SCIENCE OF COMMON THINGS. 13 



Attraction of gravitation. Illustrations of gravitation. 



jj differ in size, but also drops of the same fluid, to 

 the 'extent of a third, from different parts of the lip of 

 the same vessel. 



69 Why is it difficult to pour water from a vessel which has not a pro- 

 jecting lip ? 



Because, in consequence of the attraction between 

 the water and the sides of the vessel, the fluid has a 

 tendency to run down along the inclined outside of the 

 vessel, and not at once to fall perpendicularly. 



7*O | What is the attraction of gravitation ? 



W<$ apply the term "gravity," or the "attraction 

 of gravitation," to that tendency which every particle 

 of matter in the universe has to approach all other 

 matter. Terrestrial gravitation is the attraction of a 

 body towards the centre of the earth. 



T'l In what respect does the attraction of gravitation differ from all other 

 attractive forces ? 



Because it is the common property of all bodies ; 

 since everything to which we can attach the idea of 

 materiality is aftected more or less by gravitation. 



7*3 Why does an appk loosened from the tree fall to the ground? 



Because the earth attracts or draws it to itself. 



7*3 Since all bodies are attracted towards the earth, how does it happen 

 that all smoke and some other forms of matter display the contrary pheno- 

 menon of ascending from it ? 



Because the smoke is lighter than the air, bulk for 

 bulk, and floats upon it. It is unable to advance, how- 

 ever, in the most minute degree, without displacing or 

 thrusting downward portions of the atmosphere equal 

 to its own bulk. 



7*4: Why does a cork pressed beneath the water rise and float on the 

 turf ace ? 



Because the cork is lighter than an equal bulk of 

 water, and is pressed up and sustained by it in the 

 same manner that the particles of smoke are sustained 

 by the particles of air. 



7*5 Why does a balloon rise in the air ? 



Because it is filled with a gas which is lighter, bulk 

 for bulk, than the air. 



