Peterson 
the term ''cavitation" itself, and now Dr. Peterson seems to question 
it in his paper. That means that there is yet much work to be done. 
For my part Iam convinced that studies like that which was presented 
here can bring a new light on this problem, and I hope that they will 
pursued, 
DISCUSSION 
Luis Mazarredo 
Escuela T.S. de Ingenteros Navales 
Assoctacton de Investtgacton de la Construccton Naval 
Madrtd, Spatn 
I want to thank Dr. Peterson for showing the results of his 
very accurate experiments. Tests like these may give a real expe- 
rimental basis and avoid the contradictory results we sometimes 
found. This is for instance the case with the no influence of the sur- 
face state which has been shown. Though this might be predicted, 
since conditions in its crevices are permanent and there is no input 
(which would not be the case in a central propeller or in boiling) such 
a confirmation is wellcomed. Since positive results are still more 
interesting, may Iask Mr. Peterson wether he intends to perform 
tests, in the future, to check the magnitude of the influence of speed 
on this transient phenomenon ? 
REPLY TO DISCUSSION 
Frank B. Peterson 
Naval Ship Research and Development Center 
Bethesda, Maryland, U.S.A. 
In response to Mr. Johnsson's comments about his photogra- 
phic bubble measurements, all I can say is that in our work we tried 
to differentiate between the visual and the acoustic measurements. If 
we had in fact used the observations taken in high-speed photography 
then we would have said that inception had occurred earlier when there 
were more bubbles in the water. I think that might have been shown 
on one of the slides I presented. But in spite of that we still, appa- 
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