18th / 19th c. Dollond London slide rule w/ Inverted & Girt Lines for timber volumes

18th / 19th c. Dollond London slide rule w/ Inverted & Girt Lines for timber volumes

I have only found two sources of info about this item (Worthpoint – .worthpoint.com/worthopedia/dollond-london-england-slide-rule-1822641859 and Harvard University – waywiser.rc.fas.harvard.edu/view/objects/asitem/classification@Slide%20Rule/235/invno-asc?t:state:flow=c7923a80-24a1-481a-b5f7-ba9c2d9b20c2 ). Other than those sources I know nothing about slide rules.

Summary:-

Marked “DOLLOND LONDON” and “GIRT LINE” on one side, and “INVERTED LINE” on the opposite side. Overall length of the center sliding section is about 25″, and the body of the rule is about 24″ in length. It has tiny brass pins to note important marks on the rule.

Allegedly, Girt Line slide rules are used to calculate the volume of round timber, and Inverted Line slide rules are used to calculate the volume of rectangular timber.

The Dollond family started in business in 1750 making optical instruments, which was their primary business, and they continued in business with a variety of owners until 1927 when they became Dollond & Aitchison.

Condition: I have left unclean to preserve age. Please see photos.

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Description

18th / 19th c. Dollond London slide rule w/ Inverted & Girt Lines for timber volumes

Believed to be extremely rare. I have only found two sources of info about this item (Worthpoint – .worthpoint.com/worthopedia/dollond-london-england-slide-rule-1822641859 and Harvard University – waywiser.rc.fas.harvard.edu/view/objects/asitem/classification@Slide%20Rule/235/invno-asc?t:state:flow=c7923a80-24a1-481a-b5f7-ba9c2d9b20c2 ). Other than those sources I know nothing about slide rules.

Summary:-

Marked “DOLLOND LONDON” and “GIRT LINE” on one side, and “INVERTED LINE” on the opposite side. Overall length of the center sliding section is about 25″, and the body of the rule is about 24″ in length. It has tiny brass pins to note important marks on the rule.

Allegedly, Girt Line slide rules are used to calculate the volume of round timber, and Inverted Line slide rules are used to calculate the volume of rectangular timber.

The Dollond family started in business in 1750 making optical instruments, which was their primary business, and they continued in business with a variety of owners until 1927 when they became Dollond & Aitchison.

Condition: I have left unclean to preserve age. Please see photos.

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