A vintage Russian KL-1 circular slide rule with a pocket watch type design with box (which is worn in places )outer scale makes it equivalent to a ca. 11.6 cm (4.6 inch) pocket linear rule. It is quite weighty and feels really well made and very tactile,and in excellent condition.
5 cms across
The KL-1 is intended for
performing trigonometric and mathematical operations:
1. Multiplication
2. Division
3. Squaring
4. Extraction of a square root.
5. Finding of trigonometric functions of a sine
6. Finding of trigonometric functions of a tangent
7. Finding inverse trigonometric functions.
8. Calculation of the area of a circle.
The circular slide rule consists of:
• Housing with two knobs,
• 2 dials (one of which revolves with the aid of the black
knob),
• 2 pointers (which revolve in unison with the aid of the
red knob), and a fixed indicator.
• The fixed indicator is on side 2, directly aligned with the
black knob
SIDE 1 : 3 scales on the fixed dial.
1. The outer scale - for basic calculating. It is the inverse
of the inner moveable scale on side 1 (equivalent to a
DI scale);
2. The middle scale S - for calculating the sines of angles;
3. The inner scale T - for calculating the tangents of angles
Please check all the photos as they do form part of the overall description and thanks for checking my other treasures from the past