5. The constituent parts of buildings having been explained in the article on architecture, it is unnecessary to enter here into minute details on this point; nor would a particular description of the various operations of the carpenter and joiner be useful to the general reader, since, in every place, means are at hand by which a general view of this business may be obtained by actual inspection. 6. The carpenter and joiner are guided, in the performance of their work, by well-defined rules, drawn chiefly from the science of Geometry, and which they have learned from imitation and practice, as well as, in many cases, from the valuable works which have been published on these branches of the art of building. 7. The principal tools with which they operate are the axe, the adze, the saw, the auger, the gauge, the square, the compasses, the hammer, the mallet, the crow, the rule, the level, the maul, and the plane; and of many of these there are several kinds. 8. The timbers most employed in building in the United States are chiefly pine, oak, beech, black walnut, cypress, larch, white cedar, and hemlock; but of these pine is in the greatest use. Oak and beech are much used in constructing frames, in which great strength is required. Of the pine, there are several species, of which the white and yellow are the most valuable; the former of these grows in the greatest abundance in the Northern, and the latter, in the Southern states. 9. Vast quantities of timber are annually cut into boards in saw-mills, and floated down the rivers from the interior, during the time of high water in the spring and fall, and sometimes at other seasons of the year. The boards, or, as they are frequently denominated, planks, are placed in the water, one tier above another, and fastened together with wooden pins. Several of such _rafts_ are connected by means of withes to form one; and, at each end of this, are placed one or two huge oars, with which it may be guided down the stream. Upon these rafts, shingles and laths are also brought to market. 10. Logs and scantling to be employed in the frames of buildings are also conveyed down the rivers in the same manner. The business connected with the production of shingles, laths, boards or planks, and staves, is called lumbering; and it is carried on, more or less extensively, in the regions near the sources of all the large rivers in the United States, and in the British possessions in North America. 11. The trade in lumber has also given rise to another class of men, called lumber merchants; these purchase the lumber from the original proprietors, who bring it down the rivers, and, in their turn, sell it to builders and others. The lumbering business employs a large capital, and a numerous class of our citizens. [Illustration: STONE-MASON.] THE STONE-MASON, THE BRICKMAKER, &c. THE MASON.