An object lesson on the growth of an oak-tree could be given with the aid of large charcoal diagrams made preferably from the actual tree, leaves, etc., or from the drawings in Figs. 1 and 2 of this chapter. It will be readily seen that any number of familiar trees could be dealt with in this way, the oak, ash, plane, apple, and walnut-trees readily lending themselves to effective demonstration. For the purpose of object lessons, too much scientific data is not advisable, the chief aim is to arouse interest in botanical growths by indicating the main features of timber growth. The following data are suggested for a specimen object lesson, lasting some twenty or thirty minutes, the illustrations being prepared, as previously suggested, with charcoal on large sheets of white paper. To preserve these drawings for future use, they should be sprayed with a fixative and mounted upon millboards.

On Fig. 1 are shown various drawings illustrating some of the main characteristics of growth in oak-trees. An acorn is shown just after bursting with the small shoot coming towards the light, this of course occurring in the spring of the year. The next diagram shows the second stage with the shoot turned downwards in search of moisture and nourishment. In the third diagram the leaf shoot is illustrated, and coincident with this, the root has increased in size and also in the number of small or secondary roots, which act as feeders to the main root. The fourth stage, drawn from an actual specimen, shows main roots, secondary and hair roots, each one of the latter feeding the secondary roots and by means of them the parent root. As the tree increases in age and size, the roots spread over a much larger surface in order to satisfy the increasing demands of the small tree. The woody substance is formed by the ascending juices in the spring growth, some of these being deposited upon the stem. The rising sap, or natural juices, finally reaches the branches and twigs, causing the buds to appear and finally burst into leaf, and in some cases flower. During the summer season the roots are constantly extending themselves in search of natural salts and elements, which are in turn conveyed through the various parts of the tree to the flowers and later to the fruit. The oak, it should be noted, has no bright definite flower-unlike most other-seed-bearing trees. During the autumn after the fruit or seeds are mature a return of the sap and natural juices in a different form takes place; those have changed in some degree by atmospheric conditions and return in a less liquid form, forming a thick autumn layer of wood in their downward course. This can be clearly seen in most woods, darker in colour than the spring layer of the annual ring. Characteristic of the oak is"its system of extension,otherwise known as "ramification". New growths appear at right angles to existing twigs, hence the oak branches, practically at right angles to the parent growth, as shown in various diagrams in Fig. 2. The oak is peculiarly liable to foreign growths, such as "cluster galls,"shown in Fig. 2, oak apples, and currant galls, these being illustrated in Fig. 2. Suggestions for object lessons on trees, etc.:-1. General characteristics of timber trees:-

Fig. 2.-Characteristic detail of growth of the oak-tree.

Soft woods and hard woods. Introducing needle-pointed and broad leaves.

2. The growth of a tree from a seed:-

(a) Pine.

(b) Oak (see also Figs. 1 and 2).

3. Identification of trees from their barks.

(a) in summer.

7. Commercial value and uses of some English trees:-

(a) The oak.

(b) The beech.

(c) The apple.

(d) The cherry.

8. The seasoning of timber:-

(a) Water seasoning.

(b) Natural seasoning.

(c) Second seasoning.

(d) Desiccation or kiln drying.

9. The conversion of timber:-

(a) Felling.

(b) Lumbering.

(c) Shipment of timber.

(d) Cutting mill, machine and hand.

10. By-products of timber:-

(a) Charcoal.

(b) Tanning bark.

(c) Natural oils-turpentine, resins, etc.:-(d) Paper pulp from timber, (e) Gum, rubber, etc., extraction of. 11. The formation of wood illustrated by the growth of:-

(a) The plant.

(b) The sapling.

(c) The tree.

12. Geographical distribution of timber: -

(a) Australia.

(b) Russia.

(c) United States.

(d) England.

Shown by graph or chart illustrating ratio.

13. Trees as decorative media:-

Box, holly, etc.

14. Afforestation and re-afforestation. Need for, and statistics of colonies and foreign countries.

15. Effect of climatic conditions upon the growth of timber. Timbers peculiar to certain zones.

16. Leaves and their function. The pine needle leaf. Deciduous timber. Tropical growths.

Mother of Pearl, Japanese, and Blue Pearl are materials obtained from the shell of the pearl oyster, the former kind being so named because of its relation to the"pearl"which forms inside the shell and is almost detached from it. Pearl shell is composed of numerous layers of a crystalline carbonate of lime with but little animal matter. It is exceedingly hard and of a peculiarly lustrous colour. The best kinds of pearl oysters are found in the Indian Ocean, Red Sea, Gulf of California, etc., and Ceylon, where pearl fishing has been carried on for centuries. According to authorities on this subject, the pearl is produced by a small piece of grit or irritant entering the shell, which in time becomes covered with a secretion, forming a beautifully coloured stone-like gem of an oval shape. It was not until recent years that pearl shells were dealt in to any extent commercially; they were usually discarded after being opened, and the shores of some parts were strewn with these many feet deep. Now, however, they are an important branch of pearl fishing owing to the demand for pearl buttons, fancy articles, and inlaying material. For commercial purposes thick, good-coloured shells are much sought after. Important pearl fisheries lie to the North of Australia, the shells in that part being particularly suitable for commercial needs.

Ivory, the product of elephant tusks, is a beautiful material of peculiar milky colour used extensively for decorative purposes and especially for knife handles. An inferior substitute is walrus tusk, much used in place of the better and more costly material. Ivory in decorative woodwork is used chiefly in veneers, these being sawn by machinery. It can be rendered plastic by immersion in diluted acids which makes it transparent. The original colour can, however, be restored by a similar process. Old Italian craftwork shows fine examples of ivory inlay; it is most successful when used in small pieces with some woods as mosaic patterns. It can be fairly easily worked by means of saws, files, and glasspaper.

Tortoise-shell is a beautifully marked and coloured material from the shell of the tortoise. It is extensively used in fancy and ornamental turnery and cabinet work. Boule work of the Louis XV period is especially notable for the ornamental use of tortoise-shell. Added decorative effect is produced by painting the underside a vermilion colour, this showing through the lighter parts. The underside may also be gilded, by which means added brilliance of effect is obtained. Tortoise-shell can be advantageously employed in large masses, which is not the case with ivory and pearl. It should not be joined with square butt joints when connecting thin pieces, but spliced together, which effects a neater junction.