The document describes two high accuracy measuring devices: the vernier caliper and micrometer. The vernier caliper contains scales to measure internal and external lengths in both inches and millimeters, as well as a depth probe. To take a measurement, you read the centimeter mark on the fixed scale and the millimeter mark that lines up on the vernier scale, then add any millimeters indicated on the vernier scale. The micrometer uses a rotating thimble to precisely measure thickness between fixed rods, reading the millimeter mark on the barrel and hundredths mark on the thimble, then adding them together. Both devices provide precise linear measurements down to hundredths of a millimeter.

1. High Accuracy Measuring Devices A. Vernier CaliperB. Microcaliper

2. A. Vernier CaliperThe Parts of Vernier Caliper

3. Inside jaws: Internal length (diameter) measurements are found by using this part.

4. Locking screw: blocks the instrument's movable parts.

5. Upper Scales: Vernier scale (inch) Rail (inch)

6. Lower Scales: Vernier scale (mm) Rail (mm)

7. Depth probe: The part used in order to find depth measurements Front end of the rail

8. Depth probe: The part used in order to find depth measurements Front end of the rail

9. 1. Inside jaws: Internal length measurements are found by using this part. 2. locking screw: This part blocks the instrument's movable parts in order to transfer between measurement methods easily.3. Vernier scale (inch)4. Rail (inch) 5. Depth probe: The part used in order to find depth measurements6. Front end of the rail7. Main scale (mm) 8. Vernier scale (mm) 9. Sliding Jaw10. Outside jaws: This part makes measuring external lengths possible.11. Fixed Jaw

10. Reading the Vernier Caliper

11. 1) Read the cm mark on the fixed scale to the left of the 0-mark on the vernier scale. (1 cm or 10mm on the fixed caliper)

12. 2. Find the mm mark on the fixed scale that is just to the left of the 0-mark on the vernier scale. (6mm or 0.6 cm on the fixed caliper)

13. 3. Look along the 20 marks on the vernier scale and the mm marks on the fixed scale, until you find the two that most nearly line up. (0.25mm on the vernier scale)

14. 4. To get the correct reading, simply add this found digit to your previous reading. (10mm + 6mm + 0.25mm= 16.25 mm)

16. 23.7 mm or 2.37 cm

18. 10.2 mm or 1.02 cm

20. 31.5 mm or 3.15 cm

22. 9.1 mm or 0.91 cm

24. 26.0 mm or 2.60 cm

26. 756.5 mm or75.65 cm

28. 756.8 mm or75.68 cm

30. Using the Micrometer Place the object whose length, diameter, or thickness is to be measured between the micrometer's measuring rods.

31. Using the Micrometer 2. Turn the thimbleuntil the spindlecontactsthe object to be measured. The rods should lightly touch the object between them but not clamp down on it.

32. Using the Micrometer 3. To apply a consistent pressure to the object, use the ratchet stop.

33. Using the Micrometer 4. Flip the locking lever to lock the measuring rods in place.

34. Using the Micrometer 5. Flip the locking lever to lock the measuring rods in place.

35. 1. The mm marks are above the horizontal line and the half-mm marks are below it.

36. 4.5 mm2. Read the value just exposed by the thimble on the central line of the cylinder. This value is in millimeters.

37. 4.5 mm0.13 mm3. Read the mark on the thimble aligned with the horizontal line on the barrel. This mark is in hundredths of millimeters.

38. 4.5 mm0.13 mm4. There are 50 such marks, each turn of the thimble corresponds to half a millimeter (the distance between the upward and downward marks on the cylinder central line).

39. 4.5 mm0.13 mm5. Add these values together. This is the measurement of the object between the measuring rods.

40. 4.5 mm0.13 mm4.5 mm + 0.13 mm = 4.63 mm

41. 5.5 mm0.17 mm5.5 mm + 0.17 mm = 5.67 mm

42. 3.5 mm0.17 mm3.5 mm + 0.17 mm = 3.67 mm

43. 4.5 mm0.17 mm4.5 mm + 0.17 mm = 4.67 mm

44. 18.5 mm + 0.40 mm = 18.90 mm