Autobiography of Sir John Rennie, F.R.S. 7

Autobiography of Sir John Rennie, F.R.S. 7

Having passed Sion, we left Brieg early on the 10th of August, and as

soon as we began the ascent I descended from the carriage, and with line

and rule I measured every bridge until we reached Boveno, on the Lake

Maggiore. I sent off from Milan, as I had promised, a detailed account of

this celebrated road to my father, giving a drawing and account of every

work, which I afterwards had the gratification of knowing afforded him

great pleasure. The whole Pass must have at first sight been appalling to

the engineers who traced the line of road; and although many other works

of the kind of greater magnitude have been since executed, nevertheless,

all things considered, it is worthy the approbation of mankind, and does

great credit both to those who designed and those who executed it.

 

We reached Milan[1] on the 12th of August, and I was much struck with the

fine canal which unites it with Pavia, and which can only be compared

with the canals of Belgium. It has been said that the first pound lock

was invented and executed by the famous Leonardi da Vinci, but subsequent

inquiries have induced me to believe that our own country is entitled to

the honour in the Exeter ship canal. I was also greatly pleased with the

system of irrigation employed generally throughout Lombardy. This system

was originally introduced by the Italians themselves, and during the

Austrian rule was carried to the greatest perfection, Lombardy being by

nature peculiarly well adapted to it. The vast and fertile valley of the

Po is for the most part destitute of rain during the summer, when it is

most wanted; but it fortunately happens that at this season water is most

abundant from the melting of the snows on the Alps, which descend into

the adjacent lakes and rivers, and would be otherwise wasted and thrown

away if not employed for fertilizing the land. The water, therefore, at

this season is conducted by an elaborate system of artificial canals,

and distributed over the adjacent lands according to their respective

levels, at a certain price, varying with the quantity distributed. Thus

the constant supply of water, the high temperature, and the fertility of

the soil combined, produce the most abundant crops, and the plains of

Lombardy are rendered the most productive and valuable in Europe; whereas

in winter, when the temperature is lowest, the snow is congealed on the

Alps, and comparatively little water comes down when it is least wanted.

 

From Milan we reached Verona, where the bridge, consisting principally of

brick, with binding courses of marble, can boast of one of the largest

brick arches in the world, an excellent example of what may be done with

this material when properly handled. After passing Vicenza and Padua, we

reached Venice early in September, 1819.

 

The extraordinary and at the same time most beautiful and novel

appearance of the city, with numerous towers and spires, about which I

had read and heard so much, and had so long wished to see, now stood

before me, and its loveliness more than realized my most sanguine

expectations. When I considered its origin, a few fishermen’s huts built

upon the mud banks of the lagoon by men flying from the invasion of

Attila, then the rise of the great republic whose wealth, conquests,

and influence were destined hereafter to play such an important part in

the world, and lastly the fallen and degraded state in which it then

presented itself before me, I was lost in astonishment; I was for a while

transported as it were in a dream, and could scarcely believe where I was.

 

The Grand Canal first attracted our notice,--perhaps there is no

thoroughfare in the world lined with so many magnificent palaces,--and

along which we passed until we came to the Rialto, a drawing of which I

made and sent to my father. But if I was delighted, and I may almost say

astonished, at the Grand Canal, I was still more so with the Place of St.

Marc and its surrounding buildings, so varied in their architectural

styles, yet each so picturesque and elegant in itself, and combined

together forming at once the most interesting and beautiful scene of

the kind in the world. It is one of those sights, at least speaking for

myself, that never satiates--the more I looked the more I admired it. As

to the details of these different buildings which we saw, they are so

much better described in the numerous guide books that it is unnecessary

to repeat them here.

 

I visited every part of the lagoons, including the various islands, all

of which are more or less deserving of notice, particularly the island

of Murano, the seat of the celebrated glass manufactories; and also the

Moravian establishment. But what really most interested me were the

lagoons, and the means which must have been resorted to for keeping them

open, notwithstanding the numerous causes which were and are constantly

in operation to fill them up with the alluvial matter brought down

from the mountains and plains by the various rivers and streams which

discharge their waters into this portion of the Adriatic, also from the

alluvium brought in from the adjacent shores, by the tide, which rises

from 2 to 4 feet, and at times, during heavy gales from the southward, as

much as 6 feet, overflowing the quays of St. Marc’s Place.

 

There was a long-continued discussion amongst the numerous distinguished

mathematicians, engineers, and others who have written upon this subject,

as to the best way of preventing the filling up of the harbour. Some

contended that the only method of effecting this was to admit all the

rivers into the lagoons freely; for although they might deposit a certain

amount of alluvial matter, nevertheless the great quantity of water

discharged would alone be sufficient to carry away this deposit. But they

forgot that when the rivers met the sea the current would necessarily

be checked and rendered powerless to carry forward any matter which

might be held in suspension, and that consequently the detritus would be

deposited and form banks and shoals which the waters could not remove;

thus in time the lagoons would be filled up, grass marshes would be

formed, the city of Venice would be united to the mainland, and the

harbour would be destroyed. On the other hand, it was argued, for the

reasons above mentioned, that the only way to preserve the lagoons and

the port of Venice was to exclude the rivers when densely charged with

alluvial matter, and only to admit their waters at certain times, when

they were comparatively clear; thus all the advantage would be obtained

from the scour of these rivers, without the disadvantage arising from

their deposits. Ultimately the arguments of the latter prevailed, the

rivers were excluded from the lagoons by making a capacious canal all

around them with sluices at their mouths, by means of which the waters

were discharged into the lagoons when they were tolerably clear of

alluvial matter; the surplus waters were discharged into the adjacent sea

clear of the lagoons, and any alluvial matter which was brought in from

the sea was removed by dredging from the main channels of the lagoons, so

that they were in a fit state to admit the tidal waters and thus to keep

the lagoons open.

 

But there was another important agent to be provided against, namely,

the alluvial matter brought in by the winds, waves, and currents from

the scouring of the adjacent shores of the Adriatic; this is done to a

certain extent by dredging. Originally these banks contributed materially

to the formation of the outer banks, which protect the lagoon on the

sea side. If these banks were broken through or completely swept away,

which the storms of the Adriatic frequently threatened to do, the lagoon,

and with it the port, would be seriously injured or totally destroyed.

This was remedied by defending this outer barrier bank of the lagoon by

facing it with stone, and where the sea was most violent by constructing

a solid breakwater of stone, and protecting it further by stone filters

carried out a sufficient distance into the sea in order to divert the

current, and to enable the alluvial matter to be deposited between them

so as to form an additional protection to the main breakwater; this was

accordingly done, and thus an extraordinary work at great expense has

been constructed between Lido and Malamocco, the principal entrances from

the sea to the lagoon, for a length of four miles, where the effects of

the sea are greatest.

 

Malamocco is the principal entrance for large vessels, and the channel

from thence to Venice has been deepened, chiefly by dredging, to the

extent of 24 feet at low water. Lido, which is the next chief entrance

and the nearest to Venice, being about 1½ mile distant from it, serves

for the general class of merchant vessels. The other entrances of Foggia,

Tre Porte, and the Piave, are seldom used except for fishing vessels,

and it is not necessary to do more to these than to keep them in their

present state, that is, to prevent deterioration, as it is an object

of importance to allow the great mass of water by which the lagoon is

chiefly preserved to pass in and out of the main entrances, Malamocco and

Lido. Upon the whole it appears to me that this latter plan is the wisest

that could be adopted, and the result has proved that it has been so far

successful, although attended with considerable expense. It is in fact

a choice of two evils, and the least has been chosen. It is, I believe,

admitted that the port of Venice is now capable of receiving as large,

if not larger, vessels than she ever received before; for it should be

recollected that in the most flourishing times of Venice there were no

ships drawing 23 or 24 feet, and vessels of this size can now enter and

depart at all times. Hence Venice has been converted into a port fit

for modern requirements; but it must always be borne in mind that so

strong are the natural obstacles against its maintenance that nothing can

preserve it in its present condition but the most constant vigilance and

care. Fortunately the method of dredging by steam has been introduced,

and this may be done to any extent, at a comparatively moderate cost,

but it can only be compensated for when there is a sufficient amount of

trade to pay for it. Still, in whatever way we may consider the question,

it must be admitted that the port of Venice has been preserved in a

most extraordinary manner during so many centuries, notwithstanding the

natural obstacles against it; and now that it has been connected with the

kingdom of Italy, there is no further drawback to its full development,

and it only requires self-reliance and energy to render it what it once

was, one, if not the most important, of the commercial cities of Italy.

 

At Bologna we had the pleasure of making the acquaintance of the

celebrated linguist Mezzofanti, whose modest and simple manner,

accompanied by his extraordinary acquirements, quite enchanted us. The

singular fact is that at the time of our meeting him he had never been

out of the province of Bologna, and yet he had acquired the knowledge of

twenty-four languages, and, as far as our limited acquaintance went, he

spoke the English, German, French, Greek and Latin tongues perfectly; and

those conversant with the Oriental languages informed us that he spoke

them equally well. He appeared to be completely absorbed in languages,

and was scarcely acquainted with any other branches of knowledge; still

his wonderful mastery of this branch of study was a great acquirement,

and must have required vast powers of memory as well as indefatigable

study.

 

From thence we passed through Ravenna to Ancona, the position of which is

good, occupying as it does a salient point of the coast. The water is

deep and there is a commanding height for a citadel. The Roman emperors

resolved to take advantage of the situation, and built a town here, the

place being well adapted for a seaport. They accordingly made a mole

on the south side to protect the harbour against the most dangerous