to the Antarctic Regions. 201 



of the observations made at these institutions by the scientific au- 

 thorities wlio will be entrusted vv^ith the execution of this task. 



The suggestions which the Council wish to offer will relate, 1st, 

 to the times of observation ; 2ndly, to the situation of the instru- 

 ments to be observed ; 3rdly, to the correction of the observations ; 

 4thly, to a form of registry, which may place many of the results in 

 a striking point of view, and facilitate comparisons. 



1. Barometers. 



Times of observation. — The purposes of meteorological observa- 

 tions would be most perfectly and most expeditiously obtained by 

 hourly observations throughout the year ; but as at present such a 

 course of unremitting labour cannot be hoped for, it is necessary to 

 select periods, at longer intervals, calculated to embrace the extremes 

 of the periodical oscillations to which the pressure of the atmosphere 

 is subject, and to ensure that uniformity of system at different sta- 

 tions on which the value of such observations so much depends. 

 It is probable that the hours of 3 a.m., 9 a.m., 3 p.m., and 9 p.m., 

 nearly coincide with the daily maxima and minima of the barometric 

 column at the level of the sea, over a large portion of the globe ; and 

 it is desirable that as extensive a comparison as possible should be 

 instituted at these hours. 



It is not, however, too much to expect that in regular observatories 

 hourly observations should be made, for 24< hours, once in every 

 month ; and when this cannot be effected, \\. is of the utmost im- 

 portance that they should be made at least four times in the year, 

 namely, at the summer and winter solstices, and at the spring and 

 autumn equinoxes. One of the results of these hourly observations 

 would probably be the indication of the exact times of the daily 

 maxima and minima of pressure at different stations, which, if not 

 found to coincide with the hours provisionally adopted, might ulti- 

 mately be substituted for them under future directions. 



Hourly observations at the equinoxes and solstices have been al- 

 ready instituted at numerous points both of Europe and America, 

 at the suggestion of Sir John Herschel, whose directions should be 

 strictly attended to. They are as follows : — 



The days fi:.ed upon for these observations are the 21st of March, 

 the 21st of June, the 21st of September, and the 21st of December, 

 being those, or immediately adjoining to those, of the equinoxes and 

 solstices in which the solar influence is either stationary or in a state 

 of most rapid variation. But should any one of those IXst days fall 

 on Sunday, then it will he understood that the observations are to be 

 deferred till the next day, the '2,'2.nd. The observation at each station 

 should commence at 6 o'clock a.ai. of the appointed days, and ter- 

 minate at 6 A.M. of the days following, according to the usual reckon- 

 ing of time at the place. 



The commencement of each hour should be chosen, and every 

 such series of observations accompanied by a notice of the means 

 used to obtain the time, and, when practicable, by some observation 



