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103.

in ye parabola CNR than in ye parabola CPR.  Here are ye experiments wch I have made with water wch ought to be more retarded by ye air than a ball of iron or a bomb.

In ye figure preceding let us suppose A B C a pipe of 6 foot heigh from ye surface of ye water at ye top of D in ye reservatory to ye passage C;  ye direction of ye sput was 45 degrees and by what we have said C G wch was ye amplitude of ye parabola ought to be 10 feet:  But ye spout was scattered towards ye end, and that will approach nearst 10 foot was 9 foot 10 inches, and by consequence that sput wanted but 1/64 that is to say 2 upon 120.  But having made experiments upon greater heights, ye spout diminished more of it amplitude to proportion for ye greater resistance of ye air, and that diminution ought to be made in proportion to ye heights of ye spouts, and so we must take ye double of the perpendicular height of ye spouts to know their amplitude of ye parabolick spout at ye elevation of 45 degrees

[[image:  diagram of reverse J shaped tube with liquid streaming from the end annotated C B E D F]]

  The spouts of quicksilver produce ye same but their extremity is scattered more than ye spouts of water, whereof ye cause is that ye superior mercury B F slides upon ye inferior C E D by its incounter and on ye contrary ye mercury towards E descends by its weight and by ye shoc of that wch is above it;  wch make ye drops of ye quicksilver become seperate one from ye other between D and F from above downwards;  but they do not scatter in largeness.  And if we put our eyes in ye plane of ye direction of ye spout it will appear but as a stream of ye same largeness throughout, wch it hath as its going out of ye passage because ye drops not scattering at ye going out, ye nearest ye eye cover all ye other wch are below in ye whole extent of ye spout.

  To move by experience that ye heavier ye matter ye greater ye parabola, I hung a ball of steel to a thread of 3 1/2 foot long and having elevated it to an arc of 50 degrees I let it go, it returned after having mounted on ye other side to 49 degrees 45 minutes;  ye arc of 15 minutes, wch remained, was 6 lines large and by consequence it lost but a line and 1/2 or near in falling to ye point of repose.  I put afterwards a boul of wax of ye same grossness charged with a small weight, so that its specific gravity was as that of water; and having elevated it to 50 degrees it returned to 4 inches at the second beating it lost therefore 8 times as much by ye resistance of the air as that of ye steell, wch is near in proportion of ye specific gravity of water to steel.

When in a pipe ye holes are one above another and the spouts are horizontal, we may know ye length of ye spouts upon an horizontal plane by ye same rules in this manner.