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and distribution of the waters of the Amstel and Noordzee Canal through the various
channels. In spite of the heavy rains at the time of our visit, the difficulty of
full efficiency in this peculiar water carriage sewage system was well illustrated
every time the launch went astern in order to round a corner.
The new portion of Amsterdam, extending in a semi-circle round Old Amsterdam,
is drained directly into the Zuider Zee. A further portion of the town which
will eventually ring the mid- or new-town is largely on polder land, below the level
of the remainder of the town. The biological systems, such as the activated sludge,
will eventually be used here.
It will be readily inferred that the water of the Ij is not of the purest description
but a complication of the pollution is afforded by the extensive use of paraffin
motors amongst the barges, both on canals and harbour, together with the special
and vast oil dock about the basin of which we sailed. A peculiar condition of the
water is that for about one metre in depth there is a fine emulsion of oil, very evident
at the bathing station on the harbour front.
The problem of maintaining a quarantine station which is, of necessity, from
time to time empty, against the destructive efforts of boys (especially, Dr. Veldhuizen
mentions, the smashing of windows) is illustrated by the use of this station
as a Venereal Ablution and Immigrant Disinfection centre. Diphtheria carriers
are also lodged here.
Dr. Veldhuizen was unable to show us the actual process of disinfestation
by means of " Cyclon." It is interesting that a ship under disinfestation at the time
of our visit was using the time honoured sulphur dioxide method. He explained the
principle which is that of using hydrocyanic acid with an admixture of a tear gas.
The hydrocyanic acid impregnates diatomatious earth, i.e., an earth consisting of
shells of microscopic organisms which, being hollow, are somewhat tenacious of the
disinfecting material, to form a disinfecting sand. This is standardised as to the
amount of evapourable poison contained in the mixture and is dispensed from tins
of varying size according to the capacities of the spaces to be fumigated. The
American Authorities have accepted this standardised measure in disinfestation
as satisfying their Regulations. Of course, the inherent danger of hydrocyanic acid
is not to be avoided by any means of disposal of the poisonous gas, but this sprinkling
of a sand, which evaporates its active medium, is a decided advance as regards
dangers on any barrel methods or other bulk production of the gas, avoiding, as
it does, extremely lethal concentrations of the hydrocyanic acid vapour. Justly
proud of the Rotterdansche-Lloyd vessels which trade with Java and Sumatra,
of which we saw two lying at the quays, one of them v/ith the blue peter at its fore
and later moving majestically up the Ij, the Authorities are jealous of the introduction
of insect life into the upper works and passenger accommodation of these
vessels. The " Cyclon " hydrocyanic methed of disinfestation, therefore, serves
a very useful purpose as regards these upper works. The use of this material requires
a Port Sanitary Authority disinfesting staff, though, beyond the use of a
gas mask, there is no special difficulty in the performance of a disinfestation with
" Cyclon."
An import which was in evidence in the harbours was those poles from Norway
and Sweden which by a change of vowel and return to the vertical, alternatively
with blocks of stone, natural or artificial, become the sub-stratum of all buildings.
Targe rafts of these piles were to be seen.
Holland has been raised somewhat up to water level by sand carried from
Europe by way of the Rhine and Meuse ; where these sands meet the North Sea
they are further raised well above the water level by wind and wave to form a
western bulwark of dunes. The largest industry of Holland is agriculture ; the
difficulty of finding potable water for the supply of a large town becomes evident.
It may be partly obtained from the beautifully bushed dunes, but it seems probable
that chlorination must in the future play a large part in the water supply.
The Congress changed its venue to the Hague via Leiden, by way
of canal. The reception and effort on our behalf by the Municipality of Leiden
was as gracious as interesting. The historical association of physical and moral
grit in Holland proper are fittingly exemplified in the Haarlem Meer Polder and in
the places of interest in the town examined that clay.
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