| Name and Model Number | Appoullot T2 and T3 LogZ Spiral Slide Rules |
| Country of Origin | France |
| Date of Manufacture | c. 1930s |
| Front Scales | C, L, 3 revolution number scale, special root scales, tangent & sine scales. Scales wrap in a curious artistic way. Outer scales have accessory vernier scales for increased precision. |
| Back Scales | none |
| Scale Length | 3 revolution spiral number scale is about 60 cm long on the T2 model (13 cm diameter disc) and 79 cm long on the T3 model (20 cm diameter disc). |
| Type of Rule | Disc |
| Construction | 13 cm diameter (Model T2) & 20 cm diameter (Model T3) irregularly shaped enameled aluminum discs, with two transparent celluloid cursors. Fitted leather cases. |
| Area of Use | Generic |
| Comment | Also produced in as a larger Model T4 with a 140 cm long spiral on a 30 cm diameter disk. Curious artistic arrangements of scales with a spiral scale jumping another scale. Cursors also have curious shapes. I have instructions (176 pages) by L. Appoullot copyrighted 1931, entitled: La methode du LOGZ par L'Inventeur du LOGZ. (The method of LOGZ by The Inventor of LOGZ.) I also have sales literature promoting the LOGZs as "Ateliers de Précision" (Workshops of accuracy)
|
| Rarity | RRR |
| Donor | Collection of Ed Chamberlain |
| Match Number | 153 |
| 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. |