considers the Fiumicino arm to have been originally an artificial canal dug by Trajan to connect his port with the Tiber, and calls it Fossa Trajana. As the delta advanced the canal extended itself beyond the limits of the port of Trajan, from which its mouth is now distant a mile and a half. It was deepened by Fontana at the desire of the reigning Pope, and is now the only navigable branch. By means of stakes the channel is narrowed, and the requisite depth of water and velocity of current maintained; but the width is so contracted by this means, that two small vessels can scarcely pass each other. Similar small steamers formerly ascended the river as high as Ponte Felice, about fifty-one and a half English miles above Rome, while large barges went as far as Orte, two miles above the confluence of the Nera, and distant seventy-one miles from the city by the windings of the stream ; but now, owing to the state of the river, the steamers ascend only to Scorano near Correse, and the barges to Ponte Felice. The barges are towed by the steamers as far as the latter go, and the remainder of the distance by buffaloes. The steamers draw from three feet three inches to three feet eight inches of water, and have a speed of from eight to ten miles an hour, but owing to the rapidity of the current their progress is extremely slow, and they are now employed exclusively as tugs; few persons caring to encounter the weariness and discomfort of the voyage.

Above Orte the Tiber is navigated only by rafts, which descend the river during the autumn and winter months, and on their arrival at Rome are broken up and sold. The navigation of the upper Tiber presents peculiar difficulties, owing to the great fall of the river and the number of rapids in its course. The subject has engaged the attention of successive Pontiffs, among others of Clement XII., who appointed the engineers, Andrea Chiesa and Bernardo Gambarini, to survey the course of the Tiber, and report upon the feasibility of rendering it navigable from Ponte Nuovo, just below the mouth of the Chiascia to the Nera, a distance of fifty-two English miles and a quarter.

The Tiber is described by them as flowing below Ponte Nuovo in a wide and shallow bed, occasionally encircling islands of small extent. In the neighbourhood of Todi the rapids commence. The river rushes with great force through the narrow gorge of Il Forello, and soon after precipitates itself into the gulf or chaldron known by the name of Inferno, where there is a tradition that a raft was once swallowed up and never reappeared. Emerging thence it descends by a series of rapids known by the names of Infernello, Cacastozza, Molinacci and etc., to its junction with the Chiana. The whole fall of the river is no less than two hundred and sixtysix feet and a half in the course of fifty-two miles and a quarter. The river also is liable to change its course, which increases the difficulty of dealing with it.

The attempt to overcome the difficulties created by the shallowness of the river in one place, and its rapidity in another, would involve, the engineers consider, an enormous expenditure, with the almost certainty of failure. The piling and embankments required to narrow the current of the river and increase its depth would be wholly or partially swept away during great floods, while the locks and dams, which must be constructed at the rapids, would not only be very expensive in the first instance, but liable to be destroyed by the force of the swollen current beating against their walls. They might also be rendered useless by a change in the bed of the river. They suggest, therefore, that, instead of trying to render the river itself navigable, a canal should be formed parallel to its course, and supplied with water from it; the river, where circumstances admit, being used as part of the canal. The report was submitted submitted in the year 1746 to Benedict XII. but was never acted upon; either because the Popes were too poor to bear the expense, or because such a canal, not connecting any large towns, would not be likely to pay. The scheme may, however, be revived and carried out under the new government when the Campagna is cultivated and the canal can be turned to better

account.

The estimates of the length of the Tiber differ to the extent of twenty miles. I have adopted that which I consider the most correct; according to which the total length of the river from its source to the sea is two hundred and fifty Roman, or two hundred and thirty-two English miles, and the distance from Rome to Fiumicino twenty-two and a half.

The distance in a direct line from the source of the Tiber on the north to that of the Salto on the south is one hundred and forty miles; and from the source of the Paglia on the west to that of the Nera on the east about seventy-eight.

If

we take the mean of the greatest and least widths, the basin of the Tiber, or area drained by its tributaries, may be estimated roughly at six thousand five hundred square miles.* This includes, of course, the minor basins of the Chiascia, the Chiana, the Nera and the Anio.

The colour of the river is owing to the constant falling in and abrasion of the banks in the alluvial valley through which the river flows after quitting the mountains. The fine soil is quickly diffused through the water, and imparts to it its peculiar tinge.

The mud of the Tiber is said not to possess the fertilizing property of the slime of other rivers, which, by enriching the land which they overflow, make some amends for the damage caused by their inundations. But this absence of

fertilizing power is only temporary and apparent. The infant river in its rapid descent as a mountain torrent carries with it rocks, gravel, and sand, and when it overflows its banks, covers the fields with a debris which seems to condemn them to perpetual sterility. As the declivity of its channel diminishes, the stones and gravel are left behind and the sand alone is deposited. But it is not until it arrives in the plains and flows with a sluggish current that the finer particles of earth, and any organic matter it may contain, subside to the

*The basin of the Tiber is extremely irregular, and more accurate measurements have shown that it exceeds seven thousand square miles.

† If water flows three inches in a second, it will carry clay; if six inches, sand; and if twelve inches, gravel.

bottom during floods, and constitute the rich loam which imparts exuberant fertility to the lower courses and deltas of rivers. The Tiber, as low down as Rome, retains many of the characteristics of a mountain torrent. Even when the river is low, the current is strong; and during floods the commotion of the waters allows nothing to be deposited but the heavier sand, while the fine earth and lighter organic matters are held in suspension and carried onward to the sea. The deposit of the Tiber-for mud it can scarcely be calledconsists almost entirely of volcanic sand or minute particles of volcanic minerals derived from the disintegration of the tufa, among which mica is conspicuous, sparkling like diamonds in the sun. It contains no appreciable quantity of organic matter, is wholly free from smell, and in situations where it can dry readily, is not likely to evolve unwholesome gases, or to produce the deleterious effects attributed to it.

If we examine it under a high power of the microscope, we detect, besides the mica, the dark coloured pyroxene or augite, and fragments of amphigene or leucite, sometimes called white garnet, which is found in great abundance in the neighbourhood of Rome, and often used in cheap jewelry. This volcanic sand is very different from pure silicious sand, consisting, as it does, of compound minerals, which, when exposed to the atmosphere, undergo a slow decomposition, are resolved into the earths which constitute the soil best adapted to the growth of plants. Volcanic soils are proverbially fertile, and, though the impalpable earths already liberated by the chemical decomposition of these volcanic minerals are carried away, as I have said, by the current of the Tiber, the coarse sand will in its turn undergo decomposition in situ, and the Prati and other lands overflowed by the Tiber be eventually benefited by the top dressing they receive.

WATER OF THE TIBER.

If we look upon the seething waters of the Tiber in a flood, yellow as pea-soup, and apparently of the same consistence, we may be disposed to pity the Romans of the early republic, who for four hundred and forty years had little else to drink. Equally hard may seem the lot of their descendants of the middle ages, who were constrained to return to the water of their turbid stream.* The aqueducts, which once conveyed whole rivers to what was then the capital of the world, had long since been broken drown by the Barbarians or fallen into decay. Rome, reduced to the dimensions of a petty state, and drained of its resources by civil wars and continually recurring calamities, was unable to keep such gigantic structures in repair. The Piscina, or reservoirs, in which the water deposited its mud, were no longer cleaned out; the conduits were obstructed by calcareous incrustations, and the springs from the distant mountains ceased to flow in their accustomed channels or were wasted by leakage before they reached the town. The water of the Tiber, supplemented by a few small springs and wells, was thus the only resource of the Romans, and was sold through the city in barrels, after it had been allowed to settle for six months, and deposit the impurities it contained.t This state of things continued up to the time of Pope Pius IV., 1559, who repaired the Aqua Virgo, now called the Acqua Vergine, the aqueduct whose restoration entailed the least expense; and about twenty years later

* When Rome was invested by the armies of Alaric, the aqueducts were broken down, and the citizens were driven to drink the long-disused water of the muddy Tiber. But this was one of the privations incident to all sieges, and trifling compared to others which they had to endure.

†The mother of Rienzi eked out her gains as a washerwoman by hawking this water through the streets.