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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
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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 ad justed 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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" . . . 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 al so 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.
Representative terms from entire chapter:
average speed
