Self-defeating innovation: less “tick marks” + more labelling = legibility but also less accuracy + table of trig conversion factors on back - read more ...

Table of decimal equivalents of fractions in well of stock & Trig tables on back

Early model made by Technical Supply Co - Trig tables on back

Self-defeating innovation: less “tick marks” + more labelling = legibility but also less accuracy + table of trig conversion factors on back - read more ...

Log Log type unhyphenated + no CI scale - Trig tables on back

Early model made by Technical Supply Co - Trig tables on back

For calculating areas of 2-dimensional figures or shapes in imperial square yards or square feet - bottom scales 2 parts of a single folded scale (folded @ 6 sq. feet)

Only Unique with Trig edge scales - despite unusual order of scales probably least unique Unique - table of decimal equivalents of fractions in well of stock & Trig formulas on back

Unconventional rule for merchants working pre-decimal & in imperial - conversion tables on back

Unusually the majority of the scales are calibrated for pre-decimal British £sd – a non-decimal currency that does not directly lend itself to a logarithmic scale.

Specially commissioned by Pioneer Concrete (UK) Ltd to calculate volume in cubic metres of concrete needed to fill conventionally shaped cavity (imperial or metric) - company name  on back

Copyrighted design for calculating (i) pre-decimal ​£-s-d & (ii) piece-rate pay - table of decimal equivalents of fractions in well of stock

Despite the misleading model name a deceptively simple to use calculator for working in imperial feet & inches (l x w) of 2 dimensional areas + total pre-decimal cost for a given price/square foot for timber, sheet metal, hardwood, plywood, etc.​

Unusual mixture of long-scales & folded (√10) scales - table of Decimal Equivalent of Fractions in the well & tables of properties of materials on back - see bigger sibling

Unusual mixture of long-scales & folded (√10) scales - table of Decimal Equivalent of Fractions in the well & table of properties of Trig Ratios on back - see smaller sibling 

Only known duplex model by Unique - name possibly derived from the profile of aluminium end braces - nonstandard scale layouts - simplex cursors glued back-to-back​

Unconventional layout (CF & DF & gauge points instead of W scale) - possibly made by Technical Supply Co. - Resistivity & Temperature Coefficient table on back

Extra narrow + imperial/metric conversion factors on back - model name possibly chosen for the US market - see smaller sibling  

Specially commissioned by UK specialist spring makers F S Ratcliffe (Rochdale) Ltd for helical tension & compression spring calculations - upper slide for stress & load/lower slide for spring rate + two tables & graph on back

Extra narrow with no Trig scales- table of decimal equivalents of fractions in well of stock + trig ratios on back - model name possibly chosen for the US market - see larger sibling  

Double-length scales giving 10” precision - table of Trig ratios on back - see larger sibling

For determining X-ray exposure times - developed (prov. patent 29187/45) by two esteemed radiographers: Friel & Sturdy - table of conversion factors in well, table of bone densities (?) on back of slide & table of absorption values on back

Specially commissioned by George Mancell (London) Ltd & extra narrow to calculate (imperial) total weight of steel bars (l x Lbs/ft) + tables of conversion factors & calculating aids on back

Specially commissioned by Harrison & Whitfield (Steel Stockbrokers) & extra narrow to calculate (imperial) total weight of steel bars (l x Lbs/ft) + tables of conversion factors & calculating aids on back

For calculating # of days between two dates in a year - table of decimal equivalents of fractions in well - conversion tables on back for pre-decimal Shillings & Pence to decimal £'s + Cwts & Quarters to Tons

Unbranded - provenance of name possibly from “done in a jiffy” citation on cover of instructions - could be most cloned slide rule as many versions exist & UNIQUE was not known as an OEM supplier

Stripped back version (fewer scales) of the Commercial - monetary scales (M1, M2 & M3) 3 parts of single folded scale (1d-£5000) – folded at 10/- & £50 - Table of decimal equivalents of fractions in well of stock

Apart from linear edge scales for measuring distances on maps it has no specific air navigation-related scales but unconventionally has S & T scales on front face = ideal layout for general calculations - air & wind speed conversions factors on back

Parallel line logo + overall longer & wider than standard Unique 10” model for chemical volumetric analytical calculations - tables of chemical atomic weights (A to Zr) in the well of the stock & a table atomic numbers for elements up to Nobelium on back

Specially commissioned by Metal Box Co. (MB) as in metal can production the overlap is a key integrity factor of the finished product ​- % butting = amount of overlap in imperial inches needed for a sound seam - another version was made by BH

Extra wide (3¼") ​body with mysterious non-standard  folded long-scales + 3 extra § scales in well & table of possible constants on back

Specially commissioened by Loewy Engineering Co. & extra wide with nomogram in the centre for separating Force and Torque + based on 1973 UK patent GB659754 (Antolij Mogiljanskij) - company give-away to buyers of Loewy equipment

Specially commissioned by Loewy Engineering Co. & extra wide with nomogram in the centre for separating Force and Torque + based on 1973 UK patent GB659754 (Antolij Mogiljanskij) - company give-away to buyers of Loewy equipment - given the style of text almost certainly a prototype version ​

Double-length scales giving 20” precision - table of decimal equivalents of fractions in well of stock - various conversion tables on back - see smaller sibling

1/5 set for calculating the Transmission Equivalent Resistance for 50 V. BALLAST in General Post Office (GPO) telephone cable design - overall longer & wider than standard 10” models - table of supplemental factors on back

2/5 set for calculating the Transmission Equivalent Resistance for 50 V. NON-BALLAST and SIEMENS No. 16 in General Post Office (GPO) telephone cable design - overall longer & wider than standard 10” models - table of supplemental factors on back

3/5 set for calculating the Transmission Equivalent Resistance for 40 V. C.B. in General Post Office (GPO) telephone cable design - overall longer & wider than standard 10” models - table of supplemental factors on back

4/5 set for calculating the Transmission Equivalent Resistance for 22 V. C.B in General Post Office (GPO) telephone cable design - overall longer & wider than standard 10” models - table of supplemental factors on back

5/5 set for calculating the Transmission Equivalent Resistance for all exchanges in General Post Office (GPO) telephone cable design - overall longer & wider than standard 10” models - table of supplemental factors on back

Extra wide & made for Tube Investments Ltd for drawing sheet metal through a dye to create tubes - various conversion tables & aids on back

Universal I = Trig scales on stock - tables of conversion factor/densities of metals/densities of non-mtal materiels on back

Parallel lines logo - tables of conversion factors on back

Tables of conversion factors/densities of metals/densities of non-mtal materiels on back

Universal II = Trig scales on slide - Trig formulaes on back

One of the earliest model’s - table of Trig values & formulas on back

On all Log-Log models LU unconventionally = Log Upper (LL2) & LL = Log Lower (LL3) - incl. CI scale + tables of properties of materials on back

Specially Commissioned by Manchester-based W. Wilkinson & unusually specifically designed for Anglo-American pre-decimal commodity market & incorporating scales for 2 different currencies - table of decimal equivalents of fractions in well of stock