1. MECHANICAL MEASUREMENTS AND METROLOGY

2. STANDARDS OF MEASUREMENT
UNIT I
STANDARDS OF MEASUREMENT
INTRODUCTION
In 3000BC Royal cubit was defined as the length of the forearm of
the ruling Pharaoh, plus the breadth of his hand
In 16th century feet was created
In 18th century yard was declared by King Henry
In 19th century Meter was upgraded and wave lengths of light proved
a remarkable stable standard

3. STANDARDS OF THE PAST
People used to use parts of their body to determine the length of something.
The standard would be a part of the king’s anatomy.
The standard yard was the distance from the king’s nose to his outstretched arm

4. People would use their feet to measure distance
This is how the term foot came about.
Today the standard “foot” in the English system is
12 inches = 1 foot
machine

5. STANDARDS OF LENGTH: English Standards Metric Standards
English Standard: Master Standard (Instrument)
i.e. Imperial standard yard
Metric Standard : Master Standard (Instrument)
i.e. International Prototype meter

6. The English system is very confusing because it has so many different values

7. Scientists give the English system the thumbs down
Scientists needed an exact and uniform system of weights and measurements

8. America is the only country that still uses the old English system

9. IMPERIAL STANDARD YARD:
The British Imperial Standards were introduced in 1824, to systematise
the varying standards that had been used previously. Unfortunately
these standards were destroyed when the British Houses of Parliament
burned down in 1834, and new standards had to be established
The British Imperial Standards were introduced in 1824, to systematise
the varying standards that had been used previously. Unfortunately
these standards were destroyed when the British Houses of Parliament
burned down in 1834, and new standards had to be established

10. The British Imperial Standards were introduced in 1824, to systematise
the varying standards that had been used previously. Unfortunately
these standards were destroyed when the British Houses of Parliament
burned down in 1834, and new standards had to be established
This standard yard was kept with other standard measures in the basement at
Melbourne Observatory, to reduce the effects of changes in temperature. Even
so special calculations had to be made to allow for the expansion and
contraction of the metal in the standard yard.
The standard yard was set up in a machine fitted with microscopes, so that
exact comparisons could be made of two measures.

11. SCHEMATIC REPRESENTATION OF IMPERIAL STANDARD YARD

12. INTERNATIONAL STANDARD PROTOTYPE METER
The International Bureau of Weights and Measures established the Meter
as the linear measuring standard in the year The Meter is the distance
between the centre portions of two lines engraved on the polished surface
of a bar made of platinum(90%) iridium (10%) alloy having a unique
cross section. This bar is kept at 0C and under normal atmosphere pressure.

14. Figure : The 1875 W. & T. Avery Imperial Standard Yard in its original case.

18. A SLIP GAUGE SET

21. THANK YOU