May 1, 1864] THE TECHNOLOGIST. 



OX GRANITE AND ITS USES. 435 



heavy hammers ; the sawings into slabs by great iron saws driven by 

 steam ; the protracted polishing by moving the slabs over each other ; 

 the employment of swift turning-lathes, and special iron tools, to give 

 the last touches to curved surfaces — include a great technological domain, 

 and involve a multitude of applications of science to art. The stone- 

 mason of this country, the hewer and carver of these rugged, intractable 

 stubborn rocks, is, as Hugh Miller as shown us by precept and example, 

 a very noble specimen of the industrial man, and all the more so that he 

 too often falls a sacrifice to his hard labour, and dies young in years, 

 having lived only long enough to carve his own tombstone. Let him be 

 thoughtfully regarded as one of the hardest-wrought of hard-working 

 men, whom industrial science hopes yet to save, by the substitution of 

 machinery for bodily labour, from that slow self-murder which is too 

 often inseparable from his calling. What the nature of his work is you 

 will best appreciate by the records of our lighthouses. Our works on 

 lighthouses are all delightful reading such as Snieaton's ' Record of the 

 Building of the Eddystone Lighthouse/ the elder Stevenson's ' Record of 

 the Building of the Bell Rock Light,' and his son Alan's very dramatic 

 and picturesque description of the ' Lighthouse of Skerryvore.' It is 

 largely built of granite, and the modes of quarrying and fashioning that 

 stone are incidentally but fully given in his work, and connected with 

 the striking story of the building of the great northern beacon. 



Turning aside from granite as a rock which we speak of as if it were 

 uniform in structure, we have now to look at it as an aggregate of 

 minerals. Its name signifies that it is. The word ' granite ' implies 

 made up of separate grains. There is no stone to which the name, as a 

 name, might not be given ; but it is specially applied to the one rock, 

 because its component grains are very different in colour and lustre, and 

 catch the eye of even the most casual observer. In the best known, the 

 most typical, and, as it were, leading granite (of which there are many 

 varieties), the component grains are of three different kinds. There are 

 never fewer than two ; in reality there are always more than even three, 

 but 'beyond three we find only rarely disseminated and irregularly 

 scattered grains. 



The first of the three grains which concern us most now are trans- 

 parent, often quite colourless, and very like glass. They consist of rock- 

 crystal, otherwise called quartz. 



The second are to appearance opaque, black, or rather dark-brown., 

 and possess a peculiar silvery or pearly glitter (in Latin, micare}, from 

 which power to glisten their constituent is named mica 



The third grains are opaque, resemble white marble, and are white, 

 cream-coloured, buff, flesh-coloured, or reel. Their material is called 

 felspar ; i.e., feld (German), or field spar, a spar abounding in the fields. 

 On the felspar the colour of granite depends. 



As regards size, they may be no larger than grains of sand or 

 sugar, or as large as currants. All may be about the same size, or one 



r p 2 



