1900. No. 5. ON PARTIAL DIFFERENTIAL EQUATIONS, ETC. AT 
where. 
A2F3 + E2F2H + D2 E3 + ACEF? + BDE?F =o. 
The corresponding system of total differential equations is 
AFdy + DEdx — EFds — 0 
(ZBF + E?D) dy — F(AF + CE) dx + E?Far — EF?dt =o. 
4. Letting Z=o, F=o, G + 0, we had the system 
ou 2 
een 
Ou ou ou 
mul de Se 
where 
AD — HG = BC. 
The corresponding system of total differential equations is 
Ady — Bdx + Gdt=o 
Dax — Cay + Gar =o. 
sa. Letting =o, G=o, E +0 and A + 0, we had the system 
Ou ar 
a 0 
ou Qu ou 
ou ou ou 
| AN 
where A, and A, are the roots of the quadratic 
421? — ABL + AC + EH — 0, 
and where 
DI (0), 
The corresponding system of total differential equations is 
A1, dx + Eds — Ady — 0 
Hdx + å, Ads + Adr = 0. 
