8 



The modulus of rupture for transverse stress is the stress at the 

 instant of rupture upon a unit of the section which is most remote 

 from the neutral axis on the side which first ruptures. 



The modulus of elasticity is a value which expresses the rela- 

 tion between the extension, compression, or other deformation of 

 a bar, and the force which produces the deformation. 



Resilience is a measure of the capacity of a material to resist 

 shock, and its value is equal to the amount of energy expended, or 

 the " work " performed in producing distortion or rupture. 



GENERAL DESCRIPTION OF THE WOODS. 



(I.) Carbon. Extraordinarily solid, equalled only by the Piedra 

 and the Quiebra-hacha. Is almost imperishable when used for 

 posts, and is supposed to be very good for railroad ties. The tree 

 attains a height of 30 feet, and measures 12 inches in diameter. 

 Is common in most of the wooded districts. The wood is of a very 

 fine grain, with peculiar dark streaks; very much like the 

 mahogany in appearance and in color, but heavier and much hand- 

 somer. Is easy of working, and turns very smoothly. 



(2.) Cedro (Cedar.) The wood, on account of its peculiar 

 properties, has found a place in all the markets abroad. In Nica- 

 ragua, it is found abundantly, and attains enormous sizes. Is used 

 extensively for furniture, frames, book cases, etc. It is even used 

 by the Indians for boats, which they work out entire from the 

 trunk of the tree. 



(3.) Chaperno. Dark red color, turns and planes very smoothly. 

 It has a fine grain and great strength and is susceptible of high 

 polish. It is used extensively for cross pieces of drawers and 

 tables. Is extremely durable. There are two varieties of this 

 wood, black and white, as they are called respectively. The tree 

 attains a height of forty feet. 



(4.) Chiquirin. Dark yellowish wood with a strong cedar 

 smell. Is heavy, fine grained and planes smoothly. Th,e tree 

 attains a height of thirty feet, and one foot in diameter. It has 

 various uses, is durable, and having odor is probably not subject 

 to attacks by insects. 



(5.) Cortes. Extremely heavy and very fine-grained, of a very 

 dark yellowish color. When broken in splinters, it gives off a 

 fine yellow powder, which has similar properties to litmus ; it turns 



