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APPENDIX E 89
APPENDIX E
SIREN SOUNDS
Two of the most conspicuous features of the Channel I recording are the complete absence of siren sounds
for the first two minutes following the BRSW/WA conjectured shots and the clear presence of such siren sounds
for the next 36 seconds. Several sirens are heard in succession each in turn rising and falling in intensity as
would be the case if a motorcade were rapidly passing an open microphone. The siren sounds provide critical
tests of both the BRSW/WA scenario and that of the Committee.
The absence for two minutes of siren sounds, at a time when they should be heard, presents a serious
difficulty for the BRSW/WA hypotheses. According to that scenario, the motorcycle with the open microphone
was located in a precisely known position behind the President's car in the motorcade as it passed through
Dealey Plaza when the President was assassinated. Many witnesses agree that sirens were activated shortly after
the final shot and as the motorcade speeded up for its dash to Parkland Hospital. The complete absence of siren
sounds for two minutes is difficult to explain on this scenario, and the sounds, when they do appear do not seem
appropriate for a motorcycle in the motorcade, or even one catching up to the motorcade. If Officer McLain had
the open microphone, it is particularly surprising that he picked up no siren sounds while accompanying the
motorcade to the hospital but, at the same time, his microphone was so sensitive that it could pick up the
Channel II cross talk from a nearby vehicle.
The absence of siren sounds for two minutes is fully compatible with the Committee's scenario, which does
not require the open microphone to have been in the procession. James Bowles' hypothesis that the motorcycle
was at the Trade Mart can be supported by reasonable arguments but there is
use the print version of this publication as the authoritative version for attribution.
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APPENDIX E 90
no firm evidence for that location. Although the two-minute absence of the police sirens is obviously compatible
with the Committee's scenario, the timing of the appearance of the sirens requires careful examination. The cross
correlation between the “hold everything...” phrases on Channels I and II provides a relative timing of events that
can be tested for reasonableness with respect to the siren sounds. Absolute times were obtained by running
Channels I and II from the original Dictabelt and audograph disk, with the speeds adjusted to provide the correct
frequency for the 60 Hz hum on the original recordings. In this operation it was found that “hold everything...”
on Channel I begins 123 seconds before the siren sounds and on Channel II there is 64 seconds of continuous
recording between “...Go to the hospital...” and “hold everything...” which gives 187 seconds between “...Go to
the hospital...” and the beginning of the sirens. Since the distance from the assasssination site to the Trade Mart
is 2.273 miles, this corresponds to an average speed of 43.8 miles per hour if the trip began at the time of “Go to
the hospital”. At first consideration this appears to be surprisingly slow for a trip to the hospital, but there were
turns, traffic, a heavy car, Mrs. Kennedy and a Secret Service Agent crawling over the back of the car, and a
critically wounded passenger to slow the average speed. The speed we estimate is compatible with the testimony
of Agent Greer, the driver of the President's car, in volume II page 121 of the Warren Commission Report3: “...I
was getting through traffic and through streets as fast as I could get through... I would estimate that I must have
been doing between 40 and 50 at least 50 miles per hour at times. We might have been going as fast as 50 miles
an hour I am sure....”
If one assumes that on the streets and access ramps the average speed is 40 miles per hour, that the average
acceleration in a turn is 0.2g, and that the Zapruder film gives the time to leave Dealey Plaza, the above 187
seconds would require an average speed on the Stemmons Freeway of 58.5 miles per hour, which seems
reasonable in view of Agent Greer's testimony. It should be noted, however, that there is considerable
uncertainty as to the speeds attained, the location of the open microphone, and the time following the
assassination at which the “Go to the hospital” was broadcast. Although this discussion shows the compatibility
of the
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APPENDIX E 91
“...hold everything...” identification with the known firm data, it should not be misinterpreted as a proof of this
interpretation or as a reliable determination of the location of the vehicle with the open microphone, since there
is considerable uncertainty as to speed of the vehicle. There is also contradictory evidence about the time interval
between the assassination and the “Go to the hospital....” As this time is lengthened the average speed is reduced.
However, it should be noted that the assumption of a long time interval makes more acute the difficulty with the
BRSW/WA scenario discussed in Appendix C.
use the print version of this publication as the authoritative version for attribution.
