Local conditions affect lumber very much. While the great lumber interests formulate and publish schedules of grades, the user cannot, from their designations and descriptions of grades alone, make an economical selection. The designations "first " or "best quality," "without imperfections," etc., inserted in specifications to describe the quality desired, tend to get all concerned into trouble on account of the various meanings put on these terms.

Some markets are well supplied with good spruce framing lumber, while an adjoining section will have no spruce, but good, rough pine or hemlock. The same differences will be found relative to finishing lumber. The student should visit each lumber yard; look over the stocks; find the materials in that market, how they are graded, so that he can in specifications state just what imperfections can be allowed in framing timber, boards, or finishing lumber, always bearing in mind that there is no material in existence which is free from imperfections. By observing the imperfections and stating clearly what will be allowed and what will not, he can avoid very many unpleasant misunderstandings, with the owner especially, and also with the builder.

Lumber which has the largest number of good qualities is the most expensive; therefore, for each portion of the work, material should be required having only the particular qualities required for the station.

Since, in the case of lumber, the questions of grade, quality, etc., can be determined by observation rather than by such experiments as are indicated for cement or sand, these matters will not be further treated here; but in the following specifications, there will be illustrated what consideration should be given generally to lumber grades, quality, and finishes.