234 



meteorologists of various other countries, the first issue of results 

 appearing in a chart annexed to No. 512 of " Nature," where wUl 

 be found an article on the subject and on the objects kept in view.* 

 The chart in question, " condensed from 30 of these charts — one 

 for each day of the month — shows for one month, the lines of 

 mean pressure, mean temperature, and average wind direction on 

 land and sea, within the limits of civilisation, on the Northern 

 Hemisphere." Great hope is entertained that, as this work pro- 

 gresses and improves, and the reports of observations become more 

 and more carefully elaborated, it may be found possible to arrive 

 at generalisations "permitting the announcement of meteoric 

 changes for periods longer in advance than have been hitherto 

 practicable." 



Whether this is likely or not, these charts cannot but help us 

 to a better knowledge of the conditions ujaon which our weather 

 changes depend, far beyond anything attainable by isolated 

 observers working independently of each other. They may help 

 us to determine the law by which particular winds prevail at 

 particular seasons, as, on the other hand, the causes, which occa- 

 sion an interruption of those winds when they are irregular ; all 

 our states of weather being directly due to the influence of par- 

 ticular winds, as all our changes of weather are due to changes 

 of wind. 



The easterly, or speaking more jjroperly north easterly, winds 

 in this country, usually so constant in spring, and attaining their 

 maximum in April or Maj', are too well known to call for any 

 remark. But I have elsewhere stated t as the result of close 

 observation of these winds over a long term of years, that though, 

 normally, they prevail in the spring season far more than at other 

 times, this is not always the case ; and I have adduced instances 



* See "Nature," No. 512, Vol. 20, p. 381 ; Aug. 21, 1879. 



t See "Observations in Meteorology," p. 113. See also "Proceedings of 



Bath Field Club," Vol. 1., No. 3, p. 45. 



