These lessons have been drawn up for students who are intending to follow cither the Course of Manual Training in Woodwork, as indicated in the instructions of the Science and Art Department, or that as specified by the City and Guilds of London Institute: to teach the use of tools employed in the handicrafts using wood, and to serve as a disciplinary educational course in training the hand and eye to accuracy, by a progressive series of exercises connected with Freehand and Drawing to Scale, and thus tend to produce thoughtful and efficient workmen.

Great care has been exercised in the choice of such dimensions of stuff as will avoid unnecessary waste, and yet not endanger the utility of the lessons, which arc graduated in the order of difficulty, being the result of considerable and successful experience in this branch of education. The success of the First Edition and the suggestions on Manual Instruction issued by the Department have resulted in a complete revision.

I hope this treatise may be found necessary, useful, and valuable in the training of all apprentices, youths, and artisans in the elements of the wood-working trades, the chapters on tools claiming special attention, as may be suggested by the results of the instruction given to Polytechnic students, who have during the past seven years been awarded eighteen gold, silver, and bronze medals by the examiners of the Worshipful Company of Carpenters, and the City and Guilds of London Institute.

The following observations must be regarded more in the light of suggestions than rules to be rigidly followed.

Before commencing to work with tools it will be found very useful to practice the younger children in cutting out and putting together solid models in card board or paper from plane projections (known technically as "nets"). All work with tools must, as stated in the Minute, be from careful full-size or large scale drawings prepared by the scholar. These drawings should, if not prepared in the workshop, at any rate be executed under the direction of the Manual Instructor, and they should, as far as possible, serve as working drawings for the practical exercises.

The tools required for the early stages of manual instruction in carpentry are the saw, the plane, and the chisel. The construction and mode of use of these tools, and demonstrations illustrating the proper methods of sharpening them and of keeping them in good working order should form the subjects for preliminary lessons.

Clear ideas respecting the various kinds of hard and soft woods, the growth and structure of wood, its fibre, and grain, and the uses of the different varieties of timber, may be given by means of a small collection of the chief descriptions of timber commonly employed in carpentry, with longitudinal and cross sections.

A great variety of exercises may be arranged, suited to the strength and ability of the scholar, in the use of these tools which will give an elementary knowledge of the principles of construction, and at the same time teach accuracy and carefulness.

The plan of instruction known as the Slojd System, though it possesses many excellent features does not in its earlier stages comply with the requirements of the Department, in that the exercises do not involve the use of the common tools employed in handicrafts, and work done at the school desk with a clasp-knife cannot be accepted as manual instruction in respect of which grants can be paid by the Department of Science and Art.

The earlier exercises should include some such as the following: - Sawing off across the grain of the wood, and sawing along the grain of the wood, blocks and strips of given dimensions taken from a drawing prepared by the boy himself, and having marked on it the required dimensions. Many varieties of tenon and of halved joints can be made in the rough by the saw alone.

The use of the plane can be commenced by planing small surfaces up to three inches in width and one foot or upwards in length, and then planing down strips to a given thickness. The planing of two surfaces at right angles to each other, the preparation of a right square prism and of a hexagonal prism, and the construction of a straight-edge with bevelled edges should follow later.

The joints used by carpenters form a valuable series of exercises in which the use of the saw and chisel may be learnt ; such as the various forms of halving, of mortise and tenon, notching, dowelling, dovetailing, groove-and-tongueing, and scarfing with keys or wedges. The teacher should draw up a complete series of simple and graduated exercises for the early stages which all members of the class should execute in turn. No attempts should be made at first to construct small articles of furniture. Neatness of workmanship and a due regard to finish should be insisted upon in all cases.

The proper use of nails and screws should be explained and practiced till a fair measure of accuracy has been attained. So far the instruction does not involve the use of curved surfaces. If the workshop is provided with a lathe, another graduated series of exercises might be arranged for more advanced students, to include the simpler forms of turning, but this is not insisted on.

There should be not less than four feet run of bench for each boy under instruction, and he should have a space of at least two feet in width in front of the bench. The room should be well lighted and ventilated. There should be a bench and set of tools for the use of each scholar when under instruction, with a proper place in which to keep them, each bench being provided with a wood or metal vice as the case may be. A teacher cannot properly direct the manual instruction of more than about twenty boys at one time.

221. A roof is intended to cover and protect a building from the effects of the weather, and also to bind and give strength and firmness to the fabric. To effect these purposes it should neither be too heavy nor too light, but of a just proportion in all its parts to the magnitude of the building. Mr. Ware observes, "that in practice roofs are generally made too heavy; and that he will do a most acceptable service to his profession who can show how a roof may be constructed with the smallest quantity of timber; by which an unnecessary load will be taken off the walls, and a large and useless expense saved to the owner."

The timber roofs of our ancestors, in the styles of building called Norman and Gothic, were generally made without horizontal ties at the feet of the rafters, and were intended be supported by the walls as an arch is supported by its abutments. The heavy walls they were in the habit of erecting in the Norman style, and the skilful disposition of buttresses the Gothic, rendering ties unnecessary ; besides, a tie beam would have been wholly incompatible with their mode of finishing the interior of a building.

Their principles of construction bear a closer analogy to masonry than to modern carpentry. It is true they sometimes erred in placing too great an oblique pressure against the walls, but in general we have more to admire than condemn in those celebrated buildings. The fashion of timber-framed roofs, as applied to great halls, originated about the reign of Edward III. They became common about the year 1400, and spans of considerable extent were roofed in a most judicious manner. The timber roof of the Gothic architects was generally executed in oak, and ornamented with bold and graceful mouldings, having richly carved ornaments at the joinings.

In the old Gothic buildings the roof is always of a high pitch; its outline forms a striking feature, and in general is in graceful proportion to the magnitude of the building: sometimes, however, it presents too extensive a plain surface, of which we have a notable instance in the roof of Westminster Hall. A high roof is in perfect unison with the aspiring and pyramidal character of Gothic architecture; but in the opposite, though not less beautiful style of the Greeks, it becomes a less conspicuous feature; indeed, many of the Grecian buildings were never intended to be roofed at all. Yet when a roof was necessary it was not attempted to be hidden, but constituted one of the most ornamental parts of the structure.

Of timber roofs we have no examples in Grecian buildings ; but the beautiful stone roof of the Octagon Tower of Andronicus Cyrrhestes, and that of the Choragic Monument of Lysicrates, are sufficient to show that they were more inclined to ornament than to hide this essential part of a building.

222. In carpentry, the term roof is applied to the framing of timber which supports the covering of a building. The pitch of a roof, or the angle which its inclined side forms with the horizon, is varied according to the climate and the nature of the covering. The inhabitants of cold countries make their roofs very, high, while those of warm countries, where it seldom rains or snows, make their roofs nearly flat; but the practice even in the same climate has varied considerably. Low roofs require large slates' and the utmost care in execution; they are cheaper, since they require timbers of less length and of smaller scantling. Formerly the roofs were made very high, perhaps with the notion that the snow would slide off easier; but where there are parapets a high roof is attended with bad effects, as the snow slips down and stops the gutters, and an overflow of water is the consequence; besides the water in heavy rains descends with such velocity that the pipes cannot convey it away soon enough to prevent the gutters overflowing. In high roofs the action of the wind is one of the most considerable forces they have to sustain, and it is supposed to have been with a view of lessening their height that the Mansard or curb roof was invented. The quantity of room lost by a curb roof, the difficulty of freeing the gutters from snow, and the ungraceful effect of the roof itself, are objections that are not compensate! by the small difference of the expense between it and a common roof, especially now that experience has proved that roofs may be made much less in height than our ancestors were in the habit of making them.

223. The height of roofs at the present time is very rarely more than one-third of the span, and should never be less than one-sixth. The usual pitch for slates is when the height equals one-fourth of the span, or when the angle with the horizon is 26<V degrees. Near the sea, or in very exposed situations, the height of the roof should be one-third of the span, for if less the rain and snow will be driven under the slates by the wind,