AECHITECTUEE. 



CHAPTER IV. 



LIGHTHOUSES. THE DOVETAIL. THE DAM. SUBTERRANEAN 

 DWELLINGS.-THE PYRAMID. M ORTAR, PAINT, AND VAR- 

 NISH. 



The Eddystone Lighthouse: its Position, and the Difficulties of building it. 

 Destruction of successive Lighthouses. Smeaton's Idea of Form borrowed 

 from the Tree-trunk. Mode of building. Rooting it into the Rock. 

 Principle of the Dovetail. Bones of the Human Skull, and their Articula- 

 tion. The Dam, and its Uses to Man. The Lock and the Water-mill. 

 Dam of the Beaver: its Objects and Mode of Con.struction. Popular Errors 

 with regard to the Dam. Subterranean Dwellings. The Indian Palace, 

 and its Use in Summer. Subterranean Dwellings in Kamschatka, and their 

 Use in Winter. The Wood or Horse Ant, and its double Dwelling. The 

 upper and lower Nests used according to the Amount of Warmth required. 

 Section of the Nest, and a Glimpse into its Interior. The Pyramid. 

 Derivation of its Name. Natural Objects from which the Form was derived. 

 Subaquatic Mortar or Cement, and its Use to Man. Subaquatic Cement 

 used by the Caddis, the Stickleback, the Terebella, the Sabella, the Serpula, 

 and others. Paint and Varnish, and their Utility to Man. Propolis as 

 used by the Hive Bee, and the Source whence it is obtained. 



TI7E now come to some points in Architecture which cannot 

 well be grouped together, and must therefore be treated 

 as Miscellanea. 



Our first example is one which was avowedly based upon 

 an imitation of Nature, namely, the celebrated Eddystone 

 Lighthouse, and we shall see that in two points first its form, 

 and next the mode in which the stones were fixed together 

 Nature had been closely followed by the architect. 



Unlike ordinary lighthouses, this edifice had to be con- 

 structed so as to endure the full force of waves as well as wind. 

 A few miles from the southern coasts of Devon and Cornwall 

 there is a rock which in former times greatly endangered the 

 ships which passed along the Channel. Several attempts were 

 made to build a lighthouse on this dangerous spot. Winstan- 

 ley's lighthouse, which was finished in 1700, was wholly swept 



