CONVERSION AND PRESERVATION OF TIMBER 319 



" Planks from one-half to two-thirds the above time, according to 

 thickness. 



" If kept longer than the periods named, the thin tine shakes which 

 first open upon the surface during the process of seasoning will open 

 deeper and wider, until they possibly render the logs unlit for conversion. 

 If, however, the logs be reduced to the scantlings required after partial 

 seasoning, and then further allowed to dry, they- will not be liable to 

 tear open so much, but by shrinking gradually will retain a more solid 

 form, and be less objectionable to the eye when placed in position." 



In the case of pieces of wood less massive and thinner than the logs 

 and large beams already considered, the important matter is that the 

 wood shall be adequately seasoned, and free from cracks and other defects. 

 There is evidence that wood first partially seasoned in bulk, and then 

 fully seasoned after being sawn, is much inferior to that which is felled, 

 brought straight to the saw-mill, sawn at once, and then seasoned. 

 It is far more economical to season boards and small pieces in the latter 

 manner by artificial seasoning. WTien very large pieces are required, 

 such, for instance, as have been used in the restoration of the roof of 

 Westminster Hall, it is necessary, in order to obtain them in any respect 

 seasoned ready for use, that they should either be sawn out of fresh- 

 felled logs and then placed under cover for as long a period as possible 

 before use, or, if this is impossible, that they should be placed in position 

 as they are. It is a mistake to suppose that any good results from the 

 effort to obtain such pieces from trees which have been felled some years 

 previously ; while for this class of work considerable time can, as a rule, 

 be allowed for its execution. 



After conversion, the planks and scanthngs should immediately be 

 carried to a shed the ground of which has previously been carefully 

 prepared, while the choice of situation is also of importance. WTiile a 

 free current of air must be allowed, the timber should not be subjected 

 to any excessive draught, nor should it be exposed to the rays of the sun, 

 and it is essential that all wet should be excluded. The ground should 

 be level and sufficiently hard to bear the weight of the proposed pile. 



