FROST. 359 



(being unsupported) falls by its own 

 weight. 



Q. Why cannot BRICKLAYERS and PLASTER- 

 ERS work in FROSTY weather ? 



A. Because the bricks and plaster 

 would start from their position as soon 

 as the frost came and expanded the 

 mortar. 



Q. Why do BRICKLAYERS COVER their work 

 with STRAW in spring and 'autumn? 



A. Because straw is a non-conductor, 

 and prevents the mortar of their new 

 work from freezing during the cold 

 nights of spring and autumn. 



Q. Why are WATER-PIPES often covered with 

 STALL-LITTER in winter time ? 



A. Because straw (being a non-con- 

 ductor) prevents the water of the pipes 

 from freezing, and the pipes from 

 bursting. 



Q. Why are delicate TREES covered with 



STRAW in WINTER ? 



A. Because straw (being a non-con- 

 ductor) prevents the sap of the tree from 

 being frozen. 



Q. Can WATER be FBOZEN in any way BESIDES 

 by frosty weather ? 



