. The river appeared to 

 respond rapidly to changes of temperature. 

 During the greater part of the winter the water 

 kept close to the freezing-point, though never 

 actually freezing, except at the margin ; while 

 the sea had been uniformly from 10 to 5 

 Fahr. warmer than the river, and its tempera- 

 ture had never been below 40 Fahr. 



Mr. J. Morrison made monthly observations 

 on the distribution of temperature in Loch Lo- 

 mond and Loch Katrine, Scotland, from De- 

 cember, 1885, to March, 1886. At the point of 

 deepest soundings in Lake Lomond the water 

 was each month of uniform temperature from 

 surface to bottom. In the deepest sounding 

 on Loch Katrine a similar distribution was 

 met with till February, when the point of 

 maximum density was 'obtained. Uniformity 

 still prevailed in March down to seventy fath- 

 oms. In April the temperature distribution 

 usually found in spring had set in in both 

 lakes, the surface being warmest, the bottom 

 coldest, and the temperature falling more and 

 more slowly with increase of depth. It was 

 remarked that the warmth of the bottom layer 

 increased monthly during the spring months 

 over the deepest part of both lakes a rise 



which was evidently due to some drainage 

 or oozing causing mixture. In both lakes the 

 temperature becomes uniform along the whole 

 length about the 4th of April. Mr. Morrison 

 made similar observations in the Firth of 

 Clyde in April and June, 1886. In April a 

 deep layer of uniform temperature was over- 

 laid by a layer of temperature rising serially to 

 the surface. In June the layer of varying 

 temperature had thickened to about twenty 

 fathoms, while the deep temperatures were 

 different in different parts of the field of ob- 

 servation, according, apparently, as they were 

 exposed to the influence of currents from 

 without. 



The winter of 1885-'86 was abnormally cold 

 in the British Islands. According to Mr. C. 

 Harding's paper on the subject, in the Royal 

 Meteorological Society, the greater deficiency 

 of temperature occurred in the weeks ending 

 January 25, March 1, 8, and 15. The tem- 

 perature was below the average for the season 

 over the whole kingdom in October, January, 

 February, and March, while in some quarters 

 it was also below the average in December, 

 and in the northwest of England and over a 

 great part of the north of Scotland in every one 

 of the six months. The lowest shade tempera- 

 ture was 2 at Braemar on the 19th of January 

 and at Alston on the 7th of March. From the 

 beginning of January to the middle of March 

 there was almost continuous frost, and during 

 this period it froze for upward of sixty nights 

 at many places. At Greenwich it froze ou 

 twenty-eight consecutive days, from February 

 14 to March 18, or for a longer period than 

 had been recorded in fifty years. The excess- 

 ive cold weather experienced at the beginning 

 of March, and the unusual frequency of snow- 

 fall, were peculiar features of the season. 

 Skating was afforded in Regent's Park in each 

 of the four months, from December to March, 

 for the first time since 1830, and for the fourt 

 time in March. The temperature of the wat 

 in the Thames at Deptford was, on the m< 

 slightly in excess of that of the air. Observf 

 tions at several stations in England showed 

 that at one foot below the surface the greatest 

 cold was reached during the first seventeen 

 days of March ; the mean was generally about 

 2 in excess of the mean air-temperature. The 

 temperature of the soil at two feet was gener- 

 ally about 2 in excess of that at one foot. 



The logs of ships traversing the North At- 

 lantic show that abnormal conditions extended 

 also a considerable distance to the westward. 

 They show a decided tendency to a low ba- 

 rometer, during the early months of 1886, in 

 the locality where a high barometer generally 

 prevails, and to the north of this low barome- 

 ter strong and persistent easterly winds were 

 experienced. 



An analysis of the temperatures of Scotland 

 during the past 122 years by Mr. Buchanan 

 shows that the last fifteen years have been dis- 

 tinguished by the coldest consecutive sum- 





