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LIGHTING
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The Preservation Book Cradle
Holds and Protects Delicate Book Structures During Digital or Photographic Copying Designed by Alan Buchanan U.K. Patent Application No. 960344901 GB 2310165A
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THE PRESERVATION BOOK CRADLE holds safe books of a delicate construction whilst the pages are turned during the process of digitisation or photography. The book rests in the best position with the spine properly supported. One platform is moved relative to the other with infinitely small adjustments so that stresses in the book's spine are reduced to a minimum. The lights are cool, with the correct colour temperature, so there is no heat gain at the surface of an object page thus avoiding shrinkage during the process. |
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The Preservation Book Cradle has one fixed platform and one which is moveable. In figures 1,2 & 3 the fixed platform is on the right and the moveable one is on the left. The platforms are linked by a channel which can contain resilient material to support the book's spine. The cradle is adjusted to the thickness of the book's text-block. The book is laid on the moveable platform, the top cover is opened to lay against the fixed platform and the spine is supported by material in the channel (see figure 1). As the pages are turned the moveable platform, maintaining its orientation perpendicular to the axis of the camera lens, is moved upwards and the channel follows (see figure 2) until the whole text-block has been turned and is resting against the fixed platform (see figure 3). The rectos of each leaf are digitally recorded; the book is turned round and the versos are then recorded. The computer's software arranges the pages in sequence. |
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CONSTRUCTION The cradle is constructed in aluminium. The platforms that support the book are slotted to enable straps, etc., to be fastened, and are painted matt black against reflection. The fixed platform is adjustable to permit the angle through which the leaves of the book may be turned to vary between 70° and 110°. The cradle is designed to support books with text-blocks between 25mm and 125mm thick and boards up to 12mm thick. It can carry books up to 500mm high and 360mm wide. The centre point of the camera trolley has movement between 0.5M and 1.0M distance from the book's object page and is drilled for three positions of the camera. There are two positions for the frame supporting the camera trolley; the first so that the centreline of the camera lens is perpendicular to the book's object page; the second, perpendicular to the object page if this page were turned through a further 5°. This second position is to allow for the introduction of a vacuum wedge beneath the object page, to constrain it without obscuring its upper surface. |
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There is an independent light on each side of the cradle comprised of a base plate, a 16mm diameter column, an adapted Arri lighting grip and an aluminium cowl, black on the outside and white on the inside. The lighting uses 3 single-ended fluorescent Biax L lamps by G.E. Lighting in each cowl. The lamps have high frequency ballasts. and each lamp generates an output of 40W whilst consuming only 10W. Thus, each cowl has an output of 120W and a heat gain of 30W. The colour temperature is 3500°K; the U/V light generated is negligible. Each cowl is fitted with a balanced shutter so that the operator need not switch off after each exposure. There is a single 12 core cable from each cowl to a box containing the ballasts. The top of the box has a fused mains switch on it and other switches that permit 1,2, or 3 tubes to be lit in each cowl. OPERATION OF THE PRESERVATION BOOK CRADLE The moveable platform is suspended from 4 hangers each of which rotate between 2 axles, one at the top and one at the bottom. The distance between the centrelines of each axle should equal the thickness of the text block of the book to be recorded or, more precisely, the distance between the hinge points at the spine ends of the book's covers. Callipers are used to measure the distance and to transfer it to each axle. All hangers should be adjusted roughly together; were one hanger to be radically adjusted but leaving the other 3, the moveable platform could distort. The thickest boards of a book in those to be recorded in Oxford University's current programme are 20mm. Hence, there is 20mm from the centre of the lower axle to the surface of the moveable platform and so this particular book's lower board would rest with no padding on the movable platform. For any other book packing of 20mm less the thickness of that book's boards should be provided. For the fixed platform there is a maximum depth of 12mm and the same logic applies. However, the system is not particularly sensitive on this point and, though Oxford have changed the thickness beneath the book on the moveable platform they have left the packing to the fixed platform unchanged at 12mm thickness of Zotefoam's EV50. EV50 is a soft foam but with the greatest resilience of the range. The hangers adjusted to the thickness of the text block and suitable packing provided on each platform, with the moveable platform in its lowest position the book is placed upon it, closed, with the joints at the spine ends of the book's covers coinciding with the centres of the axles at the channel end of the moveable platform. The upper cover is opened and turned to rest against the fixed platform. This configuration is as, 'Book on Cradle' of Figure 1 of the diagram. The angle between the two platforms can be adjusted to suit the book's ability to open from 70° to 110°; Oxford have kept it at 100° throughout their present programme. Each page is turned to rest against the upright platform and as necessary, the handle is turned that causes the wormgear to push the moveable platform upwards and outwards; the binding evinces signs of stress if the pages yet to be turned start to bow more than usual. Oxford hold in place the pages that have been turned with strips of polythene 75mm wide by 750mm long. The strip has 75mm of sticky backed Velcro on each end and sticky backed Velcro is on the side of the struts on each side of the upright platform. The object page is gently held in place using the tips of bone folders. They keep to hand lead snakes, which hang over the upper edge of the moveable platform and lead filled cushions 50mm by 37mm. An opaque black cloth hangs beneath the object page; Oxford use crepe-de-chine but claim that black stone washed silk would be better.
Other pieces of equipment used are:
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