NEWSON: NORMAL FORMS OF PROJECTIVE TRANSFORMATIONS. Maye 
The coordinates of the two invariant points A and B are respec- 
tively (a,b,c) and (,,b,,c,); the directions of the two invariant 
lines Al and BI’ are determined by (p,q) and (p,,q,). k is the 
anharmonic ratio along the line AB; a is the characteristic constant 
along the line Al, and a, is that along Bl’. 
TYPE IV. 
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tas Dip Cy I Srna Cys «Tl Keble) ics a2 il Ra oy Steuea: 
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fommOn te fe \OhOwe f Ot Ge— pw ie. (Onequ=pi er 
—_. —k = = a 
| | r | 
X,Y, 2, 1 DAY ay! Senge fee Ae per E Na) 
fad CS laa wr scent ADC ek Alea D pw Cret| 
CaO) an ete ee Cre Ae (Craw a, beac. 
eae AG 2 sg rama tele Emer Tee Otie site Dette 
Xen > Se ee 9 
cat Ds 5 Grgaelr| 
Aube Ce | 
I I On DY ana 
= —ma + —a?-—+ha. 
2 ae " Be UV ZN | BC geaaiae ind 
dee ence ty tial Sb. wes Tr avi ba errr 
| | 
he Beira ina) a es a diqy: Dea Crane 
eae eae? Oks .pyag: oO ae Ome Clee. 
The coordinates of the two invariant points A and B are respec- 
tively (a,b,c) and (a,,b,,c,); the direction of the line Al is deter- 
mined by p and q; f determines the inclination of the fixed plane 
mtothe plane AB]. The anharmonic ratio along AB is given by 
k; m, h, and a have the same meanings as in type III of the plane. 
TYPE V. 
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21.. 10) s(t Zi |o) 4G i 
Pape decals Guin pi que 
Oe ORE Tt uO CO ak mek 
— a; 
meray pay, 20 I 
at 10) @ an | EI oy ee at 
Lae de, O VE P q oO 
lito Ok oe to Om iO! ati 
