Full Details

Name and Model Number Tyler by Weems and Plath
Country of Origin U.S.A.
Date of Manufacture  
Front Scales L,C,A,S,T,S2,T2,ln
Back Scales None
Scale Length 19 cm diameter
Type of Rule Slide Rule
Construction Plastic
Area of Use Generic
Comment An interesting log spiral scale.
Rarity RR
Donor Collection of Rod Lovett
Match Number 29

RR = Rare -- 1 of 25 collectors has one; it may take a year to find an example in the marketplace.   
RRR = Very rare -- only very few known to collectors; may take several years before one comes up for sale.   
RRRR = Extremely rare -- a museum piece; unlikely that an example will ever come up for sale.