Description of the Tables. Ixiii 



The seventh column gives the readings, in inches and decimals, of the Obser- 

 vatory rain-gauge, made at noon. 



The eighth column contains the maximum pressure of wind on a square foot 

 of surface which has occurred since the previous observation, No. 95. 



The ninth column contains the greatest pressure which occurs within 10 minutes 

 at the time of observation ; titled the present pressure ; this is sometimes higher 

 than the maximum previously recorded. 



The tenth column gives the point of the compass from which the surface-wind 

 blows, as observed on the vane-dial. 



The eleventh column gives the points of the compass from which the clouds 

 move, observed as described No. 97 ; when there are more motions than one ob- 

 served, the motion of the lowest stratum of clouds is placed first, that is to say, next 

 to the motion of the surface-wind in the tenth column ; the motion of the next higher 

 stratum is separated from that of the lower stratum by a colon (:), and so with those 

 higher still. Thus, July 12*^ 18"^, while the motion of the surface-current was pro- 

 bably from WSW., the lowest stratum of clouds moved from NW., the next higher 

 from NNW., and the highest clouds from SE. by S. 



The twelfth column gives the estimated quantity of the sky covered with clouds, 

 or the estimated surface of clouds compared with that of the whole hemisphere, the 

 latter being 10. 



109. The page opposite to these columns contains the species of clouds and 

 general observations on the state of the sky or weather, as observed immediately 

 after the observations of the meteorological instruments. The clouds whose motions 

 have been defined are placed first, commencing with the lowest, and when several 

 motions have been observed the strata are separated, as the directions are in the 

 eleventh column, by colons (:) ; thus, in the above example, July 12^ 18"^. Scud 

 moved from NW., cirro-cumulous scud from NNW., and cirri from SE. by S. 

 When the directions in which any clouds move have not been determined, these are 

 separated from the others by a cross h— ; in the previous example there was a thick 

 mass of cirrous haze and cumulo-strati to E., whose motion was undetermined. The 

 initial of the observer is given last ; and as the same person makes the magnetical 

 and meteorological observations, the initials serve for the magnetical observations 

 at the same hours. 



Term-Day and Extra Meteorological Observations, pages 200 — 217. 



110. These observations are made, during the magnetical term-days, at the 

 solstices and equinoxes,* and on other occasions. 



* The observations at the solstices and equinoxes were forwarded by Sir Thomas Brisbane to 

 M. QuETELET of Brussels, and have appeared in his collection of " Observations des Phenomenes Perio- 

 diques," Memoires de I'Academie Royale de Bruxelles. 



