492 NATURE STUDY. 



is used with very small hole in bottom, through which 

 water may trickle very slowly, masses of needle-shaped 

 crystals may be formed projecting in from the sides. 



Place pan first examined out on window ledge, and 

 leave several hours until children can see that the crys- 

 tal needles have become wedged and joined together to 

 form the solid ice. Try to have children observe outdoors 

 or at home the appearance and formation of ice. 



After such observational study of ice crystals and ice, 

 even the little folks enjoy and appreciate the beauty of 

 portions of the selection from Lowell's "Vision of Sir 

 Launfal." 



Cannot the children see something of the formation, 

 growth, and beauty of the icicles ? An old pan or can, 

 perforated so that the water may escape from it slowly, 

 suspended outside the window on a cold day, may show 

 the little folks something of the formation of icicles, from 

 dripping water slowly congealing and constantly lengthen- 

 ing downward (or sometimes upward), and adding new 

 layers. This will not merely add to the children's appreci- 

 ation of common things, but may prepare for an under- 

 standing of the way Mother Nature decorates her under- 

 ground palaces in limestone caves with similar, but even 

 more beautiful forms, frozen in stone. 



Expansion of ice. Fill a bottle or other glass or earthen- 

 ware vessel with water, and place out on window ledge 

 over night, or place in the freezing mixture of pounded 

 ice and salt. The pressure of the ice crystals, all trying 

 to lengthen and thicken as they interlace, causes the ice to 

 expand, or "get bigger," as the children say, cracking the 

 vessel in which the water is, if it is not very strong, or 

 pushing up, as when water freezes in a strong pail. Apply 

 to bursting of pitchers, water-pipes, etc., in cold weather. 

 If the water is kept running, it is not so apt to freeze. 

 Why? 



