TRANSACTIONS OF SECTION G. 681 



Three vertical shafts and one made in an oblique direction still remain ; the marks 

 on the hard rock show that the chisels employed in the cutting were an inch in 

 width. Another Roman work of still greater importance was the emissarium 

 at Lake Fucinus, planned hy Julius Csesar and carried into execution by Claudius. 

 This was a tunnel three miles in length, extending from the lake to the river Liris 

 (the modern Garigliano), one mile of it being driven through a mountain of cor- 

 nelian rising 3,000 feet above the lake. It employed 30,000 men for eleven years. 

 There are many perpendicular shafts for raising the rock to the surface and lateral 

 galleries for disposing of the spoil, so as to enable this large number of men to work 

 ■without interfering with each other. 



The supply of water to different cities of the ancients has been the motive for 

 the execution of the most stupendous works, which are almost numberless. It 

 will be sufficient for me to allude to the works constructed for the supply of the 

 city of Samos, about the time of Polycrates, B.C. 530, in which case a tunnel was 

 driven through a hill 150 fathoms high, for a length of seven furlongs. Its height 

 and width were each eight feet, and it conveyed the water from the river Ampelus 

 into the city. Herodotus tell us that the architect was Eupalinus, the son of 

 Naustrophus, a Megarian. Sir George Wilkinson, in a note on the text, mentions 

 the fact that a French traveller, M. Guerin, discovered one mouth of this tunnel to 

 the N.W. of the harbour of Samos, and cleared it from sand and stones to a dis- 

 tance of 540 paces. 



It is sometimes asserted that the ancients were ignorant of the hydrostatic law 

 that water finds its own level. This is not the case. Frontinus, who preceded 

 Agricola, the father-in-law of Tacitus, as Governor of Britain, and who was 

 Curator Aquarum in Rome under Nerva and Trajan, mentions in his book, ' De 

 Aquaeductibus Urbis Romae,' that in case of the fracture of an aqueduct, the 

 water could be dammed up at each side of the point of fracture, and carried over the 

 intervening space in leaden pipes. A great deal of the internal distribution of the 

 water in Rome was managed by leaden pipes under pressure. 



The aqueduct which Herod is said to have constructed for the supply of Jeru- 

 salem crossed a deep valley — near Rachel's Tomb — by means of a stone pipe 

 working under pressure. This work has been fully described by Mr. Telford 

 Macneill in the Report made by Sir John Macneill to the Committee for supplying 

 Jerusalem with water. The construction of this pipe is so remarkable that I shall 

 give Mr. Macneill's description in detail. It consists of great blocks of stone 

 through which holes 15 inches in diameter have been cut. One end of each block 

 has been hollowed out to a depth of 4^ inches, with a diameter of 24 inches ; 

 thus leaving a recess 4£ inches wide to form the socket of the pipe. The 

 other end has a projection of a size to fit a similar socket in the pipe which lies 

 next to it. This answers to the spigot of a modern cast-iron water-pipe. Both 

 socket and spigot are ground, so as to tit with great accuracy, and the joint is 

 made with cement, which has set as hard as the stone itself. The whole line of 

 these stone pipes is surrounded with rubble masonry. The pressure on the centre 

 of this very remarkable inverted syphon is not less than 70 lbs. per square inch. 



The Arabs at a later period not only knew of this law, but also understood 

 the operation of what we engineers call the " hydraulic mean gradient." The 

 aqueducts constructed by them for supplying Constantinople with water have been 

 very fully described in those most interesting ' Letters from Turkey,' written by 

 Field-Marshal von Moltke in the years 1835 to 1839. He says that the Arabs 

 knew that water under pressure reaches its own level (rich gleich stellt), for they 

 conveyed the water across the valleys in leaden pipes. They had found by expe- 

 rience that the friction through the aqueduct was lessened if openings were made 

 in the course of the line of pipes ; and along hill-sides and in places where the 

 pipes were not in deep cuttings, funnel-shaped shafts or wells were made, which 

 acted as air-holes. But in crossing deep valleys, where, of course, no such holes 

 could be made, they built stone pyramids, called " Suterasi," or water-balances, on 

 the top of which they placed small basins, into and out of which the water was 

 conducted by a leaden pipe laid up one side of the pyramid and down the other. 

 The level of these basins was so arranged that they were at an inclination rather 



