CHAP. IV. SMEATON'S LIGHTHOUSE ON THE EDDYSTONE. 29 



Thus, before Smeaton had proceeded very far, he had 

 come to the firm conviction that the new lighthouse 

 must be built of stone. Nevertheless, he resolved to 

 preserve the conical form of Kudyerd's building, but to 

 enlarge considerably the diameter of the foundation, 

 and thus increase the stability of the whole superstruc- 

 ture. The idea of the bole of a large spreading oak- 

 tree presented itself to his mind as the natural model 

 of a column, presenting probably the greatest possible 

 strength. Another point which he long and carefully 

 studied, was the best mode of bonding the blocks of 

 stone to the rock and to each other, in such a way 

 as that not only every individual piece, but the whole 

 fabric, should be rendered proof against external force. 

 Binding the blocks together by iron cramps was con- 

 sidered, but dismissed as insufficient, as well as im- 

 practicable. Then the process of dove-tailing occurred 

 to him a practice then generally applied to carpentry, 

 though scarcely as yet known in masonry. Still more 

 suitable for his purpose was the method which he had 

 observed adopted in fixing the kerbs along the London 

 footpaths, by which the long pieces or stretchers were 

 retained between the two headers or bond-pieces, whose 

 heads being cut dovetail-wise, adapted themselves to and 

 bound in the stretchers ; and the tye being as good at the 

 bottom as at the top, this arrangement, he conceived, was 

 the very best that could be devised for his purpose. 



From these beginnings he was readily led to think 

 that if the blocks themselves, both inside and out, were 

 all formed into large dovetails, they might be managed 

 so as mutually to lock one another together, being pri- 

 marily engrafted into the rock ; and in the round and 

 entire courses, along the top of the rock, they might all 

 proceed from and be locked to one large centre stone. 

 By thus rooting the foundations into the rock, and also 

 binding every stone by a similar dovetailing process 

 to every other stone in each course, upon which the sea 



