|Slide rules HOME page||COLLECTION||SPECIALISED RULES|
|Make||Dring and Fage|
1. This rule was probably made for Customs and Excise in Britain who, among other functions, levy the duty on alcoholic drinks. On the side it is stamped "Customs and Excise" and has reference numbers DF43 and F6. This was probably an official serial number.
2. This rule was designed to measure the content of a cask (barrel) whether full or partly full.
3. It was provided with a dip-stick which is 40" long from the brass plate to the end and which is marked in inches and 1/10 of an inch. The brass plate was fixed precisely and had to be placed against a metal plate on the cask to ensure accuracy.
4. On one side the scales are:
Upper Stock: Two cycles of logarithms from 10 to 1000, marked A
On the other side the scales are:
5. As can be seen from the side view the rule has two "pointers". These were used to measure the diameter of a cask. They are set so that when the rule is closed the minimum distance is 2 inches. This is to allow for the shape of the points which in turn was designed to be able to fit into the head of the cask.
6. The scales were used as follows.
To get the volume of the cask when full:
To get the ullage (contents when partly full).
On this rule this calculation can only be performed when the cask is lying down.
7. The picture below, showing use of some of the items shown here, was published in 1896.
8. For another rule which can perform calculations for casks both lying and standing see here.
9. For more information on how such rules were used see here.
|Detail - effective diameter scale
||Gauging in progress
|Manufacturing date||c 1940|