1. J. Moore, C. Davis, and M. Coplan,Building Scientific Apparatus: A Practical Guide to Design and Construction(Addison–Wesley, Redwood City, CA, 1989), p. 14.
2. A. I. H. Committee,Metals Handbook, 10th ed. (ASM International, Materials Park, OH, 1990), p. 837.
3. Permeability indicator No. 5150, manufactured by Severn Engineering Company, Annapolis, MD.
4. Other samples of bolts supplied by Kurt Lesker had lower permeabilities.
5. The curve was fit to the data points by smoothing with Mathcad’s (MathSoft, Cambridge, MA) supsmooth routine, and interpolating between points with a spline routine.