THE CRISIS: A Telltale Tape Deepens Nixon's Dilemma

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definitively that there were nine recorded segments within the 18-minute portion was that none of these four was paired with a distinguishable "off' signature. They assume these "off signatures were fully or partly removed by the erase head in minutely overlapping operations. As Stockham explained it: "It is impossible to start recording and then start recording again without having stopped in between."

Thus the experts convincingly explained two of the key conclusions in their report: 1) "The erasures and buzz recordings were done in at least five, and perhaps as many as nine, separate and continuous segments" and 2) "Erasure and recording of each segment required hand operation of keyboard controls on the Uher 5000 machine."

Those findings completely ruled out the possibility, first raised in Sirica's court on Nov. 26 by White House Counsel J. Fred Buzhardt, that Rose Mary Woods had inadvertently caused the buzzed-out portion of the tape. She testified that she had been using a Uher 5000 to play back the June 20 tape in her White House office on Oct. 1 when she got a telephone call. She said that she reached for the telephone with one hand, mistakenly pushed the record button with the other and "must have" kept her foot on the pedal. But she also said her conversation lasted only about five minutes, and she refused to take responsibility for the rest of the buzz.

Buzz Section. The report does not mean that Miss Woods could not have done what she said she did. But such action would not produce the markings that the experts found on the obliterated section of tape. Even if she did make what she called her "terrible mistake," the erasure had to have been done in at least five other steps that could hardly have been accidental.

As for the source of the noise itself, a hum of varying loudness, the panel ruled out Miss Woods' typewriter and lamp—even though Counsel Buzhardt had said he had successfully simulated the sound on Miss Woods' recorder with them. Mark R. Weiss, vice president for acoustics research of Manhattan's Federal Scientific Corp., testified flatly that these could not have generated the noise. The panel used the lamp and typewriter, but "at no time," he said, "were we able to obtain a sound that resembled either by listening or by spectrum analysis the sound that was recorded on the tape."

The bearded and long-haired Weiss said instead that a defective component in Miss Woods' recorder had permitted a 60-cycles-per-second hum from the machine's electric cord to be picked up on the tape during recording. The experts reproduced a sound matching the buzz on the tape, but were unable to do so after replacing the component (a bridge rectifier). The sound level was affected by placement of a hand near the recorder, by noise on the line and by erratic functioning of the recorder. These tests further substantiated another finding of the panel: "The Uher 5000 recorder designated Government Exhibit No. 60 [the one Miss Woods used] probably produced the entire buzz section."

That, too, is a key finding, vastly narrowing the area of search for the person or persons who caused the erasure. While the panel qualified this conclusion with the word "probably" and used the term "almost surely" in a