|Name and Model Number||Léon Lalanne|
|Country of Origin||France|
|Date of Manufacture||circa 1850|
|Front Scales||The slider is visible through two windows in the body of the slide rule. |
The upper window handles trigonometric functions.
The lower window displays A,B,B and D scales in the normal nomenclature, and includes specialized gauge marks.
|Back Scales||The slider is visible through a single window. Two pairs of C and D scales are provided. |
A wide range of gauge marks are also provided, in French, including parameters relating to molten metals
and conversion factors for measurements new and old.
|Scale Length||247 mm (approx. 9.75”)|
|Type of Rule||Slide Rule|
|Construction||Cardboard and paper|
|Area of Use||Other|
|Comment||Probably used for metallurgy.|
|Donor||Collection of Trevor Catlow|
|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.|