432 



THE GEOLOGIST. 



of tliose operations which have efFected the marked changes between 

 their actual and their original positions. 



Then follow the various propositions: — 1st. That most of these 

 leds must have descended very dowhj after their formation, heneath the level 

 at lohich they ivere deposited;^' and as an auxiliary to this proposition, 

 " That every area of long -continued de2mition must have heen an area of 

 slow continuous depression. That by far the greater ^^ortion of the 

 eartlvs surface which now constitutes dry land must have heen raised 

 ahove the level at lohich it ivas originally formed.'" 



In many cases, such descending movement must demonstrably have 

 preceded the ascending. For on reference to the preceding diagram 

 (fig. 8) it is easily seen that the edges of the strata which are, in a 

 geological sense, the lowest in the series, are actually found at the 

 greatest height above the sea-level, — often as much as 8,000 to 10,000 

 feet, and even to 15,000, as in the Himalaya mountains ; but these 

 same strata, if they have a sufiicieut aggregate thickness of strata 

 above them belonging to the higher part of the series, must, from 

 what has been already proved, have gradually descended from their 

 original position during the deposition of the superincumbent beds. 



Mr. Hopkins anticipates the very natural question: ''But what 

 physical causes can be assigned of sufficient mechanical energy to 

 produce these mighty movements?" and replies that modern volcanic 

 eruptions indicate the former existence of adequate power in the intu- 

 mescence of fluid lava produced by the expansion of elastic gases 

 within it. 



(To he continued.) 



POREIGK COIIEESPOITDEKCE. 



By He. T. L. Phipsost, of Paeis. 



Tyritifcroiis lignite ^ and its applications — A Diamond which has turned 

 out to he a Topaz—The metal Cerium and its comimwids — Waters of 

 the Day of Vtdcano at Santorino — Falmntology in Southern Russia — 

 Errata, 



At the last meeting of the Societe Impcriale d' Horticidture, at Paris, M. 

 Millot-Brule, an agriculturist, presented to the members of this insti- 

 tution a dark-coloured earth, which he had em.ployed with success, he 

 stated, against the attacks of grubs, snails, &c., in gardens or planta- 

 tions. By scattering a small quantity of this earth around any plant, 

 the approach of slugs, or the larva of insects, &c., was rendered im- 

 possible. This was proved by experiment before the meeting, by placing 

 some slugs and larva? of cockchafers upon a damp plate of glass and 

 surrounding them with a circle of the black earth, liot a single one 

 could make its escape, and pass out of the circle ; and when the earth 

 was sprinkled upon them, the animals soon died. Experiments were 

 also tried, -witli similar success, upon the cryptogamic vegetation which 

 constitutes the disease of the grape. Tines that had suffered remarkably 

 from the ravages of the Oidium Tuchri were restored to health when 



