French

Marc, Paris five inch slide rule, also branded UNIS. It appears to be made of celluloid, with a celluloid and very thin nickel plated, brass cursor. It has a leather slip case and has International Combustion Limited printed on the back and a cm scale. Scales are: inches\A{B,C}D//cm. UNIS stood for Union Nationale Inter-Syndicale, an organisation for the promotion and protection of French products, founded in 1916.

Graphoplex 640 ten inch, closed frame, plastic slide rule. It has the following scales: cm\L,P,A{B,K,C1,C}D,LL3,LL2,LL1//{ST,S,T,C}. It has a burgundy plastic case, card of tables, etc, and an instruction leaflet.

Graphoplex 620d Rietz ten inch, closed frame, plastic slide rule. It has the following scales: cm\K,A{B,C1,C}D,L//{S,ST,T}. It has a burgundy plastic case, card of tables, etc, and an instruction leaflet. The latter are the same as for the 640 rule above and the reverse of the card is shown this time.

This slide chart, made by IWA, no: 07116 for Ideal Standard is designed for selecting the appropriate size of “Fluxair” convector from their range where the difference between the mean temperature of the water in the convector and the ambient temperature, the heat to be emitted per hour, and the water flow rate are known. Other calculations can also be made relating to the pipework used.

Tavernier Gravet ten inch, closed frame, plastic slide rule. Scales are the usual Rietz ones: cm\K,A{B,C1,C}D,L//{S,ST,T}. It has a card case.

Graphoplex 612 (Rietz) five inch closed frame, plastic slide rule, complete with leather slip case. Scales are: cm\K,A{B,C1,C}D,L//{S,ST,T}. However they are labelled differently on the front face, as B³,B²{b²,a,b}B,L.

Calculigraphe calculator made by Henri Chatelaine in Paris. Rotating the winder alone rotates the back scales. Rotating the winder with the button depressed rotates the two hands (cursors) together. There is a fixed cursor on the rear glass.

France has a long history of slide rule making and one of the best known ‘standard’ designs was invented by a French artillery officer, Amédée Mannheim in about 1850. Tavernier Gravet, in their previous guise as Gravet-Lenoir, were early makers of these Mannheim rules.

Another Marc 5” slide rule, this one was a promotional for Buhrings Filters Limited and Hoveman Brothers London. Both names are printed on the back of the rule and the latter is also printed on the leather slip case. Both cursor and rule are celluloid. Scales are A{B,C}D.