B. TERRESTRIAL PHYSICS AND METEOROLOGY. 55 



of Gaul and Germany in the Roman times, we can not but 

 admit that there has been a great improvement since that 

 date. Thus we are told of winters when the Danube and 

 Rhine were frequently frozen over, and of the occurence of 

 the reindeer and moose in localities far south of their present 

 habitat. Ovid laments over the fearful severity of his place 

 of exile on the coast of Thrace, and refers to the occurrence 

 of white foxes there, and contemporaneous references corrob- 

 orate his statements. 



Mr. Howorth inquires whether, even within the prehistoric 

 period, the circumpolar climate may not have been very tem- 

 perate, when that of more southern latitudes was very se- 

 vere. We know, in fact, that during the miocene period 

 Greenland once possessed a climate not dissimilar to that of 

 the Eastern United States, as shown in the occurrence of 

 numerous species of trees of large size, some of them, like 

 our cypress, etc., absolutely identical with our forest vegeta- 

 tion of the present day. Mr. Howorth also refers to the gen- 

 eral impression among whalers that excessively severe win- 

 ters in the more temperate latitudes are accompanied by an 

 unusual degree of mildness in the more northern latitudes. 



This we accept as an augury in favor of Captain Hall's ex- 

 ploration, since the winter of 1871-72 was one of the sever- 

 est on record of late years ; and should Mr. Howorth's sug- 

 gestion be correct, the captain should have enjoyed an un- 

 usual freedom from snow and ice, permitting him to prosecute 

 his researches to great advantage. 12 A, June 13, 1872, 121. 



PALMIERl's LAW RESPECTING ATMOSPHERIC ELECTRICITY. 



Mr. George Forbes, in an article in Nature upon Professor 

 Palmieri's observatory on Mount Vesuvius, to which con- 

 stant reference has been made in the accounts of the recent 

 eruption of that mountain, mentions a law in regard to at- 

 mospheric electricity that Professor Palmieri has reached, as 

 the result of his observations for a quarter of a century in a 

 country where meteorological changes are very regular and 

 less capricious than in Great Britain. He enunciates this as 

 follows: If within a distance of about fifty miles there is no 

 shower of rain, hail, or snow, the electricity is always posi- 

 tive. The single exception is during the projection of ashes 

 from the crater of Vesuvius. 



