of Ritz's equation is Consider the diagram on the right, and note that , Plugging these expressions into Ritz's equation, we obtain the following Comparing to the original expression for Ampere's force law we obtain the coefficients in Ritz's equation From this we obtain the full expression of Ritz's electrodynamic equation with one unknown In a footnote at the end of Ritz's section on Gravitation ( English translation) the editor says, "Ritz used k = 6.4 to reconcile his formula (to calculate the angle of advancement of perihelion of planets per century) with the observed anomaly for Mercury (41") however recent data give 43.1", which leads to k = 7. Substituting this result into Ritz's formula yields exactly the general relativity formula." Using this same integer value for k in Ritz's electrodynamic equation we get: References and notes Further reading History of physics