I So SCIENTIFIC ILLUSTRATIONS [Int 



known to every one, is never missed in any year ; and in those 

 damp and cheerless summers, when even the white cabbage 

 butterfly is scarcely to be found, this creature may be seen in 

 every transient gleam, drying its wings and tripping from flower 

 to flower with animation and life, nearly the sole possessor of 

 the field and its sweets. It is a happy emblem of the insus- 

 ceptible man, who, whatever may be the sorrows. and agitations 

 of the period, is never dejected or depressed. Although the 

 gloom of death and wretchedness may be all around him, and 

 many of his fellow-creatures may be unable to face the pitiless 

 circumstances of the day, he is jaunty and jolly, vivacious and 

 able to enjoy his usual delights and avocations. Nature fortu- 

 nately gave him the brown butterfly temperament. J. 



The Principle of Interchange. 



Nature is against exclusiveness. It is part of her plan that 

 there shall be everywhere mutual giving and taking. You may 

 observe this even in the tides. The tidal currents are per- 

 petually shifting and redistributing the deposits along th,e sea- 

 bottom ; the Gulf Stream is as regularly transporting tropical 

 products to temperate regions; and the polar currents carry 

 with them icebergs and ice-floes laden with rocks and gravel, 

 which are dropped on the sea bottom as the ice melts away in 

 warmer latitudes. Eeciprocity is everywhere. AD. 



Interdicted Political Convictions. 



M. Fournet, in his description of the metalliferous gneiss near 

 Clermont, in Auvergne, states that all the minute fissures of 

 the rock are quite saturated with free carbonic acid gas, which 

 gas rises plentifully from the soil there and in many parts of 

 the surrounding country. The various elements of the gneiss, 

 with the exception of the quartz, are all softened, and new 

 combinations of the acid with lime, iron, and . manganese are 

 continually in progress. Another illustration of the power of 

 subterranean gases is afforded by the Stufas of St. Calogero, 

 situated in the largest of the Lipari islands. Here, according 

 to the description published by Hoffmann, horizontal strata of 



