At some point in the project, freeze the design / 35

Allocate resources as long as the cost of not knowing exceeds the cost of finding out / 35

Allocate sufficient resources to the weak link / 36

Solve problems by successive approximations / 38

I nduction / 65

The yield strength of a material is equal to a 0.02 percent offset on the stress-strain curve / 66

One gram of uranium gives one mega-watt day of energy / 66

Air has an ambient temeprature of 20 centigrade and a composition of 80 percent nitrogen and 20 percent oxygen / 67

A properly designed bolt should have at least one and one-half turns in the threads / 67

The cost of building construction scales as the price of meat / 67

Use a factor of safety of 1.2 for leaf springs / 68

Use a factor of safety of 1.5 for commercial airplanes / 69

Use a factor of safety of 2.0 for the bolts in the elevated walkway / 69

Quantify or express all variables in numbers / 70

Always give an answer / 71

Work at the margin of solvable problems / 72

Make small changes in the sota / 73

Always give yourself a chance to retreat / 75