ediograph
Date: circa 1860
Inventory Number: DW0518
Classification: Pantograph
Dimensions:large central crosspiece: 9.2 × 87 × 15.2 cm (3 5/8 × 34 1/4 × 6 in.)
case: 12.7 × 91.5 × 15.7 cm (5 × 36 × 6 3/16 in.)
Accessories: original mahogany storage case
trade card from William D. Hocker, Inc
two original curatorial cards
DescriptionThe ediograph consists of three square brass bars: one thick central bar and two thinner bars. Each thin bar runs through sleeve fixed to the bottom of a brass wheel attached to one extremity of the main bar. Each wheel has a screw pin at the top that can be loosened to permit the thin bar to slide back and forth through the sleeve. The thin bars have incremental markings engraved on their topmost surface. There is a rectangular hole on the top of each wheel through which those markings can be viewed. There is a further set of increments engraved on each wheel just underneath the rectangular hole permitting more precise placement of the thin bars relative to the main bar.
The main bar itself runs through a sleeve fixed above a brass disc. Unlike the end-wheels, the disc is below the bar, sitting on the surface below. The main bar has engraved incremental rulings along a side face, and these are visible through a rectangular hole in the sleeve through which the main bar slides. There is a further set of incremental engravings underneath this rectangular hole.
Each of the end-wheels on the main bar has a groove around the circumference. There is a long band that runs around both wheels, fixed in the grooves. The band is partitioned in two, with brass attachments at each of the ends permitting it to be closed into an elliptical shape around the wheels. The middle section of each half of the band (the sections that sit on the circumference of the end-wheels) is flat, black rubber. This section becomes thinner and round as it approaches the brass connecting ends. The main sections of the band run parallel to the main bar.
There is a brass stylus attached to one end of one of the side brass bars (call this bar A). There is a brass attachment at the opposite end of the other side bar (call this bar B) to which users can attach a writing instrument.
There is a thin white string that runs from a loop above the brass stylus, through a loop above the wheel attaching bar A to the main bar, along the main bar, through a loop above the wheel attaching bar B to the main bar, and ending at a loop above the brass writing utensil attachment.
The ediograph is stored in a long, rectangular, mahogany box. The lid is attached to the bottom part of the box by three hinges along a long edge of the rectangle. There is a metal key hole on the outside of the bottom half of the box. There are two metal hooks on the front of the bottom of the box that fit into loops on the outside of the lid to keep the box closed.
There are several wooden inserts lined with green felt used to hold the various parts of the instrument in place inside the box. The instrument has to be disassembled before storage. The two thinner brass bars can be slid completely apart from the main bar and they are fixed in holders attached to the inside of the lid of the box. The white string remains attached to the thin bars and so is stored in the lid of the box. The main brass bar sits in the bottom half of the box, with the main central brass disc in the center and the end-wheels at opposite ends of the box.