FORESTRY. 219 



793. A joist of yellow pine, 2" x 12" x 14', will sup- 

 port what distributed load? If 2" x 8" x 14'? 



794. A beam of yellow pine, 10 feet long and 12 inches 

 deep is to carry two tons at the middle point, what 

 must be the breadth? How might this beam be built up 

 if 2" x 12" x 10' planks be used? 



795. What is the safe working distributed load that 

 may be applied to a beam of hickory 2" x 2" x 10'? 



796. Of soft maple 2" x 2" x 10'? 



797. Of yellow pine 2" x 2" x 10'? 2" x 4" x 10'? 

 2" x6" xlO'? 



798. Of white oak 2" x 2" x 10'? Red oak? Yellow 

 birch? 



799. A piece of yellow pine, 2" x 2" x 20', supports 

 from its middle point a certain weight. What should be 

 the length of a piece of hickory of the same breadth and 

 thickness, that the same weight may be supported ? 



800. A red oak beam, 8" x 8" x 20', supports a weight 

 equal to its safe working load. If a yellow pine timber of 

 same length is substituted, what breadth will be required, 

 that the same weight may be carried? 



801. In planning a barn yellow pine timbers 12 inches 

 broad and 20 feet long are to be used as beams, .each tim- 

 ber being called upon to sustain 15 tons at the middle 

 point. What depth of timbers will be required ? 



