|Name and Model Number||Favor, Ruhl & Co. |
SR108 & MD7
|Country of Origin||USA|
|Date of Manufacture||c. 1945|
|Front Scales||K A [ B S T C ] D DI|
|Back Scales||[ L C2 C1 ] D1 D2 D|
|Scale Length||12.5 cm|
|Type of Rule||Slide Rule|
|Construction||Celluloid laminate over wood duplex slide rule 18-cm long; with plastic cursor.|
|Area of Use||Generic|
|Comment||Open frame extended scale duplex slide rule with C1, C2, D1 & D2 scales extended, giving an effective scale length of 25 cm on a 12.5 cm slide rule.
Made by Charvoz-Roos for Favor, Ruhl & Co. Model Nos. SR108 & MD7 both appear on slide rule.
Also made for Frederick Post Co. during WWII and labeled as Post's No. 1442.
|Donor||Collection of Ed Chamberlain|
(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.|