MR. R. T. GLAZEBROOK ON PLANE WAVES IN A BIAXAL CRYSTAL. 349 
Let K be on the side of L remote from X. Experiment shows that this is the 
actual position of the wave normal in the case considered. 
Let 
KX=f 
.-. LK=KX—XL=f—1° 43' 10" 
. _ T7 . COS OL -jr . V 
cos 0= cos OL cos LK+ sm OL sm Lll cos y= cos 'v 
if 
tan X= tan OL cos y 
Substituting the values of 0 L and x 
A= 16° 17' 10" 
log ^^=1-0427912 
° cos A 
LK—A=t// —18° O' 20' 
Similarly 
where 
{y COS O L /t TV I \ / \ 
cos V =■ -— cos (Llv+A.) 
cos A v ' 
tan X'— tan O'L cos y 
A'=8° 17' 30" 
cos O'L - 
log-— 
° cos A 
: 1-3243204 
LK+X'=f+6° 34' 20" 
A table on the next page gives the values of i jj, the angle made by the incident 
wave normal with the normal to X; D-4 -i the deviation 4- the angle X Y; f the 
angle made by the wave normal in the crystal with the normal to X; and — /x being 
the reciprocal of the wave velocity. 
