Electromagnetic  Gravitational 
(charge)  (mass) 
(volume charge density)  (volume mass density) 
(surface charge density)  (surface mass density) 
(line charge density)  (line mass density) 
(electric’s scalar potential)  (mass’s scalar potenctial) 
(magnetic vector potential)  (cogravitational vector potential) 
(convection current density)  (masscurrent density) 
(electric current)  (mass current) 
(magnetic dipole moment)  (cogravitational moment) 
E (electric field)  g (gravitational field) 
B (magnetic field)  K (cogravitational field) 
(permittivity of space) 

(permeability of space) 

 G (gravitational constant) 