Journey to lake, must have been indeed immense, and collected
fop. with vast labour and expence. These collections of earth
weif'fupported on each side fcy walls of stone; and to
prevent the column of water in the canal from becoming,
teoheavyfor the embankment to support it, sluices are
cut at certain distances, by which ihe superfluous water
passes off, either immediately in to the lake, o r upon the
low lands, and sometimes into ditches made into the
middle of the embankment, to serve as reservoirs . This
last contrivance seemed to imply some practical knowledge,
at least, of hydrostatics. Fosf the water in thafe
ditches was generally kept at a meanjheight between the
two surfaces of the canal and of the lake ; or of the for?
mer and the low ground next to i t ; by which means
the pressure against the'two banks is divided, -requiring
less resisting power in either. The column of water in
the reservoir counteracts a column of equal heighfcin the
canal, and the depth of water in the lake destroying all
the pressure of that- in the reservoir not above;t?he surface
of the lake. The circumstance also of leaving a
ditch in the embankment, diminished the quantity of
earth to be collected from afar; for it appears in the
Jesuits’ maps of the country, through which th e , canal
passes, that a vast proportion of it had consisted of lakes
and morasses, several parts of which appear to have been
since reclaimed, and are now, as well as the upper surface
of the embankment, regularly cultivated .
4«#evBÈal;4 nfeidré%âeres.' bf 4béi>ground, Wbich«still is
s-wampy^'dhdastirroUfl'ds^bfeke^are'CoVere^rwith the fo°;,—
lien-wha^ or nymphéa nehasnfeo of '-Linnaeus, already
mentioned- in this volume.. ' ; TheÆHmese have always
heldv M s plant in sdch'high^alne,' that -at •lengtrh they
regarded it {^isatredv^Thauslfaradte#,»however, has not
Limited it-tb' merely ornamental <and aa-seless J^pur poses ;
for’- it^te^terbdn'e'ednamong • the>g'articles' nff! <the > tahlet
T h è h ponds arè^geneml’l}èêover©d* Wifrhdt; and’ exhibit
a1 very he&uiiful ap pearafie*eî wh en in flower'd* The "seeds
are'[sUnie what o f ihs^ssae anff form-of an-acorn; and; of
1 a^tastbi-nfoic delicate] than' that of almonds.!efTheyivare
fjx&d byUhe lower?<iex(®êMiitÿ in to n e flat surfaaefofm
substance-formed into 'th e -shape - off broàé inverted
eohW. iThedrof^ We s-lice'd;! and in the*rsummer served
w i t h ^ . 'i They are also laithttp in salt and vinegar far
' iTrom ’this, root, the -Egyptians!are; supposed to havç
prepared their Cblbcasia' but the plant is net w-nb: longer
found in that^ouhtfly: from whichOTCumstance some
naturalists infer',, that!*itMbVer Was- indigenous therejtbsut
cultivated . b y thfe inhabitants *with extreme1 bare. The
ancient Romans made repeated;efforts!to ràiscuk amongst
themv from Seeds brought ©uf-bf Egypt -; dn d&e modern
attempts to cultivate?it in Europe, th@|with‘the assistance
bffartificïaidihàt; 'seldomdiaKte àüeoëfesBWî< ImChama
it - often grows spontaneously-, rbuitivstted in the