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Sydney Prentice  

Every scientific illustrator must devise a way to transform specimens from three-dimensional objects into images on a two-dimensional surface (i.e. paper, canvas, etc). Sydney Prentice, seen in the photo on the left, adapted an apparatus called a pantograph, which was usually used to resize maps, drawings, etc. (before the days of reducing copy machines), to perform this task.

Prentice attached a long, metal rod to the pantograph's stylus and traced the outlines and major landmarks of the bones. This gave him a perfect isometric drawing of the specimen. He could also set the pantograph to copy the specimen at whatever size he wished (1/3 actual size, 1/2 actual size, etc.), which was especially helpful when drawing large fossils, such as whales. In that way, he obtained an accurate, though very rough, preliminary sketch from which to begin his drawing.

pantograph drawing pantograph

Sample pantograph drawing on left; pantograph in its box on right.

Mary using pantograph

Mary Parrish is using Prentice's pantograph to draw a fossil whale skull (left). 1 - shows the pencil on the paper on the table recording here movements on the whale skull at 1/3 the acutal size of the whale skull. 2 - shows the stylus tracing the whale skull.

We are convinced that the pantograph housed in the Department of Paleobiology is the actual one that Sydney Prentice used to prepare his preliminary sketches. While interning, Julia Coursey (with the help of Dave Bohaska, museum specialist, Department of Paleobiology) assembled the pantograph for what is likely the first time since Prentice used it, and tried his technique. Instructions for setting up and using the pantograph could not be found, so Julia experimented in order to determine how to set up and use the apparatus. She then wrote the set of instructions (below) to help others use the pantograph in the future.

pantograph with labels

Parts of pantograph:

1) a heavy black metal stand to anchor the pantograph (two wires attach to the highest point, and two holes in the base to support the arms of the pantograph; 2) a very heavy horseshoe shaped weight to secure apparatus 1); 3) a large “butterfly” screw to attach 1) to 2) (for screwing the stand onto a table for stabilization if desired); 4) four metal bars (which form a parallelogram) with attachments for a writing implement and stylus; 5) a metal mechanical pencil holder and two boxes of graphite leads; 6) four circular weights with holes in the middle; 7) two short metal styluses; 8) four long pointed metal styluses; 9) two metal wires with hooks on each end; and 10) tacks (probably used to secure his drawing paper); and 11) a few unidentifiable odds and ends.  All but the heavy metal objects are contained in a beautiful wooden box.

Assembling the pantograph

a) Find a large level work area, with plenty of room for both your specimen (or drawing to be traced) and the pantograph. Position the heavy black metal stand (1) in the top left corner of the space, arm facing the bottom right corner. Place horseshoe shaped weight (2) on the arm to secure it in place. If working on an appropriate surface, feel free to screw the arm to the table with the butterfly screw (3).

b) Assemble a parallelogram from the metal bars (4). Three of them should remain attached to each other in the box, leaving only one to bar to be added. Unfold the three bars until they form a U shape, and then place the sliding pieces on either side approximately level with one another. Unscrew the knobs on either side so that the remaining bar (cross bar above) may be attached. It should lie on top of the U shape, not underneath, to allow the pantograph to move.

c) Determine which corner of the parallelogram is the anchor point – the corner furthest from the stylus attachment – and attach it to the metal arm by placing the protrusion on its lower side (seen in upper left corner of (4) into the lower hole of the heavy black metal stand.

d) Attach one wire (9) to each of the sides of the parallelogram closest to the metal arm. There are loops on the top of the metal arm and the corners of the parallelogram, upon which you should hook the ends of the wire. The loops on the corners of the parallelogram may require you to unscrew the sliding piece to which the loop is fastened before hooking the wires to them.

e) Load a graphite lead into the mechanical pencil (5), and insert the mechanical pencil into the holder (inserting the lead through the lower side of the parallelogram).

f) Choose the stylus most appropriate to your drawing (or specimen)(7, 8), and place it in its holder.

g) Slide the bottom side to the appropriate scale, located on (4), for your reduction. The vertical sides of the parallelograms have measurements on them, so be sure to have a consistent position for each side.

h) Tape (or tack) (10) down some tracing paper under the pencil, positioned such that the entire sketch will fit. Tape (or tack) down your image (if tracing an image) or secure your specimen (if tracing a specimen).

i) Slide 1-2 weights (6) on the end of your pencil, so that the pressure on the pencil will be even, and to ensure that the pencil lead touches the paper even as the lead itself is wearing down.

j) Use the stylus to trace your specimen by lifting the end of the stylus up and down and controlling the horizontal movement with the wooden handle.

Julia using pantograph

Julia Coursey is using the pantograph to trace a drawing. Note the position of the pantograph.