1324 
"head-on" value. In fig. 12a, a', b, c, the ratio of F..... 
to F etnies is plotted as a function of F for O= 7-15, 
2000, 1.40, respectively. 
It may be that the extreme value of § “coincides 
with the "head-on" value for a particular strength F, of the 
incident shock. In that case "head-on" reflection gives higher. 
values of fF‘ than any oblique reflection for all stronger inci- 
dent shocks ( F < §,). Table 7 gives §, for Y= 7-15, 2.00, 1.40. 
"Extrome-Head-on" Equality 
é ¢ 
xX Fi (exter head) eo Ay (extr.head) “GS (extr.head) 
aI 
715 .6u245x(10) > 3563 31208 31208 
2.00 0.02345 9.082 35.80 35.80 
HefOu. O.L689 3.965 40°39 40°39 
Typical cases of material flow are shown in fig. l3a, 
b, c, For a given strongth Frat: of the incident shock I 
there is always one angle of incidence O,,4,;, for which the 
pressure and flow=-direction of the material behind the reflected 
snock R are identical with those corresponding to a "simple" 
Pare eauock intersection (cf. Section IV). For example, suppose 
the wall in fig. 7b is replaced by fluid having the same pres-=- 
sure as that of the neighboring fluid which had been in contact 
with the wall. This can be accomplished by having a third shock: 
M (cf. fig. 14) with its front normal to the contact-surface. 
> Se 
