34 ACCIDENTAL METEORIC PHENOMENA. 



It should be stated if the wind blows in a continuous manner 

 or in squalls, and what is its force. 



If there should be one or more moments of calm, the hour and 

 duration will be indicated. 



Great care must be taken at each observation to note also the 

 direction of the different layers of clouds, which will very often 

 be found different from that of the wind below, for the whole 

 duration of the storm. 



Tlie clouds. Are there certain forms of clouds which an- 

 nounce the approach of a storm ? It is necessary, in this con- 

 nection, to watch the formation of the cirrus, the cirro-cumulus, 

 cirro-stratus, their arrangement in parallel lines, their course, and 

 their directions. Note the quarter of the sky first covered with 

 clouds ; the moment when it is entirely covered ; if there are 

 later clear spots or not ; the moment when the sky clears off. 



The rain Note the hour at which the rain or the snow begins 

 and ends ; measure the quantity fallen while the storm lasts. 



ACCIDENTAL METEORIC PHENOMENA. 



These will be entered in the tables, in the place reserved for 

 this purpose on the opposite side of the sheet. If the space is 

 not sufficient for the description to be given, the phenomenon 

 should be simply noted, and reference made to a separate account 

 for details. Thus: 



The solar and lunar haloes that is, the colored circles some- 

 times observed round the sun and moon. Distinguish the small 

 ones, the ring of which measures only a few degrees, from the 

 large or real haloes, the ring of which has a diameter of about 

 forty-four degrees. It must be stated whether they are connected 

 with other circles, as is sometimes the case. Care must be taken 

 not to mistake a part of a grand halo for a rainbow. Note 

 whether these appearances are, or are not, ordinarily followed 

 by rain. 



The Parhelia and Paraselenes (mock-suns and moons). De- 

 scribe exactly their forms and the state of the heavens at the 

 moment of their appearance. 



Rainbows, simple or double. 



An extraordinary redness of the sky, either in the morning or 



