5§ THE WOMBAT. 



not more than twenty-five were left. The observations were 

 to be made daily, in conjunction with the recording of the 

 thermometer readings, weather and wind ; and books for 

 entering the observations were supplied. The work, though 

 exacting, soon became interesting, and one wondered that so 

 much could be seen and read upon the face of the sky. 



Roughly speaking, clouds may be divided into fine 

 weather and wet weather clouds — separate and globular 

 masses seen in fine weather and widely extended masses in 

 wet weather. Again they may be divided into upper, inter- 

 mediate and lower clouds. Of the upper clouds, whose 

 average altitude is 9,000 metres — 10,000 yards — we have 

 cirrus, detached, delicate, fibrous-looking masses, taking the 

 form of feathers and generally white in colour, sometimes- 

 arranged in belts across the sky, and, by an effect of per- 

 spective, seeming to converge at opposite points of the 

 horizon. To the upper clouds also belong the cirro-stratus, a 

 thin, whitish sheet, at times completely covering the sky, and 

 often producing halos round the sun and moon. It is by the 

 observation of these upper clouds that weather forecasts are 

 made, the nature and direction of the impending change being 

 dependent on the form, position, and direction of the cirrus 

 stripes. Roughly speaking, all places where these cross the 

 zenith lie in the track of the coming depression, the quarter 

 whence it comes depending upon the point where the stripes 

 appear to meet. The storm of 25/11/97 was clearly foretold 

 by a cirrus bank of very remarkable appearance lying across 

 the north-east horizon. 



Of intermediate clouds we have cirro-cumulus, alto- 

 cumulus, and alto-stratus. Cirro-cumulus consists ol small 

 globular masses without shadows, or having very slight 

 shadows arranged in groups or lines. 



Alto-cumulus consists of large globular masses (white or 

 greyish), often so closely packed that their edges appear 

 confused. 



Alto-stratus is a thick sheet of a grey or bluish colour, 

 showing a brilliant patch in the vicinity of the sun and moon. 

 This cloud goes through all the forms of cirro-stratus, but, 

 by measurements made at Upsala, its altitude has been 

 shown to be only half as great. 



Of lower clouds we have strato -cumulus and nimbus. 



Strato -cumulus consists of large globular masses or rolls 

 of dark cloud frequently covering the whole sky, especially in 

 winter, and giving it a wavy appearance. These clouds are, 

 as a rule, not very thick, patches of blue sky being often 

 visible through them. They may be distinguished from 

 nimbus by the fact that they do not bring rain. 



