24 SCIENCE PRIMERS. [MATERIAL 



17. The Meaning of Weight. 



Let us next consider the property of weight. We 

 say that anything has weight when, on trying to lift it 

 from the ground, or on holding it in the hand, we have 

 a feeling of effort. Or again, if anything which is sup- 

 ported at a certain height above the ground, falls when 

 the support is taken away, we say that it has weight. 

 Now the ground merely means the surface of the earth ; 

 and, as all bodies which possess weight fall directly to- 

 wards the surface of the earth when they are not kept 

 away from it by some support, we may say that all 

 bodies which have weight tend to fall in this way. And 

 it does not matter on what part of the surface of the 

 earth you make the experiment. Rain consists of 

 drops of water, and it does not matter whether we 

 watch a shower in calm weather here, or in New 

 Zealand ; the drops fall perpendicularly towards the 

 ground. But we know that the earth is a globe and 

 that New Zealand is at our antipodes, or on the 

 opposite side of the globe to England. Hence if 

 two showers are falling at the same time, one in New 

 Zealand and one here the drops must be falling in 

 opposite directions, towards one another ; that is, 

 towards the centre of the earth which lies between 

 them. In fact, all bodies which have weight tend to 

 fall towards the centre of the earth that is to say 

 they fall in this way if there is nothing to prevent 

 them ; and when we speak of weight we mean this 

 tendency to fall. To call anything heavy, is the 

 same as saying that we fully expect that, if there is 

 nothing to support it, it will fall to the ground ; or 

 that if we support it ourselves we shall be conscious 

 of effort. 



