Correspondence

Errata. In my article in the May issue of spectrum, “Protecting Communication Systems from EMP Effects of Nuclear Explosions,” there is a significant error in the last line of the third complete paragraph on page 121. The quantity “1 million” should have been “100 000.” Also, in Detail A of the unnumbered illustration, the conduit or pipe should not continue on to the left since the purpose of the two shield wires is to protect cable that is not enclosed in conduit or pipe. In Fig. 1 curve d is for 0.01 in sheet copper with the joints soldered.