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Use Modern Adhesives:
Some restorers will use modern adhesives that are reversible to enable their work to be undone at a later stage. While their intention is admirable, since most adhesives used in restoration are animal based and thus reversible anyway, this should be unnecessary. Of course, if the work is correctly undertaken and suitable materials and woods are used, there should be no need to undo the work.The development of moisture- and heat-resist¬ant adhesives has greatly advanced the demand for plywood, and for its counterpart, laminated wood. In the latter, the layers of wood, either veneers or boards, are laid together with the grain of all the layers running in the same direction, thereby providing a product of great longitudinal strength. Plywood and laminated wood are widely used in boats. Improved adhesives have also contributed to the use of laminated members for heavy truss construction, to the gluing together of narrow boards to make wider ones, and to the making of finger joints by which short lengths are joined to make longer pieces. This has materially assisted in expanding the use of otherwise waste materials.
See Also Features Modern Cycads:
This is revealed by the fact : they combined fernlike foliage with seed pro-tion. Then, too, the primary vascular struc-: was fernlike, but the presence of secondary )d was a feature more characteristic of seed its. The pteridosperms were probably derived n ferns during Upper Devonian time. Then ing the latter part of the Paleozoic era some :hem became more specialized and gave rise he cycads. Such features modern cycads in modern cycads as large pith with gum canals, the thick cortex, pinnately compound foliage, the 'presence of :ripetal xylem in the cone axis, and the highly jnchymatous secondary xylem all point to •idospermous ancestry. A peculiar feature of all Paleozoic seeds is the absence of visible embryos. Many well-pre¬served seeds have been sectioned and studied, but nothing that can be unquestionably regarded as an embryo has ever been found. It appears that the dormant embryo, such as exists in mod¬ern seeds, was a post-Paleozoic development in plant evolution, and that the oldest seeds were little more than mere ovules which entered into the dormant state before visible embryos were formed. Some modern plant morphologists object to considering the pteridosperms as seed plants because of the embryoless condition of their so-called seeds. They claim that pteridosperms shed ripe ovules but not seeds, and they were therefore intermediate between spore-bearing plants like the ferns and the true seed plants.The gymnosperms evolved during the Paleo¬zoic era, probably about 400 million years ago, and are thus much more ancient than the an¬giosperms, which appeared about 135 million years ago and probably were derived from a gymnosperm ancestor. It is believed that the earliest gymnosperms were the seed ferns and the Cordaitales. The conifers appeared about 300 million years ago, and were followed by the ginkgos, cycads, and others. Of all the gymno¬sperm groups, the only ones that are still in ex¬istence are the conifers, cycads, ginkgos, and Gnetales. The cycads, ginkgos, and Gnetales are just about holding their own in competition with the more successful flowering plants. The pre¬dominant gymnosperms are the conifers, which make up more than 30% of the forested areas of the world.
On The Other Hand See Present Antique Frames:
Picture Framing The framing of pictures is a matter of great importance. Etchings, water colors, oil paintings, Japanese prints, pencil drawings, and photo¬graphs all require varying types of frames. Some are better under glass, some without; some require ornate frames, others the simplest ones pos¬sible. The frames of a generation ago were almost invariably bad. They were too heavy and elaborate, often overloaded by shadow boxes, and in many cases were more important than the pictures they contained. Fur¬thermore, these frames were of plaster and not of carved and gilded wood, as were the beautiful frames of the 18th century. Designs were poor and of a commercial character. At present antique frames are much in de¬mand for both genuinely old paintings and prints.As a rule, oil paintings should be framed without mats or glass, al¬though today narrow borders, either painted or covered with natural-colored linen, are in vogue. Logically, modern oil paintings require simpler frames than do the old masters, although antique frames are often used on ultramodern pictures.
