The Famous Blind Engineer of Belfast. 25 



it into the ground, to ascertain the comparative level of the two ; 

 to observe whether the one with the weight upon it would sink. 



" After the men had remained a considerable time upon it, we 

 found that it had not sunk in the slightest perceptible degree. 



" It then became a matter of calculation, if a six inch screw 

 would bear a ton at that depth, what a screw of foor foot diameter 

 would support, that being the size we thought it necessary to use. 

 It being eight times the diameter, that gives 64 times the surface ; 

 the circles being to each other as the squares of the diameter, the 

 four-foot screw would consequently carry at least 64 tons ; but 

 James Walker maintained it would support much more. 



" We give one single turn of the flange of the screw ; we have 

 found that most useful and practicable, because the holding power 

 depends upon the breadth of the disc, and not on the number of 

 turns, which only adds to the difficulty of getting itinto the ground. 



"The next lighthouse we erected was last summer (1844) in 

 Carrickfergus Bay ; it is intended to serve the double purpose of 

 a harbour light and a pilot station. It was lighted in November, 

 1844. The platform is 33 feet, and the diameter of the house 26, 

 the lantern 7^ or 8 feet. It cost ^1,300, including the lantern 

 and lighting apparatus. I was determined that Belfast should 

 have the benefit of the invention, and I did not work for profit. 

 That sum covered the whole expense of the materials and labour, 

 as it was not inconvenient to build, being near my own residence, 

 and it was rather ati amusement than anything else. It has been 

 well tried, having stood the storms of the last winter uninjured ; 

 and I may add that in tempestuous weather there are two heavy 

 boats suspended to it from davits which the pilots residing there 

 require for their use. These boats, belonging to the pilots, are 

 suspended from the platform at each corner by a strong crane like 

 the davit of a ship. 



" As the pilots require two good strong boats, and fearing they 

 may be swamped or stove in in stormy weather, they haul them up 

 and suspend them by these cranes out of the water, above the 

 reach of the highest wave, and then let them down, either the one 

 or the other to the lee side, when they want to go on board 

 vessels." 



