THE apprehensions you express, Sir, that the lake will be in danger of being entirely drained if a communication should be opened between that and the sea, by means of the river, are agreeable to that prudence and forethought you so eminently possess; but I think I have found a method to obviate that inconvenience. A channel may be cut from the lake up to the river so as not quite to join them, leaving just a narrow strip of land between, preserving the lake; by this means it will not only be kept quite separate from the river, but all the same purposes will be answered as if they were united: for it will be extremely easy to convey over that little intervening ridge whatever goods shall be brought down by the canal. This is a scheme which may be pursued, if it should be found necessary; but I hope there will be no occasion to have recourse to it. For, in the first place, the lake itself is pretty deep; and in the next, by damming up the river which runs from it on the opposite side and turning its course as we shall find expedient, the same quantity of water may be retained. Besides, there are several brooks near the place where it is proposed the channel shall be cut which, if skilfully collected, will supply the lake with water in proportion to what it shall discharge. But if you should rather approve of the channel's being extended farther and cut narrower, and so conveyed directly into the sea, without running into the river, the reflux of the tide will return whatever it receives from the lake. After all, if the nature of the place should not admit of any of these schemes, the course of the water may be checked by sluices. These, however, and many other particulars, will be more skilfully examined into by the engineer, whom, indeed, Sir, you ought to send, according to your promise, for it is an enterprise well worthy of your attention and magnificence. In the meanwhile, I have written to the illustrious Calpurnius Macer, in pursuance of your orders, to send me the most skilful engineer to be had.