Precision Angle Measurement Instrument

The question asks to identify a precision instrument specifically designed for measuring angles with an accuracy level of 5 minutes ($5'$). Let's analyze the provided options to determine the correct tool.

Evaluating Measurement Tools for Angle Accuracy

Understanding the function of common precision measuring instruments is key to answering this question.

Dial Caliper Functionality

A Dial Caliper is primarily used for measuring linear dimensions such as length, width, diameter, and depth. It features a dial indicator for reading measurements easily. However, it is not designed for measuring angles.

Vernier Caliper Capabilities

A Vernier Caliper is a versatile tool for highly accurate linear measurements, including outside dimensions, inside dimensions, and depth. While some advanced Vernier calipers might incorporate features for basic angle measurement, their core design and primary application focus on linear measurements, and they typically do not offer the specific 5-minute accuracy for angles that the question requires.

Vernier Height Gauge Purpose

The Vernier Height Gauge is principally used on a surface plate for accurately measuring or marking vertical distances (heights). It can be utilized in setups involving angle measurement (e.g., with a sine bar), but it is not inherently an angle-measuring instrument itself.

Vernier Bevel Protractor Design and Use

A Vernier Bevel Protractor is a precision instrument purpose-built for measuring and setting angles. It consists of a base, a graduated circular scale, a pointer, and a movable radial blade (or vernier arm). The vernier scale allows for precise readings of angles, typically achieving an accuracy of 5 minutes ($5'$). This high accuracy makes it ideal for tasks requiring precise angle determination in mechanical engineering and machining.

Conclusion on Angle Measurement Accuracy

Comparing the instruments, the Vernier Bevel Protractor is the one specifically designed and commonly recognized for measuring angles to an accuracy of 5 minutes ($5'$). The other instruments listed have different primary functions related to linear or height measurements.