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together, increases or diminishes the flow of water intothe vessel. In this manner, and according to the prin-ciples of this machine, water-dials for winter are con-structed. If the addition or removal of the wedgesshould not be attended by a correspondent increase ordecrease in the days, for the wedges are frequently im-perfect, it is to be thus remedied. Let the hours fromthe analemma be placed on the column transversely, andlet the lines of the months be also marked thereon.The column is to turn round, so that, in its continualrevolution, the wand of the figure, as it rises, points tothe hours, and, according to the respective months,makes the hours long or short. Other kinds of winter-dials are made, which are called Anaporica. They areconstructed as follows. With the aid of the analemmathe hours are marked by brazen rods on their face,beginning from the centre, whereon circles are drawn,showing the limits of the months. Behind these rods awheel is placed, on which are measured and painted theheavens and the zodiac with the figures of the twelvecelestial signs, by drawing lines from the centre, whichmark the greater and smaller spaces of each sign. Onthe back part of the middle of the wheel is fixed a re-volving axis, round which a pliable brass chain is coiled,at one of whose ends a phellos or tympanum hangs,which is raised by the water, and at the other end acounterpoise of sand equal to the weight of the phellos.Thus as the phellos ascends by the action of the water,the counterpoise of sand descends and turns the axis, asdoes that the wheel, whose rotation causes at times thegreater part of the circle of the zodiac to be in motion,and at other times the smaller; thus adjusting the hoursto the seasons. Moreover in the sign of each month areas many holes as there are days in it, and the indexwhich in dials is generally a representation of the sun,shows the spaces of the hours; and whilst passing fromone hole to another, it completes the period of the

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