|Name and Model Number||Edward Roberts six-slide Everard|
|Country of Origin||England|
|Date of Manufacture||~1765|
|Front Scales||See comment section|
|Back Scales||See comment section|
|Type of Rule||Everard|
|Area of Use||Gauging|
|Comment||Four of the scale sets are traditional to four-sided Everard rules.
The traditionally narrow faces of a four-slide are the wide faces in this example
because of the addition second slides to both of these faces.
Both additional slides have single decade 1 - 10 logarithmic scales on both edges.
The upper edge of the rule body is also a single decade logarithmic scale.
Possibly a special order Everard with the added scales designed to facilitate
basic multiplication and division.
|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.|