These temperatures are the endpoint temperatures of the new coordinate in degrees Celsius.

4. The ordinate © is now extended through the right-hand endpoint, as shown (see (6) ). 5. The next step is to prepare a linear scale (see (7) in the figure) which includes values between 32°C and 53°C and of such a length that the distance between 32.22°C and 51.67°C is equal to or slightly higher than the distance between points (2) and (3), the endpoints, on the temperature scale being constructed.

This requires graph paper or any paper with equal divisions, some luck, and some ingenuity.

6. This scale, (7), is then positioned as shown in the figure such that the point 32.22°C coincides with the left-hand endpoint (2), and the end 51.67°C intersects the line (6) at the location (8). 7. The new temperature scale is completed by constructing lines through significant divisions on level 7 and perpendicular to the new level (T) (see lines ® in the figure).

Both coordinates of a graph can be reconstructed for using different systems of units by using the procedure outlined in the preceding paragraphs. In most cases, this is considerably easier and quicker than constructing a completely new graph or trying to build a new scale on the real axis.

The number with the smallest amount of significant digits in this calculation is 778. Thus according to the rules of par. 4-2.3, the result should be rounded to three significant figures, as is done in Eq. 7-14. Hence the constant in the SI equation is approximately unity, and it is dimensionless and unitless. The original equation has a nonunity constant because mixed units were used, i.e., hours and seconds, and Btu and foot-pounds and use this fast converter.