| Name and Model Number | Keuffel & Esser 4017 Sperry Calculator |
| Country of Origin | USA |
| Date of Manufacture | 1909 |
| Front Scales | L, C, N^2(2 circles) |
| Back Scales | C (3 circles) |
| Scale Length | 4.7" (front scale); 12.3" (back scale) |
| Type of Rule | Watch Type |
| Construction | Metal with glass windows |
| Area of Use | Generic |
| Comment | Metal case with glass front and back.
Large stem wheel turns moveable front and back metal scale disks. Small stem wheel turns moveable front and back cursors; fixed cursors on glass front and back. Patent date October 25, 1904, with two wheels on stem, and fob loop at 7 o'clock. Serial No. 419. |
| Rarity | RR-RRR |
| Donor | Collection of Dr. Paul J. Tarantolo Jr. |
| Match Number | 34 |
| 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. |