Relation of Diamagnetic Polarity to Magnecrystallic Action. 125 



Donaghadee Tide, Table F, 



Difference of observed and calculated times of vanishing of diurnal 



tides at low water, expressed in lunar days. 



Age of lunar tide =5'i 2^ 



The agreement of the observed and calculated diurnal tides 

 shown in the preceding Tables is excellent. 

 [To be continued.] 



XV. On the relation of Diamagnetic Polarity to Magnecrystallic 

 Action. By John Tyndall, F.R.S. £fc.* 



IN a communication presented to the Koyal Society some weeks 

 ago, the fact of diamagnetic polarity was established in the 

 case of insulators, among which phosphorus, sulphur, calcareous 

 spar, statuary marble, heavy glass, nitre, and wax were comprised. 

 The demonstration was also extended to distilled water and other 

 liquids; and thus the conditions proposed by the opponents of 

 diamagnetic polarity for its rigorous demonstration were fulfilled. 

 The importance of the principle is demonstrated by the fruit- 

 fulness of its consequences ; for by it we obtain a clear insight of 

 phsenomena which, without it, would remain standing enigmas 

 in science, being connected by no known tie with the ordinary 

 laws of mechanics. Many of the phsenomena of magnecrystallic 

 action are of this paradoxical character. For the sake of those 

 who see no clear connexion between these phsenomena and the 

 other effects of magnetism, as well as for the sake of complete- 

 ness, I will here endeavour to indicate in a simple manner, and 

 from my own point of view, the bearing of the qixestion of polarity 

 upon that of magnecrystallic action. I will commence with the 

 elementary phsenomena, and select for illustration as I proceed, 

 * Cominiiiiicated by the Author. 



