| Name and Model Number | K&E 4138 Morrison Radio Rule |
| Country of Origin | USA |
| Date of Manufacture | |
| Front Scales | L F A = B CI C = D T ST S |
| Back Scales | 9 8=7 6 5 4 = 3 2 1 |
| Scale Length | 10 ins |
| Type of Rule | Slide Rule |
| Construction | Mahogany celluoid, glass cursor |
| Area of Use | Electrical |
| Comment | Designed for radio electronics, the slide rule has 9 specific scales to solve a variety of problems.
Reverse Scales: 1 dB decibels 2 E field intensity 3 s soil conductivity 4 f frequency 5 P Power 6 Ed field intensity x distance 7 d distance 8 & 9: Attenuation factor |
| Rarity | RRRR |
| Donor | Collection of Wayne Harrison |
| Match Number | 405 |
| 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. |