92 THE NATURE STUDY COURSE. 



fleeces or bunches, cirro-cumulus, or flecked and speckled, and 

 then it gives the effect called ' a mackerel sky.' Cirrus clouds 

 consist chiefly of ice spicules. 



Great rounded cloud-heaps, like immense fleeces, with flat 

 bases are called cumulus clouds. To extensive cloud areas, 

 seeming to be made up of masses of banded cumuli, the name 

 stratus is applied. Nimbus is the cloud stratum from which 

 rain or snow is falling. 



It is not much trouble to collect a set of good pictures 

 showing typical cloud-effects. The continued, intelligent 

 observation of clouds, not to speak of its practical value, 

 affords a constantly increasing source of pleasure. 



Wind. — Only the suggestion is needed to get some boy in 

 the class to make a wind-vane. It may be nailed to a suitable 

 part of the school fence or set up on the wood-shed. It should 

 be distant enough from the school-house, if not on it, to avoid 

 the eddies caused by the wind's sweeping around corners. To 

 determine the direction of the wind, besides observing the 

 vane, pupils should be encouraged to notice the smoke as it 

 issues from house or factory chimneys. The angle of ascent 

 as well as direction of the smoke is important. 



In the absence of an anemometer, the velocity of the wind 

 may be approximated and described as calm, faint, gentle, 

 moderate, strong, violent. The terms — air, breeze, gale and 

 storm — with degrees indicated by adjectives, are used by 

 seamen to describe twelve grades of wind-velocity ranging 

 from calm to hurricane. 



Temperature. — A thermometer should be hung outside on a 

 shaded side of the building where the pupils who expect to be 

 asked to report the temperature may easily consult it. If the 

 school is possessed of only one thermometer, a monitor may be 

 appointed whose duty it is to hang the thermometer out during 

 the noon hour and bring it in when school is called. 



