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archieftoegang 499, inventarisnummer 227, pagina 126

used . But it was soon realised that the ' worm ' could gnaw through oak , or through
any other known wood , as indeed has remained the case until today . We have
seen that Sellius soon established that the ' worm ' was in fact a marine borer ; and
the many illustrations to his Historia , and much of the material the book contains
on /. navalis ' life cycle , is still regarded as reasonably accurate . What this mollusc
did was to grind the wood in which it made its dwelling-place , cum pasture , cum store-
cupboard , cum dining-room , with a sharp double shell rotating on its head . It
bored its way further and further into the hosting wood , which might be a pile
used to support the sea weed mat against an earth dike , or the wooden pillars and
sluice-boards used to control the fall of water from a high to a low level 1
, or
even the under-structure of water - or windmills . And the outer hulls of the
doubly-protected East and West Indiamen continued to be at risk 2
. The next step
against the ' worm ', as it continued in popular parlance to be named , was to try
to cause it to experience revulsion against woodwork treated with some kind of
jelly or paint . It is interesting to note that Daniel Gabriel Fahrenheit , of thermo-
meter fame , was residing in Amsterdam in the 1730s . He wrote to the water
authorities , as did a number of other European scientists , to suggest that wood-
work needing protection from the ' worm ', should be impregnated with a ' tinc-
ture ' of which he claimed to have the formula , which he believed would cause the
dreaded mollusc to withdraw . Unfortunately this formula escapes investigation ;
but Fahrenheit was invited to make it up and to experiment with it on some piles
sent to him at his address in Amsterdam , with results both embarrassing to
Fahrenheit and of dubious success against the ' plague ', as readers of the letter here
annexed will agree 3
. The whole episode demonstrates that at this time officials
were at their wits ' ends to cope with a problem that , whilst it remained unsolved ,
created a great deal of alarm , even hysteria , and was at the root of welfare pro-
blems difficult to solve even for the immediate sufferers , the cultivators of the
inundated polders , many of whom were tenants of rich city dwellers in South
Holland *.
Moreover , activity on the part of t . navalis soon proved not to be confined to
the coasts of North Holland and West Friesland . Actual dike-falls elsewhere do
not seem to have been so dramatic or destructive as those further north ; but so
electric had the atmosphere become that the discovery of a lesser degree of
1 Provided always that the water was salinated .
a Note that /. navalis feeds on the sugar in wood , digesting the chewed wood fibre , eating the sugar
and excreting the rest . Its bores are straight , unlike those depicted in contemporary illustrations
( see fig . 2 ). T . navalis becomes quite sizeable in tropical waters , although the bottoms of native fcraft
are protected , according to speciments in the Exeter Ship Museum , with a paste containing lime ,
which however needs to be renewed frequently .
3 See appendix .
4 One still-unsolved mystery is what happened to the moneys represented by the remitted verponding
tax in the areas rated ' calamiteuze '. It is possible that it was used to relieve refugees from uninundatedpolders , through the Deacons ' Chambers of the churches in the towns to which these people fledto
escape flooding .
Page of the ' Memorie en Sak Boeckje ' by Jan Ruyter , 1733 Photo Gem . Arch .
infestation of the woodwork in dikes near the Muiderpoort , and as far from the
Zuiderzee as Zaandam , created near-panic . Inspection of dikes in areas south of
Rotterdam , especially in the lower waters of the Lek , were also carried out , and
infestation by t . navalis noted . In what is now known as the Delta works , under-
taken to defend southern areas after the flooding of 1953 , the presence of the
mollusc has become known , and its dangerous reputation still causes local alarm
along the coast of the Oosterschelde , which is still open to the sea .
How were the measures once decided on against t . navalis to be financed ? Relief
from ' verponding ' must have diminished quite considerably the revenue of the
States of Holland . Yet it would be difficult to ensure that the revenue from this
local tax , no longer paid into the treasury of the States of Holland , would be used
for the purpose of defence against the sea , and so ultimately restore prosperity to
the stricken areas . Also , every water engineer , like the scientists and inventors
such as Fahrenheit , was busily engaged in planning to build new and better dikes ,
which would need very large capital sums obtained from sources hard to seek and
harder still to find . The two of these engineers whose names stand out were
Lakenman and Straat , neither without some experience in the field of water
defence , and both with the necessary administrative know-how to understand
what was needed to solve so large-scale a problem as getting the necessary raw
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