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Physical ultrasonics
BOOK REVIEWS P h y s i c a l foundations of t e c h n i c a l a c o u s t i c s I. M a l e c k i
P e r g a m o n (1969), 752pp, £ 11 In his p r e f a c e the author points out that all a p p l i c a t i o n s of sound f i e l d s to, for e x a m p l e , c o m m u n i c a t i o n s , n o n - d e s t r u c tive t e s t i n g , c h e m i c a l e n g i n e e r i n g , g e o p h y s i c s o r m a r i n e navigation, r e s t on a c o m m o n foundation of a c o u s t i c t h e o r y . His a i m has b e e n to p r e s e n t this b a s i c t h e o r y in a logical way, s t a r t i n g with s i m p l e i d e a l i z e d c a s e s and p r o c e e d i n g gradually to the t r e a t m e n t of r e a l p h e n o m e n a . This i s not intended to be a handbook containing l i s t s of u n r e l a t e d f a c t s but a s y s t e m a t i c s t a t e m e n t of p h y s i c a l l a w s . It is an a m b i tious u n d e r t a k i n g and it is c l e a r that a g r e a t deal of work m u s t have gone into the p r e p a r a t i o n of the book. It contains little that is new, nor indeed i s any c l a i m o r o r i g i n a l i t y m a d e for it, but it c o l l e c t s t o g e t h e r m a t e r i a l which was p r e v i o u s l y s c a t t e r e d a m o n g a n u m b e r of d i f f e r e n t books and a r t i c l e s . On the whole, in s p i t e of c e r t a i n s h o r t c o m i n g s , It can be s a i d to have a c h i e v e d its p u r p o s e . It is t h e r e f o r e a g r e a t pity that it i s m a r r e d by e r r o r s of t r a n s l a t i o n . It is s u r p r i s i n g that an e x p e n s i v e book like this was' published without a m o r e c a r e f u l c h e c k of its text to e l i m i n a t e e r r o r s of g r a m m a r and t e r m i n o l o g y , p a r t i c u l a r l y as the author s e e fit to thank a c o l l a b o r a t o r f o r tidying up the E n g l i s h t r a n s l a t i o n ! M o s t of the m i s t a k e s a r e m e r e l y i r r i t a ting to the r e a d e r and a r e not likely to c a u s e m i s u n d e r s t a n d ings but t h e r e a r e s e v e r a l which a r e m o r e puzzling. T h e r e a r e r e p e a t e d r e f e r e n c e s to the a c o u s t i c s c a t t e r i n g c r o s s s e c t i o n of an jobect a s its ' d i a g o n a l ' . This is c e r t a i n l y not a n o r m a l t e r m and it i s h a r d to s e e how a w o r d which i s g e n e r a l l y u s e d to r e f e r to a g e o m e t r i c a l line could p o s s i b l y a c q u i r e the connotation of an a r e a . At one point t h e r e a p p e a r s to be s o m e confusion b e t w e e n ' m e s h ' and ' c h a i n ' a s applied to c i r c u i t a n a l y s i s and the w o r d ' h y d r o l o c a t i o n ' , although it can be g u e s s e d to apply to u n d e r w a t e r s o n a r , is not in c u r r e n t u s e in Englishl T h e r e a r e a l s o a few new ' w o r d ' like ' c l a s s i f i c a l ' and ' v e r s o r ' , which do not o c c u r in the d i c t i o n a r y at all, and a few s e n t e n c e s , like t h o s e i m m e d i a t e l y following f i g u r e 4.25, which a r e unintelligible. Leqving a s i d e d e f e c t s of this kind, the 14 c h a p t e r s a r e well planned and follow each o t h e r in a logical o r d e r . A f t e r a b r i e f i n t r o d u c t i o n t h e r e is an adequate e x p o s i t i o n of c l a s s i c a l a c o u s t i c t h e o r y , dealing f i r s t with unbounded l o s s - f r e e liquids and s o l i d s and then with s i m p l e r e f l e c t i o n at plane or c o r r u g,ated i n t e r f a c e s b e t w e e n d i f f e r e n t m e d i a . C h a p t e r 5, which d e a l s with s u r f a c e s o u r c e s of a c o u s t i c w a v e s , is open to s o m e c r i t i c i s m . Some of this may be due again to poor t r a n s l a t i o n which had led to u n s a t i s f a c t o r y s t a t e m e n t s such a s 'If the vibrating s u r f a c e is a r i g i d body the s o u r c e is c a l l e d a p i s t o n - m e m b r a n e '. But, a p a r t f r o m ambiguous t e r minology, t h e r e i s a l s o a r e a l danger of u n c e r t a i n t y about w h e t h e r s o m e of the f o r m u l a e and d i a g r a m s apply to flexible m e m b r a n e s o r r i g i d p i s t o n s and w h e t h e r o r not the l a t t e r a r e s u p p o s e d to be s u r r o u n d e d by r i g i d b a f f l e s . Some explanation should a l s o be included to make it c l e a t that all the r e s u l t s r e a l l y only apply to i d e a l i z e d m o d e l s and that c a r e has to be taken in u s i n g t h e m in a t t e m p t s to s o l v e r e a l p r o b l e m s . C h a p t e r 6 is c o n c e r n e d with the t h e o r y of f i e l d p e r t u r b a t i o n a r o u n d an o b s t a c l e . As the author points out, this is a p r o b l e m which has not yet b e e n c o m p l e t e l y m a s t e r e d t h e o r e t i c a l l y and he gives a r e a s o n a b l e s u m m a r y of the l i t e r a t u r e a v a i l able. C h a p t e r s 7 and 8 go on to extend the b a s i c t h e o r y to r e a l liquids and s o l i d s . Then come t h r e e c h a p t e r s c o n c e r n e d with the v i b r a t i o n of m e c h a n i c a l s y s t e m s , in one or two d i m e n s i o n s , and with the i n t e r a c t i o n of s u c h s y s t e m s with acoustic fields. C h a p t e r s 12 and 13 deal r e s p e c t i v e l y with a c o u s t i c w a v e s in bounded s p a t i a l s y s t e m s (such a s c o n c e r t halls) and in extended s y s t e m s (such as the ocean) w h e r e r a y - p a t h r e f r a c tion e f f e c t s have to be taken into account. S u r p r i s i n g l y , no 194
ULTRASONICS July 1970
m e n t i o n i s m a d e of the s c a t t e r i n g of a c o u s t i c w a v e s by the s u r f a c e and bottom of the s e a and by inhomogeneity of the w a t e r i t s e l f . The final c h a p t e r is c o n c e r n e d with f i n i t e amplitude waves and v i b r a t i o n s . It is n e c e s s a r i l y l i m i t e d to a b r i e f s u m m a r y of this wide s u b j e c t . A good f e a t u r e of the book is that each c h a p t e r contains a n u m b e r of p r a c t i c a l p r o b l e m s which a r e fully w o r k e d out in the text. Each c h a p t e r is a l s o followed by a lengthy l i s t of p u b l i s h e d m a t e r i a l for f u r t h e r r e a d i n g , including many i t e m s f r o m R u s s i a n s o u r c e s . Although it is v e r y useful to have such i n f o r m a t i o n , it would be even m o r e helpful if s o m e i n d i cation could be given of the r e l a t i v e i m p o r t a n c e of the v a r i o u s r e f e r e n c e s , pointing out which a r e m o s t likely to be of a s s i s tance to the r e a d e r of the c h a p t e r in which they a r e quoted. This is p a r t i c u l a r l y so when many of the r e f e r e n c e s a r e in a language which may not be f a m i l i a r to the r e a d e r and which he would have to have t r a n s l a t e d . To s u m up, this i s a book which although it n e e d s s o m e r e vision and will n e e d to be r e a d with c a s e , does p e r f o r m e a useful function by b r i n g i n g t o g e t h e r a l a r g e amount of p r e viously published m a t e r i a l and p r e s e n t i n g it in the f o r m of a c o h e r e n t t h e o r y . The author not only t a k e s g r e a t c a r e to d e fine all the s y m b o l s u s e d in m a t h e m a t i c a l a n a l y s i s but he a l s o includes s e v e r a l l i s t s c o m p a r i n g the s y m b o l s u s e d by o t h e r a u t h o r s w h e r e they d i f f e r f r o m his and f r o m each o t h e r . V. G. Welsby
Physical ultrascvlcs B e y e r R . T . and L e t c h e r , S . V . A c a d e m i c P r e s s , New York and London (1969) 378pp, $18.50 The a u t h o r s c l a i m to p r e s e n t a m o d e r a t e l y advanced account of the p r e s e n t s t a t e of p h y s i c a l u l t r a s o n i c s f o r g r a d u a t e s and final y e a r u n d e r g r a d u a t e s . It could well be r e g a r d e d a s a s u m m a r y of the field c o v e r e d by the m o r e ambitious s e r i e s e d i t e d by W. P. Mason on ' P h y s i c a l A c o u s t i c s - - P r i n c i p l e s and M e t h o d s ' . The work d e a l s , in a c o n c i s e m a n n e r , with the mainly t h e o r e t i c a l a s p e c t s of the s u b j e c t and contains b r i e f d i s c u s s i o n s of the r e l a t e d e x p e r i m e n t a l findings. Detailed s t e p s in the a n a l y s e s a r e often left f o r the r e a d e r to work out for h i m s e l f . This should p r e s e n t little difficulty f o r one who i s well v e r s e d in the f u n d a m e n t a l s of p h y s i c s . N u m e r o u s r e f e r e n c e s a r e given and t h e r e i s a w e l l - p r e p a r e d index. With i m p o r t a n t e x c e p t i o n s , e x p e r i m e n t a l d e t a i l s a r e o m i t t e d . The p e r s o n who r e q u i r e s i n f o r m a t i o n on p r a c t i c a l applications of u l t r a s o n i c s i s not c a t e r e d f o r . The opening c h a p t e r d e a l s b r i e f l y with the n e c e s s a r y fundamental c o n c e p t s ; the r e a d e r i s r e f e r r e d to s t a n d a r d w o r k s on a c o u s t i c s f o r m o r e d e t a i l e d t r e a t m e n t s . The a p p r o a c h i s good and i s spoiled only by an e r r o r , p e r p e t u a t e d by a n u m b e r of a u t h o r s , in the t r e a t m e n t of the plane p i s t o n in an unbounded m e d i u m in which is given an i n c o r r e c t r e l a t i o n s h i p between the axial i n t e n s i t y and the d i s t a n c e f r o m the piston s u r f a c e . The next c h a p t e r , again s h o r t , s u m m a r i z e s the p r i n c i p l e s and p r o p e r t i e s of u l t r a s o n i c s o u r c e s and d e a l s with the p r o b l e m s of bonding. It contains a useful s e c t i o n on the p r e p a r a t i o n of thin f i l m c a d m i u m sulphide t r a n s d u c e r s . A t h i r d c h a p t e r , a l s o b r i e f , p r o v i d e s a s u r v e y of the p r i n c i p a l m e t h o d s of d e tection and m e a s u r e m e n t , c o n c e n t r a t i n g on the optical and pulse techniques. The bulk of the book .contains, in about 300 pages, an account of the p r i n c i p l e s of p r o p a g a t i o n in all t y p e s of media. The s e c t i o n on g a s e s c o v e r s , in s o m e 30 pages, the c l a s s i c a l t h e o r i e s of a b s o r p t i o n and a l s o r e l a x a t i o n p r o c e s s e s , including multiple r e l a x a t i o n s . The t r e a t m e n t f o r liquids i s m o r e s u b stantial, in view of the r a p i d d e v e l o p m e n t s made r e c e n t l y in the t h e o r i e s of liquids. It e m b r a c e s p r o p a g a t i o n in pure liquids, liquid m i x t u r e s , e l e c t r o l y t e s , v i s c o e l a s t i c s u b s t a n c e s , and liquid h e l i u m . A c h a p t e r on n o n - l i n e a r a c o u s t i c s , with a c c o u n t s of wave d i s t o r t i o n s t r e a m i n g , and cavitation, then follows. The c h a p t e r s on s o l i d - s t a t e a c o u s t i c s , which occupy
about two fifths of the book, deal with phenomena such as phonou-phonon interactions, third order elastic constants, dislocation damping and spin phonon interactions. The last named topic includes a substantial account of recent work on acoustic nuclear magnetic and paramagnettc resonances. The final chapter covers electron-phonon interactions in both metals and semi-conductors.
Conversion charts for Imperial and Metric quantities A. P a r r i s h London Iliffe Books Ltd (1969) 35pp, 10s
Butterworth and Co (Publishers) Ltd (1968) 25pp, 5s
These tables for conversion to International System units should be very useful for ULTRASONICS authors as SI units are employed throuhout the journal. To overcome the confusion caused by proliferation of units, technical metric (MKSA-gravitational) units are being phased out. The tables facilitate conversion of these units into SI. Conversion factors ar e resolved into a dimensionless number less than 10 and an appropriate power of 10 and presented in chart form. A series of 2-cycle logarithmic scales give the dimensionless numbers up to 10 for the factors relevant to ttte units of a quantity. Scales are positioned such that related numbers can be read of on horizontal lines across the scales. Accuracy is comparable with a normal slide rule.
The International System of units (SI) has been adopted by some thirty countries as the only legally acceptable c l a ssi fication of measurement of physical quantities. Other systems are being phased out. ULTRASONICS has made the change to SI and so recommends this handy booklet to its authors--and anyone else who need to know about International System units.
There are conversion charts for force, p r e s s u r e and str e s s , energy, specific energy, calorific value, specific heat capacity, thermal conductivity, density of heat flow-rate, thermal conductance, viscosity, thermal diffusion coefficient, Reynold's number, volume flow-rate and mass flow-rate. British Standard symbols and conversion units are used throughout.
Mary N. Davis
Mary N. Davis.
The work, which is completely up-to-date, presents a wellbalanced account of the subject and should prove to be of great value to the graduate physicist. The final year undergraduate, however, may find it somewhat heavy going. Jack Blitz BI and metrtcation conversion tables G. Socrates and L. J. Sapper
LETTERS TO THE EDITOR II
I
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Sir, The report of the Second International Conference on Medical Physics in ULTRASONICS January 1970 r e f e r s to our paper on Pulsatile Eeho-encephaiography and contains a number of inaccuracies. Pulsatile echo-encephalography detects the variations in amplitude and range of echoes originating within the brain. These variations are caused by the a r r i v a l in the brain of the a r t e r i a l pulse wave and not as suggested by your correspondent by blood flow pulsat'i"ons in the skull bones. We have recorded echo amplitude and range pulsations and have shown that the majority have an a r t e r i a l type of wave form. Most of the interfaces, in a coronal plane which passes through the third ventricle, pulsate in range towards the c e r e brat mid-line following each heart beat. The effect of this inward movement of cerebral structures on the circulation of the cerebro-spinal fluid was discussed. We did not report on the behavtour of interfaces outside this Limited region of the brain.
display facility, which on the Aberdeen instrument has been further improved by presenting the measurement as a digital read-out. A. D. Christie Ultrasonics Unit Aberdeen Maternity Hospital Foresterhlll Aberdeen
Senior Ceramics Applications Engineer
J. K. Campbell, Kingston, Queen's University, Ontario, Canada.
-Editors note Our special correspondent to the 2nd International Conference on Medical Physics (Dr C. N. Smyth) r e g r e ts that he misinterpreted rids communication and is glad to see the e r r o r corrected.
Sir, In a recent article by Hall et al, (Ultrasonics, Vol 8, Nol (January 1970), reviewing the technique of fetal cephalometry, it is suggested that simultaneous display of A-scan and Section-scan may be a further useful modification. T h e Dtasonograph at Aberdeen Maternity Hospital was modified in such a way some time ago following the suggestion of Mr Hall and Mr Fleming that the m a r k e r dots be presented on both A-scan and Section-scan for the reasons described in their article. There is no doubt that the degree of measuring accuracy has been improved by having a dual
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ULTRASONICS July 1970
195
P e r g a m o n (1969), 752pp, £ 11 In his p r e f a c e the author points out that all a p p l i c a t i o n s of sound f i e l d s to, for e x a m p l e , c o m m u n i c a t i o n s , n o n - d e s t r u c tive t e s t i n g , c h e m i c a l e n g i n e e r i n g , g e o p h y s i c s o r m a r i n e navigation, r e s t on a c o m m o n foundation of a c o u s t i c t h e o r y . His a i m has b e e n to p r e s e n t this b a s i c t h e o r y in a logical way, s t a r t i n g with s i m p l e i d e a l i z e d c a s e s and p r o c e e d i n g gradually to the t r e a t m e n t of r e a l p h e n o m e n a . This i s not intended to be a handbook containing l i s t s of u n r e l a t e d f a c t s but a s y s t e m a t i c s t a t e m e n t of p h y s i c a l l a w s . It is an a m b i tious u n d e r t a k i n g and it is c l e a r that a g r e a t deal of work m u s t have gone into the p r e p a r a t i o n of the book. It contains little that is new, nor indeed i s any c l a i m o r o r i g i n a l i t y m a d e for it, but it c o l l e c t s t o g e t h e r m a t e r i a l which was p r e v i o u s l y s c a t t e r e d a m o n g a n u m b e r of d i f f e r e n t books and a r t i c l e s . On the whole, in s p i t e of c e r t a i n s h o r t c o m i n g s , It can be s a i d to have a c h i e v e d its p u r p o s e . It is t h e r e f o r e a g r e a t pity that it i s m a r r e d by e r r o r s of t r a n s l a t i o n . It is s u r p r i s i n g that an e x p e n s i v e book like this was' published without a m o r e c a r e f u l c h e c k of its text to e l i m i n a t e e r r o r s of g r a m m a r and t e r m i n o l o g y , p a r t i c u l a r l y as the author s e e fit to thank a c o l l a b o r a t o r f o r tidying up the E n g l i s h t r a n s l a t i o n ! M o s t of the m i s t a k e s a r e m e r e l y i r r i t a ting to the r e a d e r and a r e not likely to c a u s e m i s u n d e r s t a n d ings but t h e r e a r e s e v e r a l which a r e m o r e puzzling. T h e r e a r e r e p e a t e d r e f e r e n c e s to the a c o u s t i c s c a t t e r i n g c r o s s s e c t i o n of an jobect a s its ' d i a g o n a l ' . This is c e r t a i n l y not a n o r m a l t e r m and it i s h a r d to s e e how a w o r d which i s g e n e r a l l y u s e d to r e f e r to a g e o m e t r i c a l line could p o s s i b l y a c q u i r e the connotation of an a r e a . At one point t h e r e a p p e a r s to be s o m e confusion b e t w e e n ' m e s h ' and ' c h a i n ' a s applied to c i r c u i t a n a l y s i s and the w o r d ' h y d r o l o c a t i o n ' , although it can be g u e s s e d to apply to u n d e r w a t e r s o n a r , is not in c u r r e n t u s e in Englishl T h e r e a r e a l s o a few new ' w o r d ' like ' c l a s s i f i c a l ' and ' v e r s o r ' , which do not o c c u r in the d i c t i o n a r y at all, and a few s e n t e n c e s , like t h o s e i m m e d i a t e l y following f i g u r e 4.25, which a r e unintelligible. Leqving a s i d e d e f e c t s of this kind, the 14 c h a p t e r s a r e well planned and follow each o t h e r in a logical o r d e r . A f t e r a b r i e f i n t r o d u c t i o n t h e r e is an adequate e x p o s i t i o n of c l a s s i c a l a c o u s t i c t h e o r y , dealing f i r s t with unbounded l o s s - f r e e liquids and s o l i d s and then with s i m p l e r e f l e c t i o n at plane or c o r r u g,ated i n t e r f a c e s b e t w e e n d i f f e r e n t m e d i a . C h a p t e r 5, which d e a l s with s u r f a c e s o u r c e s of a c o u s t i c w a v e s , is open to s o m e c r i t i c i s m . Some of this may be due again to poor t r a n s l a t i o n which had led to u n s a t i s f a c t o r y s t a t e m e n t s such a s 'If the vibrating s u r f a c e is a r i g i d body the s o u r c e is c a l l e d a p i s t o n - m e m b r a n e '. But, a p a r t f r o m ambiguous t e r minology, t h e r e i s a l s o a r e a l danger of u n c e r t a i n t y about w h e t h e r s o m e of the f o r m u l a e and d i a g r a m s apply to flexible m e m b r a n e s o r r i g i d p i s t o n s and w h e t h e r o r not the l a t t e r a r e s u p p o s e d to be s u r r o u n d e d by r i g i d b a f f l e s . Some explanation should a l s o be included to make it c l e a t that all the r e s u l t s r e a l l y only apply to i d e a l i z e d m o d e l s and that c a r e has to be taken in u s i n g t h e m in a t t e m p t s to s o l v e r e a l p r o b l e m s . C h a p t e r 6 is c o n c e r n e d with the t h e o r y of f i e l d p e r t u r b a t i o n a r o u n d an o b s t a c l e . As the author points out, this is a p r o b l e m which has not yet b e e n c o m p l e t e l y m a s t e r e d t h e o r e t i c a l l y and he gives a r e a s o n a b l e s u m m a r y of the l i t e r a t u r e a v a i l able. C h a p t e r s 7 and 8 go on to extend the b a s i c t h e o r y to r e a l liquids and s o l i d s . Then come t h r e e c h a p t e r s c o n c e r n e d with the v i b r a t i o n of m e c h a n i c a l s y s t e m s , in one or two d i m e n s i o n s , and with the i n t e r a c t i o n of s u c h s y s t e m s with acoustic fields. C h a p t e r s 12 and 13 deal r e s p e c t i v e l y with a c o u s t i c w a v e s in bounded s p a t i a l s y s t e m s (such a s c o n c e r t halls) and in extended s y s t e m s (such as the ocean) w h e r e r a y - p a t h r e f r a c tion e f f e c t s have to be taken into account. S u r p r i s i n g l y , no 194
ULTRASONICS July 1970
m e n t i o n i s m a d e of the s c a t t e r i n g of a c o u s t i c w a v e s by the s u r f a c e and bottom of the s e a and by inhomogeneity of the w a t e r i t s e l f . The final c h a p t e r is c o n c e r n e d with f i n i t e amplitude waves and v i b r a t i o n s . It is n e c e s s a r i l y l i m i t e d to a b r i e f s u m m a r y of this wide s u b j e c t . A good f e a t u r e of the book is that each c h a p t e r contains a n u m b e r of p r a c t i c a l p r o b l e m s which a r e fully w o r k e d out in the text. Each c h a p t e r is a l s o followed by a lengthy l i s t of p u b l i s h e d m a t e r i a l for f u r t h e r r e a d i n g , including many i t e m s f r o m R u s s i a n s o u r c e s . Although it is v e r y useful to have such i n f o r m a t i o n , it would be even m o r e helpful if s o m e i n d i cation could be given of the r e l a t i v e i m p o r t a n c e of the v a r i o u s r e f e r e n c e s , pointing out which a r e m o s t likely to be of a s s i s tance to the r e a d e r of the c h a p t e r in which they a r e quoted. This is p a r t i c u l a r l y so when many of the r e f e r e n c e s a r e in a language which may not be f a m i l i a r to the r e a d e r and which he would have to have t r a n s l a t e d . To s u m up, this i s a book which although it n e e d s s o m e r e vision and will n e e d to be r e a d with c a s e , does p e r f o r m e a useful function by b r i n g i n g t o g e t h e r a l a r g e amount of p r e viously published m a t e r i a l and p r e s e n t i n g it in the f o r m of a c o h e r e n t t h e o r y . The author not only t a k e s g r e a t c a r e to d e fine all the s y m b o l s u s e d in m a t h e m a t i c a l a n a l y s i s but he a l s o includes s e v e r a l l i s t s c o m p a r i n g the s y m b o l s u s e d by o t h e r a u t h o r s w h e r e they d i f f e r f r o m his and f r o m each o t h e r . V. G. Welsby
Physical ultrascvlcs B e y e r R . T . and L e t c h e r , S . V . A c a d e m i c P r e s s , New York and London (1969) 378pp, $18.50 The a u t h o r s c l a i m to p r e s e n t a m o d e r a t e l y advanced account of the p r e s e n t s t a t e of p h y s i c a l u l t r a s o n i c s f o r g r a d u a t e s and final y e a r u n d e r g r a d u a t e s . It could well be r e g a r d e d a s a s u m m a r y of the field c o v e r e d by the m o r e ambitious s e r i e s e d i t e d by W. P. Mason on ' P h y s i c a l A c o u s t i c s - - P r i n c i p l e s and M e t h o d s ' . The work d e a l s , in a c o n c i s e m a n n e r , with the mainly t h e o r e t i c a l a s p e c t s of the s u b j e c t and contains b r i e f d i s c u s s i o n s of the r e l a t e d e x p e r i m e n t a l findings. Detailed s t e p s in the a n a l y s e s a r e often left f o r the r e a d e r to work out for h i m s e l f . This should p r e s e n t little difficulty f o r one who i s well v e r s e d in the f u n d a m e n t a l s of p h y s i c s . N u m e r o u s r e f e r e n c e s a r e given and t h e r e i s a w e l l - p r e p a r e d index. With i m p o r t a n t e x c e p t i o n s , e x p e r i m e n t a l d e t a i l s a r e o m i t t e d . The p e r s o n who r e q u i r e s i n f o r m a t i o n on p r a c t i c a l applications of u l t r a s o n i c s i s not c a t e r e d f o r . The opening c h a p t e r d e a l s b r i e f l y with the n e c e s s a r y fundamental c o n c e p t s ; the r e a d e r i s r e f e r r e d to s t a n d a r d w o r k s on a c o u s t i c s f o r m o r e d e t a i l e d t r e a t m e n t s . The a p p r o a c h i s good and i s spoiled only by an e r r o r , p e r p e t u a t e d by a n u m b e r of a u t h o r s , in the t r e a t m e n t of the plane p i s t o n in an unbounded m e d i u m in which is given an i n c o r r e c t r e l a t i o n s h i p between the axial i n t e n s i t y and the d i s t a n c e f r o m the piston s u r f a c e . The next c h a p t e r , again s h o r t , s u m m a r i z e s the p r i n c i p l e s and p r o p e r t i e s of u l t r a s o n i c s o u r c e s and d e a l s with the p r o b l e m s of bonding. It contains a useful s e c t i o n on the p r e p a r a t i o n of thin f i l m c a d m i u m sulphide t r a n s d u c e r s . A t h i r d c h a p t e r , a l s o b r i e f , p r o v i d e s a s u r v e y of the p r i n c i p a l m e t h o d s of d e tection and m e a s u r e m e n t , c o n c e n t r a t i n g on the optical and pulse techniques. The bulk of the book .contains, in about 300 pages, an account of the p r i n c i p l e s of p r o p a g a t i o n in all t y p e s of media. The s e c t i o n on g a s e s c o v e r s , in s o m e 30 pages, the c l a s s i c a l t h e o r i e s of a b s o r p t i o n and a l s o r e l a x a t i o n p r o c e s s e s , including multiple r e l a x a t i o n s . The t r e a t m e n t f o r liquids i s m o r e s u b stantial, in view of the r a p i d d e v e l o p m e n t s made r e c e n t l y in the t h e o r i e s of liquids. It e m b r a c e s p r o p a g a t i o n in pure liquids, liquid m i x t u r e s , e l e c t r o l y t e s , v i s c o e l a s t i c s u b s t a n c e s , and liquid h e l i u m . A c h a p t e r on n o n - l i n e a r a c o u s t i c s , with a c c o u n t s of wave d i s t o r t i o n s t r e a m i n g , and cavitation, then follows. The c h a p t e r s on s o l i d - s t a t e a c o u s t i c s , which occupy
about two fifths of the book, deal with phenomena such as phonou-phonon interactions, third order elastic constants, dislocation damping and spin phonon interactions. The last named topic includes a substantial account of recent work on acoustic nuclear magnetic and paramagnettc resonances. The final chapter covers electron-phonon interactions in both metals and semi-conductors.
Conversion charts for Imperial and Metric quantities A. P a r r i s h London Iliffe Books Ltd (1969) 35pp, 10s
Butterworth and Co (Publishers) Ltd (1968) 25pp, 5s
These tables for conversion to International System units should be very useful for ULTRASONICS authors as SI units are employed throuhout the journal. To overcome the confusion caused by proliferation of units, technical metric (MKSA-gravitational) units are being phased out. The tables facilitate conversion of these units into SI. Conversion factors ar e resolved into a dimensionless number less than 10 and an appropriate power of 10 and presented in chart form. A series of 2-cycle logarithmic scales give the dimensionless numbers up to 10 for the factors relevant to ttte units of a quantity. Scales are positioned such that related numbers can be read of on horizontal lines across the scales. Accuracy is comparable with a normal slide rule.
The International System of units (SI) has been adopted by some thirty countries as the only legally acceptable c l a ssi fication of measurement of physical quantities. Other systems are being phased out. ULTRASONICS has made the change to SI and so recommends this handy booklet to its authors--and anyone else who need to know about International System units.
There are conversion charts for force, p r e s s u r e and str e s s , energy, specific energy, calorific value, specific heat capacity, thermal conductivity, density of heat flow-rate, thermal conductance, viscosity, thermal diffusion coefficient, Reynold's number, volume flow-rate and mass flow-rate. British Standard symbols and conversion units are used throughout.
Mary N. Davis
Mary N. Davis.
The work, which is completely up-to-date, presents a wellbalanced account of the subject and should prove to be of great value to the graduate physicist. The final year undergraduate, however, may find it somewhat heavy going. Jack Blitz BI and metrtcation conversion tables G. Socrates and L. J. Sapper
LETTERS TO THE EDITOR II
I
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Sir, The report of the Second International Conference on Medical Physics in ULTRASONICS January 1970 r e f e r s to our paper on Pulsatile Eeho-encephaiography and contains a number of inaccuracies. Pulsatile echo-encephalography detects the variations in amplitude and range of echoes originating within the brain. These variations are caused by the a r r i v a l in the brain of the a r t e r i a l pulse wave and not as suggested by your correspondent by blood flow pulsat'i"ons in the skull bones. We have recorded echo amplitude and range pulsations and have shown that the majority have an a r t e r i a l type of wave form. Most of the interfaces, in a coronal plane which passes through the third ventricle, pulsate in range towards the c e r e brat mid-line following each heart beat. The effect of this inward movement of cerebral structures on the circulation of the cerebro-spinal fluid was discussed. We did not report on the behavtour of interfaces outside this Limited region of the brain.
display facility, which on the Aberdeen instrument has been further improved by presenting the measurement as a digital read-out. A. D. Christie Ultrasonics Unit Aberdeen Maternity Hospital Foresterhlll Aberdeen
Senior Ceramics Applications Engineer
J. K. Campbell, Kingston, Queen's University, Ontario, Canada.
-Editors note Our special correspondent to the 2nd International Conference on Medical Physics (Dr C. N. Smyth) r e g r e ts that he misinterpreted rids communication and is glad to see the e r r o r corrected.
Sir, In a recent article by Hall et al, (Ultrasonics, Vol 8, Nol (January 1970), reviewing the technique of fetal cephalometry, it is suggested that simultaneous display of A-scan and Section-scan may be a further useful modification. T h e Dtasonograph at Aberdeen Maternity Hospital was modified in such a way some time ago following the suggestion of Mr Hall and Mr Fleming that the m a r k e r dots be presented on both A-scan and Section-scan for the reasons described in their article. There is no doubt that the degree of measuring accuracy has been improved by having a dual
Required by leading manufacturer of Piezoelectric Ceramics. He will be technically responsible for the upgrading of Ceramic products into complete transducers and also for close liaison with customers at home and abroad. This is an opportunity to become an authority on Ceramic transducers and will suit an Engineer qualified to B.Sc. or H.N.C. standard with a minimum of 2 years' experience in transducer design in the cleaning, sonar or flaw detection fields. Salary according to experience. Very modern factory close to Solent and New Forest.
Apply in confidence to: Personnel Officer,
Brush Clevite Company Limited, "rhornhill, Southampton.
ULTRASONICS July 1970
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