| Name and Model Number | Aristo 958 GEODAT |
| Country of Origin | Germany |
| Date of Manufacture | 1950-1970 |
| Front Scales | ctg, tg, arc, pix, pix, 1/pix, 1/x, x, x, sq rt i-xsq, sin, cos |
| Back Scales | 1-cos, 1-cos, x sq, x sq, 1/tg alpha.2,sin cos, cos sqx, x, lgx, x cubed |
| Scale Length | 25 cm (10 inches) |
| Type of Rule | Slide Rule |
| Construction | White plastic |
| Area of Use | Topography |
| Comment | Duplex civil engineers or surveyors slide rule with stadia scales. |
| Rarity | RR |
| Donor | Collection of Clay Castleberry |
| Match Number | 316 |
| Thumbnail (Click Picture for Details) |  |
| In conjunction with our 'donors' we assign a rarity rating to each item, based on the system devised by Herman van Herwijnen |
| (1929 - 2004), renowned Dutch collector, author, and creator of Herman's Archive, a collection of 5,000 slide rule images on CD. |
| • RR = Rare - 1 of 25 collectors has one; it may take a year to find an example in the marketplace. |
| • RRR = Very Rare - only a few known to collectors; may be several years before it comes up for sale. |
| • RRRR = Extremely Rare - a museum piece; unlikely that an example will come up for sale. |