Chase. 1 258 [October. 



reacting gravitation of the air in the restoration of disturbed equi- 

 librium ; and, on the other hand, in water-spouts and tornadoes, the 

 flashes seem to follow, instead of preceding, the equalizing action of 

 aerial gravitation. We have never yet been able to measure the 

 electrical and gravitating momenta in such instances of violent com- 

 motioii ; but we can hardly doubt their exact equivalence, in view of 

 the well-established law, that " action and reaction are always equal 

 and in opposite directions." And in consideiation of such probable 

 equivalence, it does not seem unreasonable to quote them as standing 

 evidences of that long-desiderated link in the chain of kinetic unity, 

 lor the recognition of which the way has been partially prepared by 

 Henry's discovery of the tendency to equality of electric momenta, 

 and the correlation of intensity- and quantity-currents (Amer. Jour, 

 of Science [1], xxxviii, 218), Challis's hydrodynamic researches 

 (Phil. Mag., vol. i, sqq.), especially in their application to the expla- 

 nation of gravity as a necessary resultant of universal sethereal vibra- 

 tions (ibid. [4], xviii, 321, 443), Helmholtz's paper, "in which he 

 has pointed out that the lines of fluid motion are arranged according 

 to the same laws as the lines of magnetic force, the path of an elec- 

 tric current corresponding to a line of axes of those particles of the 

 fluid which are in a state of rotation" (Crelle's Journal for 1859, 

 referred to by Prof. Maxwell in Phil. Mag. [4], xxi, 348), Rankine's 

 " Summary of the Properties of Certain Stream Lines" (Phil. Mag., 

 Oct. 18G4, pp. 282-8), Norton's recent articles on " Molecular Phy- 

 sics" (Amer. Jour, of Science [2], vol. 38, sqq), and a variety of 

 other physical discussions, some of which I have already cited. 



The analogies which were pointed out by Gen. Sabine between 

 the thermal and magnetic curves (Hobarton Obs., I, xli; Toronto 

 Obs., I, xxxviii; St. Helena Obs., I, 38, &c. &c.), have been very 

 fully, and, generally speaking, satisfactorily discussed by Profs. 

 Norton (Amer. Jour, of Science [2], vols. 4, 8, 10, 19, 20) and 

 Secchi (Phil. Mag. [4], vols. 8, 9), the former directing his atten- 

 tion exclusively to the correspondence between the magnetic and 

 thermal variations, the latter to a hypothetical specific magnetism 

 resident in the sun. All of the reasoning of both these distinijuished 

 physicists can he applied, even more convincimjly, in siipport of the 

 hypothesis that simple (/ravitat ion-disturbances correspond to those 

 of magnetism, and many of the dijjiculties in the way of other theo- 

 ries disappear before such an application. 



Having established the coincidence and equivalence (with oppo- 

 site signs) of the magnetic and gravitating lines of force (Trans. 



