A particularly complete and attractive ARISTO Studio No. 0968 scientific duplex slide rule, made in Germany by ARISTO-Werke / Dennert & Pape, Hamburg, dating from approximately 1965.

The Studio 0968 was one of ARISTO’s more sophisticated professional slide rules, intended for engineers, scientists, students and technical draughtsmen. Unlike a basic Mannheim or Rietz rule, the Studio combines conventional logarithmic calculation with log-log exponential scales, trigonometric functions, powers, roots and folded scales.

The instrument is clearly marked “ARISTO – STUDIO” and “ARISTO Nr. 0968 – MADE IN GERMANY” and retains its original grey and ivory hard-plastic sliding case.

The two calculating faces

This is a true duplex slide rule, with scales on both sides of the body and on both sides of the movable central slide.

Log-log / exponential face:

LL01 – LL02 – LL03 – A [B – L – K – C] D – LL3 – LL2 – LL1

The individual markings represent:

• LL01, LL02 and LL03 – negative exponential/log-log scales for functions based on e
• A and B – square scales, x²
• L – common logarithm / mantissa scale, lg x
• K – cubic scale, x³
• C and D – principal logarithmic scales used for multiplication and division
• LL1, LL2 and LL3 – positive exponential scales, including e^0.01x, e^0.1x and e^x

The right-hand end of the rule carries ARISTO’s useful “self-documenting” mathematical notation, identifying the corresponding functions by symbols such as eˣ, x², lg x and x³.

Trigonometric / general calculation face:

T – ST – DF [CF – CIF – CI – C] D – P – S

These include:

• T – tangent scale, with complementary cotangent values
• ST – small-angle / arc scale
• DF and CF – folded π scales, allowing calculations to be made conveniently around π without shifting the slide
• CIF – inverse folded scale, 1/πx
• CI – inverse C scale, 1/x
• C and D – principal multiplication and division scales
• P – Pythagorean scale for √(1−x²)-type calculations
• S – sine scale, also carrying complementary cosine information

The scale ends are additionally printed with mathematical function legends including tan, arc, πx, 1/πx, 1/x, sin and cos.

This is not merely an ordinary ruler. It is an engineering preferred-number or “Normzahlen” scale, based on the internationally used Renard series R10, R20 and R40.

The preferred-number sequences include values such as:

1 – 1.25 – 1.6 – 2 – 2.5 – 3.15 – 4 – 5 – 6.3 – 8 – 10

Such preferred numbers were widely used in engineering and industrial standardisation for selecting sensible graduated dimensions, capacities, ratings and component sizes.

The yellow centre section also incorporates a mantissa scale, allowing logarithmic relationships to be read or estimated graphically. Along the upper edge is a conventional 0–25 cm metric ruler, while the lower edge incorporates the NZ-Maßstab / technical drawing scale, marked 1:2.5.

Condition

Very good vintage condition overall, especially considering its age.

The finely printed black and red graduations remain remarkably clear and legible. The transparent cursor and its metal fittings are present. There is normal age-related surface wear, some slight discolouration/yellowing to the pale plastics and accessories, and minor oxidation or age toning to some exposed metal parts.

The grey and ivory ARISTO-STUDIO hard case is also included and shows normal signs of age and storage.

No obvious major cracks or losses are visible in the photographs.

A very appealing and unusually complete example of a classic mid-1960s German precision calculating instrument, particularly interesting to collectors of slide rules, scientific instruments, engineering equipment, industrial design and the history of analogue computing.

Please study all photographs carefully, as they form an integral part of the description.