-SS8 Intelligence and Miscellaneous Articles. 



so that the hours of observation will in such cases be 6 a.m., 9 a.m., 

 3 p.m., 9 p.m. and midnight. 



To individuals who cannot command these hours, it is recom- 

 mended that observations should be made as near them as possible ; 

 'these will still be valuable, although not to so great an extent as 

 those made at the regular hours. In these cases, however, it will 

 be absolutely necessary to substitute two readings for every one of 

 the regular hours omitted — one previous to, the other succeeding 

 the hour so omitted ; and these should, if possible, include an equal 

 interval both before and after such hour. In all cases the exact hour 

 and minute of mean time at the place of observation should be in- 

 serted in its appropriate column in the form for recording the obser- 

 vations. 



At the regular hours of observation, or any others that the ob- 

 server may fix upon, in accordance with the foregoing instructions, 

 it will be necessary to observe, — 



1st. The barometer, with its attached thermometer, and enter in 

 the form the actual height observed with the temperature of the mer- 

 cury. 



2nd. The external and dry thermometer. 

 3rd. The wet bulb thermometer. 



These observations are particularly essential in order to separate 

 the pressure of the vapour from the aggregate pressure, as measured 

 by the mercurial column. 



4th. The direction and force of the wind. 



These are important to determine the connexion between the un- 

 dulatory and molecular motion of the wave. 



5th. The character of the weather at the times of observation ; 

 "which may be recorded by Capt. Beaufort's symbols. 



It is proposed to commence the observations on the 1st of October 

 next, and continue them daily, until the end of November, unless it 

 should be found that at that time the wave is not completed, in which 

 case it will be requisite to continue them a few days longer. 



It will be necessary on returning the form (to be forwarded to ob- 

 servers) when filled, to accompany it with the following data for re- 

 duction. A blank is left for this purpose on the back of the form. 



The geographical co-ordinates of the place of observation, viz. 

 latitude and longitude. 



The altitude of the cistern of the barometer above the level of the 

 sea, exactly, if not, as near as it can be obtained. 

 The internal diameter of the tube of the barometer. 

 The capacity, neutral point, and temperature. 

 These are usually engraved on the instrument. 

 If the coefficients of the diurnal and annual oscillations have been 

 determined for the place of observation, include them. 



Those sets of observations which may be reduced by the observers 

 should be accompanied with the original observations, and a refer- 

 ence to the tables used in their reduction, also the data above men- 

 tioned. 



