The paving should be hard and durable but not porous. A good 

 test for paving material let it be brick, clinker, asphalte, or concrete 

 is to take a portion of it, and after carefully weighing it, leave it in a 

 pail of water for 24 hours and then weigh again. It will be manifest 

 that the pavement which absorbs least will, cceteris paribus, make the 

 best floor ; but hardness and sufficient roughness, to prevent the horses 

 slipping, are seldom to be found in one article, and therefore the paving 

 bricks are usually made with grooved surfaces. 



