(:title 1893-1898: Tavernier-Gravet Slide Rule:)

Slide rule inscribed " TAVERNIER - GRAVET  RUE MAYET 19 PARIS" and on reverse side (with conversion tables) "MÉDAILLES D'OR 1878 ET 1889",  and with cursor bearing the inscription "Presented to A. Norris.  W H Allen Son & Co. 1898."

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Tavernier-Gravet refers to a line of scientific instrument makers beginning with Etienne Lenoir (1744-1832) "ingénieur du Roi" who was succeeded by his son Paul-Etienner, then by Gravet around 1827 and finally by Tavernier around 1867.[^"RÈGLES A CARACTÈRE HISTORIQUE 1825 - 1943: Essai de datation des règles à calculer, LENOIR  -  GRAVET-LENOIR  -  TAVERNIER-GRAVET", [[http://www.photocalcul.com/Calcul/Regles/Collection_Etienne_Sigismond/introduction.html]], viewed 3 November 2012.^]

This particular slide rule design dates back to about 1814 or so by Lenoir who was the first slide-rule maker to employ a slide rule dividing engine, circa 1820 or so.  Specialist collector Bob Otnes has in his possession an early, pre-dividing engine example of a Lenoir from 1820 or so that is very similar to this rule, in particular noting that it was initially a pre-cursor design.[^Robert Otnes, Private Communication, 9 Oct 2012^]

The reverse inscription refers to gold medals received at Paris Exhibitions. In particular, the gold medal won in 1878 was awarded from the  //Exposition Universelle of 1878//, or "third Paris World's Fair" which was held between 1 May through 10 November 1878 celebrating, in part, the recovery of France after the 1870 Franco-Prussian War.  A very large exhibition of the latest developments in fine arts and technological achievement was on display (including Alexander Graham Bell's telephone). [^Described in "Exposition Universelle (1878)", [[http://en.wikipedia.org/wiki/Exposition_Universelle_(1878)]] viewed 3 November 2012.^]  As Fictor Nogo rhapsodised in his account of the opening of the exhibition "What is grand is magnificent. What is magnificent is sublime. The Exposition is sublime therefore it is magnificent and grand. A glorious Trinity of adjectives. In a word—France!".[^Fictor Nogo, //The Queenslander//, Brisbane, Qld, Saturday 3 August 1878. [[http://trove.nla.gov.au/ndp/del/article/19775347]], viewed 3 November 2012.^]]

The cursor of this slide rule is inscribed "Presented to A. Norris.  W H Allen Son & Co. 1898.".  W. H. Allen & Co. of Queen's Engineering Works, Bedford, was established in 1880 by William Henry Allen at the York Street Works, Lambeth, London.[^"W.H. Allen, Sons and Co.", //Graces Guide to British Industrial History//, [[http://www.gracesguide.co.uk/W._H._Allen,_Sons_and_Co]], viewed 8 October 2012^] In 1894  the business was moved from there to Lambeth in an area west of the Midland Railway main line designated for industrial development. It became a major engineering works and, eleven years after this slide rule was presented to Mr Norris,  in 1909 Allens received orders from the White Star Line for eight steam generating sets for the Olympic and the ill-fated Titanic[^W H Allen Engineering Association, "The Company: Early days in Bedford 1893-1914", [[http://www.whallenengasn.org.uk/whaeaweb2011_005.htm]],  8 October 2012^] (which three years later, on 15 April 1912, sunk with great loss of life).  Whether A. Norris was an employee of the company or an important client is not yet known.

The cursor is missing a glass window, and that is to be replaced with a piece of glass of the same dimensions  (0.052 in x 0.908 x 0.943 with etched hair line[^Robert Otnes, Private Communication, 9 Oct 2012^]) as the original on another rule of the same model.

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