HARDWICKE'S SCIENCE-GOSSIP. 



197 



entering the elvan (the granitic vein) it became more 

 rich, and while passing through that rock the ore 

 was found to be so abundant as to afford a consider- 

 able profit. After quitting the elvan in its descent, 

 and entering the slate beneath, on the south, the 

 lode became poor, and eventually the mine was 

 abandoned from the scarcity of ore, the amount of it 

 in the depths not repaying the cost of raising. The 

 width of the lode was from six to nine feet in the 

 slate above the elvan, increased in the latter to 

 twenty-five feet, and decreased in the slate beneath 

 to ten feet." (p. 778.) 



And now with regard to the metamorphic origin 

 of some granites. As before mentioned, some 

 granitic masses were once the reservoirs from which 

 volcanoes were fed. When this mass was in its 

 liquid state it was charged with highly heated water, 

 which, by its expansive force, exerted enormous 

 pressure upon the fluid mass, and tended to force 

 it upwards and outwards in all directions. Where a 

 point of less resistance occurred, there the fluid mass 

 would be forced, and might result in the opening out 

 of a passage to the surface, when the mass would be 

 poured out as lava, and a volcano formed. But 

 whether such a communication were established or 

 not, the granitic magma would be forced against the 

 surrounding rocks, and by its heat, pressure, and the 

 action of the water, more or less metamorphosed them. 

 This metamorphism must sometimes have proceeded 

 so far as to cause the absorption of parts of the sur- 

 rounding rock into the mass of the granite itself, and 

 by the mechanical and chemical re-arrangement and 

 alteration of adjacent parts of the rock, so have changed 

 them that they were converted into true granite. 

 As the distance from the main granitic mass was 

 increased the effect of metamorphism would diminish, 

 and from granite and gneiss we should expect to find 

 succeeding crystalline rocks, such as mica-schist, less 

 and less altered. Veins would also be forced through 

 the surrounding strata from the main mass, so that 

 igneous and metamorphic granite would be formed 

 at the same time. By subsequent denudation these 

 various rocks would be exposed to view, and we 

 should have presented to us a mass of granite, part of 

 which we see had a metamorphic origin, surrounded 

 by zones of metamorphosed strata, decreasing in 

 degree of alteration the farther they are separated 

 from the central mass, and here and there, the whole 

 metamorphosed series pierced by granitic veins of a 

 truly igneous origin. 



But the contact of granite with other rocks does 

 not, by any means, always result in the conversion 

 of parts of the latter into granite. In the case of 

 the Skiddaw Slates, to mention one instance, whilst 

 these have been metamorphosed by intrusive granite 

 and converted into mica-schist, spotted-schist, and 

 clastobte slate yet the junction of the mica-schist 

 with the granite is sharply marked, and " there is no 

 general transition from mica-schist into gneiss 



(proper) or from gneiss into granite." (J. Clifton 

 Ward, Q.J.G.S. vol. xxxii.) 



To conclude, we find that granite is a perfectly 

 crystalline rock, that has consolidated at a depth 

 below the surface of the earth, from a state of hydro- 

 igneous fusion and under enormous pressure, resulting 

 in part from the expansive force of the heated water, 

 and in part from the weight of the superincumbent 

 rock masses. That it is generally of igneous origin, 

 but sometimes parts of it, at least, have resulted from 

 the complete metamorphism of other rocks. 



AN ODD PAGE IN NATURE'S BOOK. 



By the Rev. John Crofts. 



"TT TALK up, walk up, ladies and gentlemen! 

 V V and see a green pussy-cat with a crimson 

 head and a purple back ! Walk up, I say ! Here 

 she is, sitting up, all alive, with her two tails over 

 her back, and quite ready to commence her per- 

 formance ! She has just jumped out of her skin, 

 which she is now going to make a meal of! En- 

 trance only one penny ! 



" Performance about to begin ! " 



If you saw a showman beating his drum on the 

 steps of a bright yellow caravan, and bawling out 

 these words every now and then at the top of his 

 voice, I dare say you would wonder what sort ot 

 "take in" the man had got inside. Of course you 

 would say there never was, and never could be such 

 a thing as a green cat with two tails and a crimson 

 head ; and as to its jumping out of its skin and eating 

 it — it was on the face of it impossible and absurd, a 

 regular " take in," and just a showman's way of 

 getting money. 



But wait a moment. Perhaps there are pussy-cats 

 that you have never seen, with strange habits that 

 you have never heard of. 



I remember, years ago, reading of a boa constrictor 

 in the Zoological Gardens that swallowed its blanket, 

 and I was much struck at the time with the thought 

 of what a very dry and unsavoury meal it must have 

 been. The blanket was given to it, of course, to 

 serve as bed clothes, and for the creature to lie in j 

 but after trying that arrangement for a time and 

 finding it unsatisfactory, I suppose the monster conned 

 the matter over in its wise serpent head, and came to 

 the conclusion that, as its body was not comfortable 

 wrapped up in the blanket, it was worth trying how 

 it would feel with the blanket wrapped up in its 

 body. It was a happy thought, but alas ! it was not, 

 I believe, attended with very happy results. 



I remember too, as a very small boy, being a good 

 deal impressed upon hearing of a pig that (its owner 

 said) ate its head off ! and I wondered much how 

 such an extraordinary feat was accomplished. 



But it was not till the other day that I witnessed 



