( 256 ) 
Now we get (see MAXWELL 1873, blz. 129, I): ” 
dw dw dw ay? 
War Sd mn en =, IE 
dr dx & dy” - dz? 
sat = Cs 2 (Sy d dy dw 
2 de | \de ae dz ayers 
Let us put: 
dy? dy? dw? 
Rs ee A eee Pa pS Ee ey ee 
GY -nesrat 1m 
B (EUT fd Ee en 
DEE rasa +m 
dw? dy? dw? 
aN) af LA Vere arne iy 4 2 
ee Gy 5) Ln A Pe 
WVS beleg 4n(A+B 
En a (A + B) pyz = An (A + B) py 
dw dy 
ap STA t+ B)pe = 40 (A + B) ps: 
z de 
ee eee 
de dy 7 
then we get: 
dp, ae 
dy 
‘Pex | 
dz ' 
d dp 
Se ee 
| dx 
and so: 
Apex Apyx . dpa 
== ( ‘ d 
I Af go ay ee 
or as a surface integral on the surface, which encloses system I: 
a (res == Mm Pyz + N Per) ds 
and in the same way: 
Y =d Pay + M Pyy + 2 pzy) ds 
Zi = [Ure = M Pyz + N Pz) ds 
RE 
