322 Intelligence and Miscellaneous Articles. 



with in the " Avicula-contorta" zone of other parts of Great Britain. 

 However, the right ramus of the lower jaw of an Ichthyosaurus was 

 found in the lowest bed, lying on the blue Keuper Marl. Two 

 interesting additions to the vertebrate fauna of this series are 

 Trematnsaurus Alberti, and Lepidotus Giebeli ? 



The author pointed out the correlation of these beds with those at 

 Aust Cliff and other well-known localities in England, and their 

 probable connexion with similar deposits in Ireland and on the con- 

 tinent; and he concluded by defining the surface-extent of this the 

 most northern English deposit of Hhaetic age as yet discovered. 



XLI. Intelligence and Miscellaneous Articles. 



NOTE ON THE ELECTRICAL CONDITION OF THE TERRESTRIAL 

 GLOBE. BY A. DE LA RIVE. 



TT is at present generally admitted that in the normal condition 

 ■*- the atmosphere is charged with positive electricity, and that this 

 electricity increases from the ground (where it is almost zero) to the 

 greatest heights which can be attained. The terrestrial globe, on 

 the contrary, is charged with negative electricity -, as is proved by a 

 variety of observations, direct and indirect ; it is, moreover, a con- 

 sequence of the presence of positive electricity in the atmosphere ; 

 for one of the electricities cannot manifest itself in the free state 

 without the appearance of an equal quantity of the other kind. 



At the place where the atmospheric air and the solid or liquid 

 surface of the terrestrial globe are in contact, there is a layer of air 

 in the neutral state, the two electricities neutralizing one another 

 there, seeing that the cause (probably subterranean) which disen- 

 gages them necessarily acts without interruption. This neutraliza- 

 tion is of course facilitated on plains above the sea by the moisture, 

 always more or less considerable, with which the layers of air in con- 

 tact with the soil are charged. This, however, is not the case on moun- 

 tains, and especially on the higher peaks ; the dryness of the air 

 must render the combination of the two electricities more difficult, 

 and enable the negative on the ground and the positive in the air to 

 acquire a tolerably energetic degree of tension. This is shown on 

 the one hand by the strong positive electricity which air has at these 

 great heights, and on the other hand by the attraction which the 

 mountains exert on the positive clouds of the atmosphere in virtue 

 of their negative electricity. 



Now, wdiat would take place if a metal plate, sunk in the ground 

 on the plain, were connected by means of a telegraphic wire with a 

 similar plate immersed in the soil of a high place ? If the negative 

 electricity with which the two places are unequally charged were in 

 an entirely statical condition, the metallic wire becoming an inte- 

 gral part of the conducting layer of air which separates them, no 

 dynamic phenomena would be observed. But there is a continuous 

 flow of the negative electricity of the soil towards the positive of the 

 air, which produces the neutral layer; it follows necessarily that 

 there is a downward transport of negative electricity, or, what 



