conics drawing machine
Date: 1955
Inventory Number: 1997-1-1619
Classification: Mathematical Model
Dimensions:5.2 × 29.6 × 21.2 cm (2 1/16 × 11 5/8 × 8 3/8 in.)
Accessories: mahogany box with plexiglass lid; pencil; eraser; box of lead; putty ball; cleaning cloth; cardboard instruction card
DescriptionThe conics drawing machine is stored in a mahogany box with a clear plexiglass lid that lifts off by a thumb groove and handle at one end. There are two main components of the machine, one of which fits on top of the clear plexiglass lid, and the other fits inside the box.
The piece that fits on top is the main panel of the apparatus. It consists of a rectangular white plexiglass panel. Two grooves are cut into the panel. The thickest groove is cut from the leftmost edge of the panel, almost to its center. This groove runs underneath a typed white instruction card fixed in the top left-hand corner of the panel. Above the leftmost end of this groove, a rounded blue plexiglass post is fixed to the panel, possible a handle for holding the panel steady or lifting it off of the box.
The thinner grove begins in the bottom left-hand corner of the panel and cuts diagonally towards the center. Two blue axes are marked on this groove: one is very short and vertical, cutting across the groove nearly at the bottom left-hand corner of the panel. The other is slightly longer than the horizontal component of the groove. It begins at the same place as the vertical one, and runs parallel to the bottom edge of the panel almost to the center. These two axes cross at their mutual intersection point with the groove. This point is labeled "O'". A small blue plexiglass cylinder with a white plexiglass top marked "C'" slides back and forth in this groove.
There are two more blue axes marked on the surface of the panel. These two divide the panel into four equal quadrants, and meet in the center. The horizontal axis turns into the first thicker groove on the left hand side. In the center, where the axes intersect, is a small hole framed by a brown plexiglass cylinder. Right at the intersection, above the horizontal axis and right of the vertical axis is written "F". Below the horizontal axis and right of the vertical axis is written "O". Various ellipses and parabolas are marked on the panel in blue, beginning at the origins. They are possible templates for users. In between the two horizontal axes (the one in the center of the panel and the one at the bottom, accompanying the diagonal groove) is a short horizontal black like that begins at the vertical axis in the center and extends slightly to the left. This line is labeled "a". One small black arrow on this line points to the right, towards the vertical axis. Four small black arrows on this line point to the left, towards the leftmost edge of the panel.
The second main component of the apparatus is an asymmetrical heart-shaped piece of clear plexiglass. It is constituted of two arms that form a right angle, and two arc sections: one smaller section on the left and one larger on the right, that intersect off center. A blue line of raised plexiglass runs the length of the smaller arc section. Above it, a scale is written in black. Thirteen small black lines divide the arc section into fourteen parts. The increments are smaller at the ends of the section and larger in the center. The second line from the left is labeled 0.5. The seventh line from the left is labeled 1.0. The second line from the right is labeled 1.5. Above the scale in the center is written "e" with a black arrow pointing to the left and to the right on either side.
An additional clear plexiglass arm is attached to this apparatus. It is attached partway down the leftmost main arm such that it is a radial arm for the leftmost arc section. It is attached to the main arm by a pivot so that it can be set to point at any place on the scale. The base of the arm is labeled "B". The tip of the arm that is next to the scale has a blue knob attached to the left that can rotate. Users must set the arm and the knob to the desired increment on the scale before use.
The apparatus is designed to be used with threads pulled taught through its various orifices. A piece of thread is still visible in the diagonal groove cut from the main panel. The spool of thread referenced in the instructions is missing from the apparatus. It may have looked something like the spool of thread from 1997-1-1639.
A white cloth, possibly for cleaning away eraser debris, is stored inside the mahogany box. In addition, a half-circle clear plastic dish containing an erasure, a box of lead, a white mother-of-pearl colored pencil, and a block of putty, is also stored in the box.