Principles of the vernier scale

It would be possible to etch graduations 1/1000 inch (0.001) in. apart on a steel rule or sliding caliper. This enlarged illustration shows two graduated scales. The top scale has divisions which are 0.025 inches apart. The small sliding lower scale has 25 0.001 inch graduations which can divide any of the main scale divisions of 0.025 inch into 25 parts. When the first graduation marked “o�?on this small scale aligns with a graduation on the main scale, the last, or 25th will also align with a graduation on the main scale. Consequentl, the small 0.00