‹‹‹ Vitr. 9.8.5 | Table of Contents | Vitr. 9.8.7 ›››
6On these also, either on columns or pillars, the hours are marked, to which a figure, holding a wand and rising from the lower part, points throughout the day, the increase and decrease whereof is daily and monthly adjusted, by adding or taking away certain wedges. To regulate the flow of the water, stoppers are thus formed. Two cones are prepared, one convex, the other concave, and rounded so as to fit exactly into each other. A rod, by elongating these, or bringing them together, increases or diminishes the flow of water into the vessel. In this manner, and according to the principles of this machine, water-dials for winter are constructed.
6The hours are marked in these clocks on a column or a pilaster, and a figure emerging from the bottom points to them with a rod throughout the whole day. Their decrease or increase in length with the different days and months, must be adjusted by inserting or withdrawing wedges. The shutoffs for regulating the water are constructed as follows. Two cones are made, one solid and the other hollow, turned on a lathe so that one will go into the other and fit it perfectly. A rod is used to loosen or to bring them together, thus causing the water to flow rapidly or slowly into the vessels. According to these rules, and by this mechanism, water clocks may be constructed for use in winter.