368 
ON DR. WIENER’S MODEL OF A CUBIC SURFACE WITH 27 REAL LINES ; [521 
Equations calculated 
from the measure 
ments of the model. 
ABCD 
a = - 5-688 
EFGH 
a = + 5-688 
AEBF 
y= + 5-688 
BGFG 
x = — 5-688 
CDGH 
y= -5-688 
AEDH 
*= + 5-688 
«si 8 
II II 
o o 
a i 
* = 0 
y= 0 
* = 0 
y = 0 
* = - '780s - -187 
y — — ’4232;+ ‘406 
a. 2 
* = 4-250 
y ~ 2*812 
* = -4-625 
y = - 2-000 
X — — -654a- -656 
y — — -588a + -531 
a 3 
* = 3-062 
y — 3*875 
* = - 4-375 
y = -2-812 
* = — 2-912a — 2-959 
y — — -736a+ -752 
«4 
y— -0625 
a = -9375 
y= 2-937 
a = -2-969 
* = 1-024a+1-014 
y — — l"049a— -277 
a 5 
x = — 4-812 
y= 5-688 
= - 5-063 
* = 4-562 
x= -264a + -187 
y —— -104a + -219 
«6 
*=-1-313 
y= -8125 
* = 1-687 
y = - -375 
X — — 1 "61 la + -151 
y — — \ -438a + -288 
y - 5-500 
a = - 3-625 
y = - 4-656 
a = 3*437 
x = 0 
a = — 1 
b. 2 
* = 0 
a = — 1 
* = 0 
a = — 1 
* = - l-352a- -685 
y~ — 2"034a — "984 
b 3 
*= 3-750 
a =- 3-281 
* = — 3-812 
a = 2-313 
x — — -753a— -0315 
y = - -500a- -0315 
b.* 
x = 4-250 
y= 2-812 
* = - 4-313 
y = - 2-875 
y= 0 
a= + l 
b 5 
y = o 
a = 1 
y=o 
a = 1 
x = l-123a- -702 
y — — l’123a + -702 
be 
* = -5-688 
a = - 4*438 
y = -5-688 
a = 5-688 
I hence calculate the intersections: considering any two lines which ought to 
intersect, then projecting on the horizontal plane and calculating x, y the coordinates