The Swedish scientist, Mr. Karl Ellington, of Nossebro, who is basing a
book on pise (in his own tongue) upon the frail foundation of the
present volume, has, in the course of a letter to the author, made some
exceedingly suggestive "guesses at the truth."
"I am very interested to hear that you are proposing to use an hydraulic
rammer for making blocks. I have thought a good deal about this pressure
business. I am trying to scrutinise the thing from 'the inside,' so to
speak. I am trying to trace out how Nature makes rock. That helps us to
understand pise. Nature made all the stratified rocks out of what was
once fine loose earth and mud. Rivers carried the mud out to sea. Waves
pounded and gnawed the shores and got down some more stuff. The tides
went forth and back and shovelled and levelled at the sea-bottom. Some
more mud on top of that, and a few hundred or thousand feet of the heavy
water on top of that--and Nature's pise was in its making. But why do
these mud particles stick together for ever even after that stratum is
raised up high above the sea and the pressure is discontinued? That is
the counterpoint of the whole problem. What is gravitation? Is it some
form of magnetic or electric energy? We don't know. Do particles of mud
grip and hold each other if they are forced together close enough to be
united by some sort of magnetic or electric energy? Or do the particles
only get a 'mechanical' grip on each other? However that may be, we seem
to know now that we can make them grip by bringing them closely
together. It would seem important, then, that we must bring as much of
particle surfaces together within any given cubic space as we possibly
can; that is, we must have as little of 'holes,' 'empty spaces,' pores
and channels as possible in the mass, in the pressed wall. This, then,
would in turn make it important that plenty of very fine (small)
particles must be present in the mass--and so well distributed among the
coarser particles as to be on hand close by wherever there can be one
more chance for a small particle to fill a little chamber that the
coarser particles would like to bridge over. We can think of how well
Nature was fitted for this work of shuffling over all the particles at
the sea-bottom and under great water pressure till she got every
particle into the niche where it would exactly fit. She used waves,
tides, and gulf streams as shovels and mixers and packers, and the water
above as 'hydraulic rammer.' Looking at the pise matter in this way, it
would appear that both the _mixing_ and the _shuffling_ are of vital
importance. And by 'shuffling' I mean in this connection only that the
smaller and larger particles get a chance to shift over a little during
the process of pressing the earth together to hardness, so that the
pressure may not work only and exclusively in a straight downward
direction, but in a sort of wavy zigzag direction as well--much as when
a street-roller is working the macadam and gravel a little forth and
back at the same time as downward. I have a great respect for old tools
which are the outcome of long-time experience and handed-down wisdom.
I suspect the presence of some of that sort of experience in the rammer
described in your book, p. 59. That tool would do the necessary shifting
while attending to its _main_ intention: hammering the mass solidly
together downwards. Now for your hydraulic rammer--is it advisable to
make it blow or press only in a straight line downward? Maybe there
ought to be two or three kinds of strokes alternating--one stroke with a
rifled or wavy surface under the rammer--and the next stroke with a
_plane_ surface. . . . What sort of witchcraft enters into the effect of
_high frequency blows_ as compared with blows with a little longer
intervals between? Do the strokes create also some 'magnetic' effect in
the pounded earth-mass which helps to fasten the particles to each
other? And does this magnetic charge or friction heat, or whatever it
is, act more promptly if one keeps on 'striking the iron while hot,'
instead of letting the charge 'evaporate' and sneak away between
strokes? Two or three of my hairs are turning grey over these questions
alone. You compliment me by insinuating that I might stumble across some
fruitful idea for the forms or boxes if I speculate a little more on the
key-problem. Well, the thing won't leave me alone, so I have thought out
several foolish variations and rejected them too. But the last one seems
to have a little more vitality, so if it will live till I write my next
letter I will tell you about it. One is so apt to follow the temptation
of 'perfecting' an apparatus--at the cost of getting away from keeping
it cheap, simple--and 'fool-proof.' By this time the idea has grown ripe
in my mind, so that I ought to write out a little book on the pise
problem in Swedish and have it printed before springtime. Something
ought to be done. . . . I have to ask you kindly to permit me to make
use of the data contained in your book. To this I will have to add what
special precautions we must observe as to foundations in a climate like
ours. I intend to treat only the pise method. Cob and chalk methods are
not applicable here, as we have such materials only in a few unimportant
spots."
Mr. Ellington has long been an admirer and a firm friend of England, and
he is good enough to regard his country as indebted to ours for the
introduction of pise-building:
"Let me tell you that the help you are giving me now--not me, but my
nation--will work as an additional bond that draws us more closely
towards each other. . . . Some of our people here have always looked too
much towards the South and too little towards the West."
[Headnote: A Pise-Builder's School]