Abstract: An optical fiber preform includes a core rod and an overclad tube having an open, distal end dimensioned to enter the mouth of a vertical fiber draw furnace. A plug is fixed in the region of the distal end of the tube, and the core rod is disposed axially inside the overclad tube so that a distal end of the rod is restrained from downward movement by the plug as the tube enters and descends into a hot zone of the draw furnace. The distal end of the tube is heated in the furnace hot zone until the tube and the plug soften and fuse with one another. The tube then collapses onto the core rod to produce a drop from which an optical fiber having desired properties may be drawn.

Abstract: An improved book holder having a backrest portion which connects a base plate for supporting the lower edge of an open book and a top plate which is adjustable to close toward and contact with the upper edge of the open book wherein the improvement comprises a plurality of extender means attached to either the base plate or the top plate and inclined such as to accept the hardbound cover of the open book at or near the backrest and to close inwardly upon the pages such as to make contact with the pages; such contact being made with friction pad members secured to the extender means for preventing the accidental page turning of the book. The use of such extenders in combination with the book holder allows the book holder to easily hold hardbound books, loose leaf pages in hard cover binders and the like.

Abstract: A book holder having a backrest portion which connects a base plate for supporting the lower edge of an open book and a top plate which is adjustable to contact the upper edge of the open book, and inwardly facing frictional pad members secured to the base and top plate for preventing the accidental page turning of the book.