Marvels of the Universe 



121 



granite, etc.), together with flakes of mica, a substance familiar to many people owing to its uses 

 in the arts — in gas-fittings, electric insulators, etc. — where it is often miscalled talc. Now mica 

 is a highly flexible mineral (thus it is bent to form lamp-chimneys), and it was formerly supposed 

 that the flexibility of Itacolumite was due to the presence of this mineral in it. But many cases 

 occur of micaceous sandstones where no flexibility is exhibited, such as the well-known flagstones 

 used for street pavements ; while even in the Brazilian rock this peculiar property is only found in 

 a small part of the whole mass. Associated with the sandstone — or, more properly, " quartz- 

 schist " — of Brazil, are " mica-schists " which are far richer in mica, but quite inflexible. 



FlexibDit}- in the sandstone, then, seems to be due to the quartz and not to the mica. The grains 

 of quartz are angular and interlock at their junctions, but yet leave many empty interspaces. The 

 porous character of the rock allows movement in the spaces, while the hinge-like joints between the 

 particles hold them together in spite of the shifting to which they are subjected when a slab is bent. 

 If the reader clasp his hands together so that the fingers interlock, and then rub the palms together, 

 he ^vill illustrate roughly the action described. The Brazilian Itacolumite has an added interest 

 in being the probable source of the diamonds which are locally so abundant. 



PELORUS JACK 



BY F. T. BULLEN, F.R.G.S. 



It is ven.- refreshing to find in the midst of so many manufactured stories about the lesser-known 

 animals of our globe an item that, in spite of its romance and apparent fiction, is not only verifiable, 

 but has been verified by so many competent authorities that its truth is beyond all shadow of 

 reasonable doubt. Such a fact is found in the account of the Grampus which frequents the vicinity 



Flioto htj^ IMuir d: Hoodie. 



PELORUS JACK. 



The famous pilot of FrencK Pass. New Zealand, whicli lias been specially protected by Government. Altfiough com- 

 monly spoken of as a pi\ot-ffSh, it is really a Grampus, one of the wfiale family 



