For this purpose, however, it was necessary that the pump-work employed at first only for raising water should undergo some alteration. To use it for extinguishing fires, it was requisite that the water should be speedily driven from the upper aperture as high as possible; whereas for the first purpose, it is enough if the water be thrown out in sufficient quantity to be conveyed to the place of its destination. More additional parts necessary for extinguishing fires would then be an imperfection; as the power which gives the water a needless velocity might be employed with more advantage to raise a greater quantity of it. In my opinion it is highly probable that Ctesibius had an idea of converting his pump into a fire-engine, for his scholar, Hero of Alexandria, speaks expressly of this use, and describes the construction of a forcing-pump with two cylinders[583]; but it is very doubtful whether this application of it soon became general, and whether this advantageous machine was known to the ancient Romans. What I have been able to learn on the subject is as follows. Pliny the younger, after telling the emperor Trajan, in one of his letters, that the town of Nicomedia in Bithynia had been almost entirely destroyed by a fire, adds, that the devastation had been increased by a violent storm which took place at the time; by the laziness of the inhabitants, and by the want of machines or apparatus proper for extinguishing the flames[584]. The word _sipho_, which the author here uses, was certainly the fire-engine of Ctesibius; though some under this term understand only aqueducts, canals, and pipes for distributing water throughout the city. I will not deny that this word may have signified such pipes, particularly on account of a passage in Strabo[585], where he speaks of the subterranean conduits of Rome, and says that almost all the houses had cisterns, _siphones_, or water-pipes, and running streams. But Pliny at the same time mentions water-buckets, which may be considered as an appendage absolutely necessary to a fire-engine. It is also hardly possible to believe that a town, immediately situated on an arm of the sea, should be destitute of water[586].