construction of breakwaters and harbours, light houses, docks, fortifications, foundations, and voussoirs of bridges. On the other hand, it is unsuited for fine sculpturing on account of its crystalline-granular structure and coarseness; so that when we require a material suited for the ornamental portions of an ecclesiastical or public edifice, we are obliged to have recourse to the less granular and softer materials which are to be found amongst the formations of limestone, sandstone, or dolomite. Mode of Formation. The igneous origin of granite was first demonstrated by the philosopher Hutton from actual observation, 1 and maintained by him against his rival Werner and his school during the celebrated controversy of ‘ the Neptunists ’ and ‘ the Vulcanists.’ But while nearly all physical geologists are agreed that granite has resulted from a state of igneous fusion in presence of vapour of water, and under a high degree of pressure, it has been demon strated by Professor Haughton, that there are two great classes under which probably all granites may be arranged, namely, metamorphic and eruptive. 2 1 Playfair’s Illustrations of tlie Huttonian Theory. Hutton, convinced in his own mind, from the crystalline structure of granite, that it had been formed by cooling from a state of igneous fusion, went in search of an illustration of his views amongst the mountains of Scotland ; and in Glen Tilt, to his great delight, discovered veins of granite traversing schistose rocks. 2 Journ. Geol. Soc. Lond. vols. xii. and xviii.