Page 325 - Green - Maritime Archaeology: A Technical Handbook. 2nd ed

304 Maritime Archaeology: A Technical Handbook, Second Edition set square, and compass together with a drawing board can be used in field
situations or where one is working on a low budget.
C. PROFILING DEVICES
A number of interesting and ingenious profiling devices have been invented to transfer the profile of an object, say a small pot, onto drawing paper. One approach is to use an Aerial Sketchmaster (normally used for tracing aerial photographs onto maps) (Figure 11.6). Another, simple approach is to actively trace the profile of the pot onto the paper (Stevens, 1982). In this case, a set square is mounted on a base so that one edge stands upright and vertical from the plane of the drawing (Figure 11.7a). The pot is carefully mounted on a ring of Blue Tac, plasticine, or plastic silicon rubber so that it stands by itself, level and horizontal. The set square has a fine pencil lead inserted at exactly the junction between the edge of the set square and the drawing board surface. By tracing round the pot with the edge of the set square always touching the surface of the object, a pencil outline of the pot can be drawn. A lot of care is needed to set the pot up
Figure 11.6 Tracing device known as an Aerial Sketchmaster. Used mainly for photogram- metry, it can also be adapted to draw small artifacts. The instrument is set so the operator looks through a prism and can sketch the image on the paper below. The scale is usually set at 1 : 1.