I 9 2 BOOK VI. 



sometimes on working days, and are thus not always near the pump, and as 

 the pump, if necessary, must continue to draw water all the time, a bell rings 

 aloud continuously, indicating that this pump, or any other kind, is uninjured 

 and nothing is preventing its turning. The bell is hung by a cord from 

 a small wooden axle held in the timbers which stand over the shaft, and 

 a second long cord whose upper end is fastened to the small axle is lowered 

 into the shaft ; to the lower end of this cord is fastened a piece of wood ; 

 and as often as a cam on the main axle strikes it, so often does the bell ring 

 and give forth a sound. 



The third pump of this kind is employed by miners when no river capable 

 of turning a water-wheel can be diverted, and it is made as follows. They 

 first dig a chamber and erect strong timbers and planks to prevent the sides 

 from falling in, which would overwhelm the pump and kill the men. The 

 roof of the chamber is protected with contiguous timbers, so arranged that 

 the horses which pull the machine can travel over it. Next they again set up 

 sixteen beams forty feet long and one foot wide and thick, joined by clamps 

 at the top and spreading apart at the bottom, and they fit the lower end 

 of each beam into a separate sill laid flat on the ground, and join these by a 

 post ; thus there is created a circular area of which the diameter is fifty 

 feet. Through an opening in the centre of this area there descends an 

 upright square axle, forty-five feet long and a foot and a half wide and thick ; 

 its lower pivot revolves in a socket in a block laid flat on the ground in the 

 chamber, and the upper pivot revolves in a bearing in a beam which is mor- 

 tised into two beams at the summit beneath the clamps ; the lower pivot is 

 seventeen feet distant from either side of the chamber, i.e., from its front and 

 rear. At the height of a foot above its Iqwer end, the axle has a toothed wheel, 

 the diameter of which is twenty- two feet. This wheel is composed of four 

 spokes and eight rim pieces ; the spokes are fifteen feet long and three- 

 quarters of a foot wide and thick 17 ; one end of them is mortised in the axle, 

 the other in the two rims where they are joined together. These rims are three- 

 quarters of a foot thick and one foot wide, and from them there rise and 

 project upright teeth three-quarters of a foot high, half a foot wide, and six 

 digits thick. These teeth turn a second horizontal axle by means of a drum 

 composed of twelve rundles, each three feet long and six digits wide and 

 thick. This drum, being turned, causes the axle to revolve, and around this 

 axle there is a drum having iron clamps with four-fold curves in which catch 

 the links of a chain, which draws water through pipes by means of balls. 

 The iron journals of this horizontal axle revolve on pillows which are set in 

 the centre of timbers. Above the roof of the chamber there are mortised 

 into the upright axle the ends of two beams which rise obliquely ; the upper 

 ends of these beams support double cross-beams, likewise mortised to the 

 axle. In the outer end of each cross-beam there is mortised a small wooden 

 piece which appears to hang down ; in this wooden piece there is similarly 



"The dimensions given in this description for the various members do not tally. 



I 



