Lesson 11 Calibration

# Lesson 11 Calibration

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## Lesson 11 Calibration

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1. Lesson 11 Calibration

2. Engineers, turned first to parts of the body, for measuring instruments. However, this was not a positive fixed dimension or a standard. Measurements must be standard to mean the same thing to everyone

3. In 1793, the French government adopted a new system of standards called the metric system. In 1824, the English Parliament legalized a new standard yard which had been made in 1760. It was a brass bar containing a gold button near each end.

4. What is Calibration? • Act of comparing an instrument's measuring accuracy to a known standard • The process of adjusting an instrument, to establish a set of values for correct operation

5. MICROMETER

6. Notes Info about screw reqd

7. The cubit of Noah's time was the length of a man's forearm or the distance from the tip of the elbow to the end of his middle finger. Many times this was useful, because it was readily available, convenient, and couldn't be mislaid. However, it was not a positive fixed dimension or a standard. While the cubit is no longer used as a unit of measurement, there are many customary standards that originated in about the same way. Our foot-rule started out as the length of a man's foot. So, in the early days of history, the foot varied in length, sometimes as much as 3 or 4 inches. Once the ancients started using arms and feet for measuring distance, it was only natural that they also thought of using fingers, hands and legs. They also may have discovered that some surprising ratios existed in body measurements. What is now called an inch originally was the width of a man's thumb. It also was the length of the forefinger from the tip to the first joint. Twelve times that distance made a foot. Three times the length of the foot was the distance from the tip of a man's nose to the end of his outstretched arm. This distance very closely approximates what is called the yard. Two yards equaled a fathom which, thousands Going as far back in time as Noah's ark, the lack of a yardstick was not a serious drawback. Most measuring was done by one craftsman completing one job at a time, rather than assembling a number of articles piecemeal to be assembled later, it didn't make much difference how accurate the measuring sticks were or even how long they were. Generally, it doesn't make much difference how long is a mile, yard or inch or how heavy is a pound or ounce. What is really important is that everyone means the same thing when referring to each unit of measurement. Measurements must be standard to mean the same thing to everyone. of years ago, was the distance across a man's outstretched arms. Half a yard was the 18-inch cubit, and half a cubit was called a span, which was the distance across the hand from the tip of the thumb to the tip of the little finger when the fingers were spread out as far as possible. A hand was half a span. For thousands of years, this was the way people measured comparatively short distances. Each succeeding civilization added its it to mankind's knowledge, building an accumulation of measuring standards and techniques. Some contributed weight measures. Others showed us how to measure time. Still others gave us methods for