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109.

of right angles: for ye water in its motion striking against that part of ye pipe wch is opposite to it, put it in danger of breaking and is considerably retarded by that encounter. 

  If we would that ye spouts should preserve their force for several years, we must make ye conduits a little larger than they were made according to ye calculation for there is heaped upon them dirt and filth wch hinder a little ye running, and also there are some water wch carry with them petrific atoms, wch joyning together form stones wch stop up ye conduit I have observed in ye Aquaduct at Azcusil, and in ye observatory where ye waters are separated, a bason wch hath a cross spout in ye middle of half a foot heigh, ye circumference of this bason is of copper where there is made many circular holes of an inch diameter to know ye quantity of water wch is in ye aquaduct, but by little and little there is heaped in these holes a stony matter wch at last entirely stops them up ye waters not being able to pass wch is very surprising: for it seems that ye running water ought to carry away ye filth wch might be there heaped up.  This done after ye same manner as ye snow is heaped up at ye side or upon ye branches of bushes when there is [[mists?]] in a great frost[?]; for ye wind carrying ye small particles or atoms of ye icy vapours introduced that wch follow, and at last there is made a mass of 2 or 3 inches height in ye like matter of water carrying along with it ye small stony atoms where with it is changed in passing thro ye earth, some of them stick in ye pores of ye metals and others wch follow are joined to ye first according to their disposition and figure.  There passeth many wch do not stick but in many years there is at last heaped up enough entirely to stop the holes as if it were a sufficiently hard stone, so that about every 50 years ye pipes might be taken away and new ones made.

  When ye conduit of ye water in ye pipe shall be divided into many small conduits to make many spouts, we must consider all ye inches of water wch all ye spouts together ought to give to determine ye largeness of ye great pipe of ye conduit and afterwards be reduced by calculation to one hole of ye spout.

     Example

  The principal conduit is divided into 6 pipes of wch 2 have 3 lines passage, 2 others 5, the 5th 6, and ye 6th 8, ye height of ye reservatory is supposed to be 52 foot; therefore if ye conduits are sufficiently large, and there is water enough in ye reservatory ye passages of 3 lines will give each 4 inches according to ye rules and ye table above those 5 lines will give each 11 1/2 inches that of 6, 16 inches, and that of 8, 28 inches, ye sum of ye expanse of ye water of all ye spouts shall be 74 2/9 inches, there for according to ye rule given 

    as 4 inches is to 74 2/9 inches
    so is 9 ye square of 3 to 168

  whose square root is 13 near, ye first conduit must therefore be 13 inches large, each of ye conduits wch have at ye end 13 lines passage will 3 inches large, each of those that have 8 lines passage will have 5 inches and for a passage of 6 lines ye conduit shall have 6 inches and for that of 8 lines, it will have 8 inches.  then all those conduits will give their spouts as heigh as they ought and if ye water wch  furnisheth ye reservatory be 74 inches, these spouts will go continually ye spout of 8 lines will go ye heighest of all, and to know its height we shall first in ye table that a spout of 8 foot ought to have its reservatory of 58 foot four inches height and that of 45 foot out to have 51 foot 7 inches; wherefore ye spout is between 45 and 50 foot, and very near 45 foot, and if we calculate for ye height of a spout at 40 foot, we shall find ye 2 foot 1/2 inch for ye height of that reservatory; when we many conclude that ye spout shall be little less than 46 foot: