it can be adorned with figures, which, however, must be suitable for the pressure.

(e) In a fountain where air, already contained in a vessel, is compressed by injected water; afterwards, however, the compressed air expels the water itself, upon which it violently presses.

The fourth principle is rarefaction (a) by fire applied to fountains (b).

(a) Either of the air extruding the water, or of the water turning into vapors, which subsequently expel the water.

(b) We present one such device, which has two vessels made of brass, separated by a tube coiled into spirals. Through an underlying fire, heated air will ascend from the lower vessel through the tube into the upper vessel and will project distilled water or spirits of wine into the outside air. If you apply fire to the leaping spirits of wine, it will catch a flame and exhibit pleasant phenomena.

He who knows how to apply and combine these principles well will easily be able to adorn any hydraulic machines himself and resolve those elaborated by others into their principles.