I have decided to specialise in Blundell Rules Ltd and Blundell Harling as Blundell Harling are currently located in my home town of Weymouth. Also they are interesting for the wide variety of special purpose rules that they made, many of which are not currently shown on any of the slide rule web sites. I also have some links with former employees.

W H Smith Master Duplex A505 ten inch plastic slide rule. It has a PVC case and instruction booklet. The 23 scales are: LL01,LL02,LL03,A{B,L,C1,C}D,LL3,LL2,LL1//K,P,ST,DF{CF,C1F,C1,C}D,T,S. This is essentially the same rule as the Blundell Harling Super Duplex A505 and dates from the 1970s.

Blundell Harling Academy 804 Darmstadt 10” plastic slide rule. It is complete with blue plastic hard case and instruction booklet. Scales are: L,K,A{B,C1,C}D,P,S,T//{LL1,LL2,LL3}. Dates from the 1970s.

Blundell Harling 802 Log Log slide rule, simplex open frame, plastic with plastic cursor, dating from the 1970s. Scales are K,LL2,LL3,A{B,L,C1,C}D,S,T,ST.

Blundell Harling 803 Rietz slide rule, simplex open frame, plastic with plastic cursor, dating from the 1970s. Scales are L,K,A{B,C1,C}D,S,T,ST. The rule has a blue plastic case and a plastic card with tables and formulae on it. There is also an instruction booklet. I also have another with red writing & white end braces.

Blundell Harling 600 plastic, closed frame 5” slide rule. Scales are: cmS,T,A{B,C1,C}D,K,L. This is a promotional rule for BOS KALIS WESTMINSTER which is printed on the back of the rule and also the vinyl slip case. Late 1960s.

W H Smith Log Log Trig ten inch plastic open frame simplex slide rule made by Blundell Harling, based on their Academy 802 model. It has the standard 800 series blue plastic case and the usual W H Smith instruction booklet. The scales are: K,LL2,LL3,A{B,L,C1,C}D,S,T,ST.

Blundell Harling Super Duplex A505 ten inch plastic slide rule. It has a PVC case. The 23 scales are: LL01,LL02,LL03,A{B,L,C1,C}D,LL3,LL2,LL1//K,P,ST,DF{CF,C1F,C1,C}D,T,S. A version was also made branded for W H Smith as their Master Duplex A505, which can be seen below.

Blundell Harling 808 Accountants ten inch plastic slide rule. It is complete with blue plastic hard case and instruction booklet. Scales are: S,LL1,DF{CF,IL,IR,C}D,LL3,LL2. There are calendar scales on the reverse.

Blundell Harling S143-20 five inch open frame simplex plastic slide rule. It was sold as a school rule with just a polythene sleeve for protection. Scales are K,A{B,C1,C}D,L. The WH Smith 5” Simplified Rietz is the same basic rule with yellow accent stripes and a better wallet - see below.

Blundell Harling S150-20 plastic, open frame 5” slide rule. Scales are S,T,A{B,C1,C}D,K,L. It has a clear vinyl sleeve and instruction card. Intended for school use. Date c1970.

W H Smith Simplified Rietz plastic open frame simplex five inch slide rule, made by Blundell Harling. Scales are: K,A{B,C1,C}D,L. It has a PVC wallet and instruction booklet.

Blundell Harling S150-10 plastic, open frame 10” slide rule. Scales are S,T,A{B,C1,C}D,K,L. It has a clear/blue PVC sleeve. Intended for school use. Date c1970.

BHL PG54-2 Photographic Interpreters Slide Rule Mk II 7520-99-537-0544. This 10” duplex plastic rule was designed by the RAF; it was illustrated in the 1980 Blundell Harling catalogue. It has a grey and black vinyl case of the same type as used with other BHL ‘super duplex’ slide rules. The scales on the front face are: ground size (metres), ground size (feet), image size (millimetres), focal length (inches), focal length (millimetres), altitude (feet), designated on the right hand side z,y{x,w,v}u. On the right hand edge the y and x scales are also annotated A/C speed in knots and Cycling rate in cycles/s respectively. There are also various gauge points marked in red and green. The scales on the reverse are A{B,C1,ST,C}D,S,TA,TB. Along the top are the following gauge marks: m, ft, n mile, mile, km, UK gal, US gal, litre giving easy conversions using the cursor and B scale.

W H Smith Simplified Rietz 10” open frame simplex plastic slide rule. It has a PVC wallet, instruction booklet and card retail box. The scales are K,A{B,C1,C}D,L. This rule was based on the Blundell Harling S143-10 - see above.

Blundell Harling S143-10 slide rule, simplex open frame, plastic with plastic cursor, dating from the 1970s. Scales are K,A{B,C1,C}D,L. The rule has a clear plastic sleeve and simple instruction card.

This Blundell Harling Classmate 313 is also based on the S143-10 shown above. The scales are again: K,A{B,C1,C}D,L and it has yellow accent stripes and yellow end braces. It has a blue/clear vinyl sleeve that is becoming brittle. The scale length is only 9.5 inches and it is 3/4 inch shorter overall.

Blundell Harling Academy Duplex 904 ten inch plastic slide rule. It has a blue/clear PVC slip case and instruction booklet. Scales are: ST,A{B,C1,C}D,S,T//K,L,DF{CF,C1F,C}D,LL2,LL3

Blundell Harling Classmate 813 ten inch open frame plastic slide rule. It has a blue plastic case. Scales are: S,T,A{B,C1,C}D,K,L. Apart from the branding and type of case it is identical to the S150/10.

Blundell Harling S143/5 plastic 5” school slide rule. Scales are: K,A{B,C1,C}D. A beginner’s rule.

Blundell Harling S143/2 plastic 5” school slide rule. Scales are K,A{B,C1,C}D,L. Another beginner’s rule.

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