Before performing calculations, it is important to become familiar with the physical components of the Frederick Post Versalog Catalog No. 1460.
The Versalog 1460 is a precision duplex slide rule. Understanding the purpose of each component will make calculations faster, reduce errors and help you develop confidence with the instrument.
The Main Components
The Post Versalog 1460 consists of four primary components:
- The body.
- The slide.
- The cursor.
- The scales.
Each component has a specific purpose in the calculation process.
The Body
The body is the fixed outer frame of the slide rule.
The body contains the fixed scales and provides the reference position for calculations. The accuracy of the instrument depends on the precision of the markings and the alignment between the body, slide and cursor.
The body also provides the structural support that keeps the instrument straight and stable during use.
The Slide
The slide is the movable centre section of the instrument.
By moving the slide left or right, the user aligns logarithmic values to perform mathematical operations.
The movement of the slide represents mathematical addition or subtraction of logarithmic distances.
For multiplication:
log(a × b) = log(a) + log(b)
The slide rule performs this addition mechanically by positioning one number against another.
For division:
log(a ÷ b) = log(a) – log(b)
The slide is moved to represent this subtraction.
The Cursor
The cursor is the transparent moving indicator that travels along the length of the slide rule.
The cursor allows the user to accurately transfer values between scales.
The cursor contains a fine hairline, which is the actual reference point used for reading calculations.
The cursor is used for:
- Reading results.
- Aligning values between different scales.
- Transferring intermediate results.
- Improving accuracy when reading the instrument.
A properly adjusted cursor is essential for accurate calculations.
The Scales
The Versalog 1460 contains multiple scales, each designed for a specific type of calculation.
The most commonly used scales include:
C and D Scales
The C and D scales are the primary multiplication and division scales.
They are used for:
- Multiplication.
- Division.
- Proportional calculations.
Most beginners should learn these scales first.
CI Scale
The CI scale is the reciprocal version of the C scale.
It is marked in the opposite direction and allows certain calculations to be performed with fewer slide movements.
The CI scale is especially useful for:
- Division.
- Reciprocal calculations.
- Complex chained calculations.
A and B Scales
The A and B scales are square scales.
They are used for:
- Squares.
- Square roots.
- Calculations involving powers of two.
K Scale
The K scale is a cube scale.
It is used for:
- Cubes.
- Cube roots.
- Calculations involving powers of three.
L Scale
The L scale is a logarithmic scale used for reading common logarithms.
It provides a direct relationship between a number and its base-10 logarithm.
Trigonometric Scales
The Versalog 1460 includes specialised trigonometric scales for calculating:
- Sine.
- Tangent.
- Related angular functions.
These scales were particularly useful in engineering and scientific applications.
Log-Log Scales
The Log-Log scales allow calculations involving exponential functions.
They are used for:
- Powers with non-integer exponents.
- Exponential growth calculations.
- Decay calculations.
Duplex Design
One of the advantages of the Post Versalog 1460 is its duplex design.
Unlike a simple slide rule with scales on only one side, the Versalog 1460 provides additional scales on the reverse side of the instrument.
This allows advanced calculations without requiring a second instrument.
Caring for the Instrument
The Post Versalog 1460 is a precision measuring instrument and should be treated accordingly.
Recommended care:
- Keep the slide rule clean and dry.
- Avoid excessive force when moving the slide.
- Do not bend the body or slide.
- Protect the cursor from scratches.
- Store the instrument in its protective case when not in use.
A well-maintained slide rule can remain accurate and usable for many decades.
Continue Learning
The next step is learning how to identify and read the individual scales: