|Name and Model Number||Carrett’s rule|
|Country of Origin||U.K.|
|Date of Manufacture||~1865|
|Front Scales||Routledge variant|
|Back Scales||Tables of general engineering facts and figures|
|Type of Rule||Rule|
|Construction||Boxwood and brass|
|Area of Use||Technical|
|Comment||A 2-foot, 2-fold for Engineering calculations.
Carrett’s rule has own special collection of different
scales and tables, examples are rare, this particular
one made by \Rabone is unusual in having a boxwood slide.
It too is amongst the rarest of the 2-2 slide rules.
|Donor||Collection of an English gentleman|
|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.|