Unique are well known for their range of wood slide rules with celluloid covered paper scales, which, in spite of their cheapness, have survived in large numbers. The firm was founded by Burns Snodgrass in Brighton in 1920 and continued to manufacture slide rules until 1975. Burns Snodgrass (died 1954 aged 68) was also the author of “Teach Yourself the Slide Rule”

Three Unique slide rules: The upper one is a Unique “Log Log” ten inch slide rule. Its scales are: LU,A{B,C}D,LL. It has tables of trig functions and formulae on the reverse. Like most of the rules on this page it is made of wood with celluloid covered paper scales and is closed frame. It has a black card case.

The second rule is an “Electrical” ten inch slide rule. Its scales are: LU,FAHT,DF{CF,C1,C}D,CENT,LL. It has tables of resistivity & temperature coefficient on the reverse. It has a maroon card case.The CF & DF scales are folded at π.

The third rule is a “Universal I” ten inch slide rule. Its scales are:LU,S,A{B,C1,C}D,T,LL. It is missing its cursor. It has a black card case.

The second rule is an “Electrical” ten inch slide rule. Its scales are: LU,FAHT,DF{CF,C1,C}D,CENT,LL. It has tables of resistivity & temperature coefficient on the reverse. It has a maroon card case.The CF & DF scales are folded at π.

The third rule is a “Universal I” ten inch slide rule. Its scales are:LU,S,A{B,C1,C}D,T,LL. It is missing its cursor. It has a black card case.

A five inch Unique Log Log slide rule in its maroon card box. The scales are: LU,A{B,C1,C}D,LL. There are trig tables on the reverse.

A five inch Unique Universal I slide rule. The scales are: LU,S,A{B,C1,C}D,T,LL. It has tables of useful equivalents and properties of materials on the reverse.

A ten inch Unique “Commercial” slide rule. The scales are: H,K,M{N,R,C}D,U,V. It has conversion tables on the reverse and has a maroon card case.

A ten inch Unique “Brighton” slide rule. The scales are: K,A{B,C1,C}D,L,P//{LL1,LL2,LL3}//S,T on edge. It has a blue card case. There are formulae on the reverse. This was Unique’s most complex rule and was aimed at the European market.

A five inch Unique “Dualistic High Speed” slide rule. The scales are: P1,D2{C2,Q1,Q2,C1}D1,P2. C1 & D1 are the usual C & D scales. C2 & D2 are folded at root 10. The P and Q scales are ten inch scales divided at π. There are tables of material properties on the reverse.

This is a late ten inch version of the Unique Universal One slide rule with a vinyl wallet. The scales are the same as on the other two Universal I rules in the collection. It has English/Metric conversion factors on the reverse.

Concrete Volume Computer made by Unique for Trent Ready Mixed Concrete Ltd whose locations are on the back. It has four scales, for: thickness; height or width; length; volume. Instructions are printed in the middle of the slide. Imperial measurements. These did not have a cursor.

Unique Universal 10” slide rule. It has a replacement, probably home-made, plastic and wire cursor. Same scales as the Universal I at the top of the page: LL2, S,A{B,C1,C}D,T,LL3 in standard notation.

Unique Universal II 10” slide rule. It has a black card case. Scales are: LL2,A{B,S,T,C}D,LL3.

Unique Navigational 10” slide rule. It has a fawn card case. The information on the reverse relates to air navigation. Scales are: 1:500000\S1,A{B,S2,T2,C}D,T1\1:1000000

Unique ten - twenty 10” slide rule. It has a black card case. Usual Unique construction. The scales sre double length scales in the place usually occupied by the A/B and C/D scales to give 20” rule precision on a 10” rule. Either side of the sliding scales are scales giving the squares of the numbers on the scales they are adjacent to,.There are tables on the back of the rule.

Unique J180 plastic 7” scale length closed frame slide rule. Scales are: K,A{B,C1,C}D,S,T,ST.

“Harfield” Weight Calculator made by Unique. Closed frame wood with celluloid covered paper scales and plastic cursor. Black card case. Made for George W Mancell (London) Ltd. These were made for a number of different firms. Scales are: length{lbs per foot, no of bars}total weight.

Unique Legible 10” slide rule, celluloid over paper scales on wood body. Plastic cursor. Scales are A{B,C}D. It has a vinyl wallet.

The reverse of a similar concrete volume computer made for the Sussex Ready Mixed Concrete Co Ltd.

The metric version of the concrete volume computer, made for RMC Readymix.

Unique Jiffy 4” slide rule, usual Unique construction. Scales are A{B,C1,C}D,K. These tiny rules are not named or branded but are known to be made by Unique. The white plastic inset into the reverse is plain. These rules were supplied in a clear vinyl case.

Ratcliffe’s Spring Calculating Slide Rule made by Unique for F S Ratcliffe (Rochdale) Ltd who were specialist spring makers. It is made in the usual Unique way except that it has two slides. The upper slide is used to calculate the stress in the spring and the lower to calculate the spring rate. It has a red card case and a sheet of instructions.

Unique Dualistic ten inch slide rule with reversible slide. It has a black card case. Scales are: cm\P1,D2{C2,Q1,Q2,C1}D1,P2\in//{LL1,LL2,LL3}. These are explained below the 5” Dualistic near the top of the page.

Slide Rule for Tube Making and Deep Drawing made for Tube Investments by Unique. The scales are: mm,R1{R2,TH,C}D,WT. It has a card case.

Unique Monetary slide rule. It has a blue card case. The scales are M2,M1{B,C}D,M3. The M scales are British £sd scales. There are instructions on the back.

The metric version of the Harfield Weight Calculator made for George Robinson & Son Ltd, Steel Stockholders, London. It has a vinyl wallet of the standard Unique type but with George Robinson on it in large print.

A ten inch Unique Log Log slide rule with celluloid covered paper scales on wood. This is a variant of the Log Log slide rule shown at the top of the page with a metal tensioning spring inserted into the wood stock. Scales are: LU,A{B,C}D,LL. It has tables of trig functions and formulae on the reverse. It has a black card case.

The late type of the ten inch Unique Log Log slide rules, still the celluloid covered paper scales on wood but with a more modern type face and late type cursor. The tables and formulae are the same as on earlier Log Log rules except for the type face. Scales are unchanged.

Another Unique Log Log slide rule. This 5” slide rule, unlike the 5” log log above, does not have a reciprocal scale. It has a black card case. The tables on the back are, however, the same.

A late version of the Unique Universal One slide rule with the five inch scale length. The scales are the same as on the other Universal One and Universal 1 slide rules shown above: LU,S,A{B,C1,C}D,T,LL where LU and LL are respectively LL2 and LL3 in the standard nomenclature.

A Unique Five-Ten slide rule. Its five inch scale length has the precision of a ten inch rule as the main scales are divided at mid-point between the upper and lower slide edges. The mantissa scale in the centre of the slide is similarly divided. The uppermost and lowermost scales on the stock give the squares of the main scale numbers. This five inch scale length mahogany, paper and celluloid rule has a black card case.

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