256 PROFESSOR CAYLEY ON CUBIC SURFACES. 
48. The diagram is 
Lines. 
oacnacw^QOii^watoiucaia cj ^ w u» h 
11= 
12— C 2 
bOI cl 
X 
i 
^1 C7« 
OJ 
X 
1^ 
12 
* 
• • 
• 
s 
. . 
• 
14 
• 
• 
15 
* 
• 
ie 
• 
• 
23 
# 
• • 
24 
* 
• 
. 
. 
Biradial planes, through 
• 
each pair of rays. 
§ 26 
15x2=30 
* 
• 
Pi 
* 
34 
* 
• • 
• 
• 
• 
• 
36 
* 
• 
* 
45 
* 
• • 
46 
• 
• 
* 
56 
* 
• • 
12.34.56 
. 
1 
) 
12.35. 46 
• 
12.36.45 
. . 
13.24.56 
. 
13.25.46 
. 
13.26.45 
. 
14.23.56 
15x1= 15 
. 
Planes each containing 
14.25.36 
o 
three mere lines. 
14.26.35 
. 
15.23.46 
• 
15.24.36 
. 
15.26.34 
. . 
16.23.45 
. . 
16.24.35 
• 
16.25.34 
30 45 
. 
g 
i 
g «'2 
p g 43 
^ o> ® 
§ ° t? 
ggrS 
Bi ° 
® p OQ 
O o' ^ 
p* £ 
49. Putting the equation of the surface in the form 
W(l, 1, 1, l+], m+-, n+±JX, Y, Y) 2 -f ^XYZ=0, 
y L 17Z Tfl J) 
