A. B. Wood 169 
DONROO NN WOQOOOO09. POAOIOIOC eee080008 seceeess MO OT) 
nr edie 
- = rarhere es ————— _ ries @ 
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sorTom 
See Dw ESS OSCCOTCS 1COCCCOT OS 'COOFOEHS Ceereebe Saseseee 
430 KC/S. 189 KC/S. iss KC/S. 92 KC/S. $25 KC/6. 25-6 KC/S. 
@e00000s 2000 EdSS DEC8TT0GI DU OOSO00K teeeesegns 
ate —f == a —7F, SS SS SS 
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RUBBER SHEET 
: ! . iy ieee aS eer 
eee ee ———— 
@2eee 200002008: ceeoeene: baeceoososn 
189 KC/S. 60 KC/S. 92 Kc/S 25-0 c/s. 
430 KC/S. 
@eeneeee C8028 82GH8 190000008 ©90080800 
4. is 
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= = = RUBBER SHEET 
EX Ce ‘ON CONCRETE 
= lon 7 BOTTOM 
a VOL = 
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a pe : 
C0 00CSle: COSTES OOA POSSE COSS BESCETO0: 00080008 7h 
AGG tao Kc/S 180 Ke/S 92 KC/S. 52-5 Kc/s. 25-6 Kc/s. 
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: wey ee) > mbt aga Mk AON CONCRETE 
Anne eet eee Bs BOTTOM 
_ —— Ss. — 430 
F M P aa aN 7 
A Na Ona ee 
H 1 | Lv [Seu [B Won bole aaa) 
ial = : [——— 410 
eee eal : : See i EES 
toccessee Tocoseco 1eeeececese 1200S SSe 109088000 DOC28808O 
| 430 xcs (Bo Kc/s) 146 KC/S 92 KC/S. re 52-5 Kc/s. | sorBu 22% Tsunrace 
Boron SCE COMPARISON OF STEEL, CONCRETE, AND RUBBER-COVERED BOTTOMS “~~ 
'N FREQUENCY-RANGE 430 TO 25 KC/SEC. 
Fig. 10.8. B. and K. logarithmic records showing effect of varying the nature of 
the bottom and the frequency of the sound. 
either the steel or the concrete bottom is covered with a thin sheet (0.1 in.) of 
rubber. A further series of records using the concrete tank was made when the 
bottom was covered with fine sand Op, in. deep in an aluminum tray. These records 
confirmed that covering the steel sheet or the concrete bottom with thin sheet 
rubber was equivalent in general features to covering the bottom with fine well- 
wetted sand free from air inclusions. 
10.2.4. Wave Effects 
Neglecting the case of surface tension waves or ripples and considering only 
so-called gravity waves, we have two cases: 
Deep-water waves 
N= $T?/2n 
Shallow-water waves 
d = T(gh)? (A > h) 
where is the wavelength and T the periodic time of the waves, g¢ is the gravita- 
tional constant, and hf is the depth of water. In dealing with small-scale waves in 
the model tank, however, attention has been paid only to the scaling of wavelengths 
and wave heights. The time factor, involving T and g, has not been considered. 
