All these circumstances have been related by the inventor in a particular work; which, on account of the excellent engravings it contains, is exceedingly valuable[610]. Of these, the first seven represent dangerous conflagrations at which the old engines were used, but produced very little effect. One of them is the fire which took place in the stadthouse of Amsterdam in the year 1652. The twelve following plates represent fires which were extinguished by means of the new engines, and exhibit, at the same time, the various ways in which the engines may be employed with advantage. According to an annexed calculation, the city of Amsterdam lost by ten fires, when the old apparatus was in use, 1,024,130 florins; but in the following five years, after the introduction of the new engines, the loss occasioned by forty fires amounted only to 18,355 florins; so that the yearly saving was ninety-eight per cent. Of the internal construction of these engines no description or plates have been given; nor do I remember to have read a passage in any author from which it can be concluded that they were furnished with an air-chamber, though in the patents they were always called _spouting-engines_, which threw up one continued jet of water. The account given even of the nature of the pipe or hose is short and defective, probably with a view to render it more difficult to be imitated. It is only said that it was made of leather in a particular manner; and that, besides being thick, it was capable of resisting the force of the water. The conveyer or bringer was invented also about the same time by these two Dutchmen. This name is given at present to a box which has on the one side a sucking-pump, and on the other a forcing-pump. The former serves to raise the water from a stream, well, or other reservoir, by means of a stiff leathern pipe, having at the extremity a metal strainer pierced with holes to prevent the admission of dirt, and which is kept suspended above the mud by a round piece of cork. The forcing-pump drives the water thus drawn up through a leathern pipe into the engine, and renders the laborious conveyance of water by buckets unnecessary.