5
September 2013 -- A boy in Don Bosco's class would
have known,
from the chapter on 'Subtraction' in his textbook, that you
can't take
5 apples from 6 pears, because his teacher, who wrote the
textbook, had
told him that "just as numbers of different species cannot be
added,
nor can they be subtracted". Mind you, many of the boys in
that class
might have thought to themselves: "Yes, but I can certainly
take five
apples from three of the neighbour' trees!" Not so fast
- the
textbook possibly had an answer to that one too, since not a
few of its
examples also involved a moral lesson. Metrics and morals!
Like one of
the exercises on multiplication: "A boy spends 2 francs a week
on
tobacco and 5 on billiards. How much would he save in a year
if he
abstained from these vices?"
Welcome to "The
Arithmetic
and Metric Decimal System Made Simple.....", 7th
edition. For the first time in English. This textbook
from Don
Bosco's hand is a real charmer. You may even learn something
as you
read it! Did you know that the unit of length (metre)
was based
on the earth, while the unit of weight (gram) was based on
water?
Napoleon's invading armies and various annexations of
territory to the
French Empire had ensured the introduction of the metric
system which
they had 'invented' or at least systematised. But it was
unpopular with
the masses and there was resistance. In fact during the
Restoration
much of Italy had abolished it. But in 1845 the Kingdom
of
Sardinia and Piedmont issued a special decree - 11th Spetember
1845,
(so we are almost at the 168th anniversary!) - to reintroduce
it,
making it obligatory by 1850. It was during these five
years that
Don Bosco got to work on his textbook - 1846 the first
edition, 1849
the second edition. His aim was to ensure that the ordinary
people,
especially rural folk and his boys who could be manipulated by
dishonest employers, could be true citizens and share in
social and
economic life. This textbook, which by its final edition
included
arithmetic, the metric system, geometry, solid geometry, and
conversion
charts, was one of his ways of doing it. As he points out in
it: "The
diversity of weights and measures is open to error and unfair
manipulation".
The approach Don Bosco adopted is typical of him: dialogue
form,
Q&A. When he gets to the 'decimal' part (after explaining
to his
readers what a base ten system is, a base twelve, and so on),
there are
a few measures that we might not recognise today, though we
can work
most of them out: we don't use the myriagram
(though we know that myriads of things are plenty indeed), and
we might
have problems with the stero
(cubic metre), but we can work out the ara 100, sq. metres
because we have
hectares today. Hectare was not a measure in use then, but had
Don
Bosco wanted to include it, his dialogue would have continued
something
like this:
Q: How big is a hectare?
A: 10 000 square metres.
Q: How big is that?
A: It is the equivalent of a square, each side having a length
of 100
m. etc.
You will discover some interesting supplementary knowledge:
from his
examples you get an idea of Turin's population, will know (if
you
didn't already) that Arabic numerals are also called Indian,
because it
is possible the Arabs got them from India. You will see that
as well as
boys saving money on vices, good citizens put aside money to
restore
churches and give alms to the poor.
The texbook includes only serious stuff - the metric decimal
system was
not something to joke about - not for the textbook at least,
but he did
have some fun with it by writing a short comedy on the topic
(translation not available as yet). His good friend Ferrante
Aporti
claimed this was a stroke of genius - getting people to learn
while
they laugh!
Which probably allows us to end on a lighter note. After
reading
this textbook, do you still have trouble with metric
conversions?
Try learning them this way:
1 million microphones = 1 megaphone
2000 mockingbirds = two kilo-mockingbirds
10 cards = 1 decacards
1 millionth of a fish = 1 microfiche
1/1000 mentals = 1 centimental
1 trillion pins = 1 terrapin
10 rations = 1 decoration
10 millipedes = 1 centipede
2 monograms = 1 diagram
2 wharves = 1 paradox
1 billion questions = 1 giga-what
And then there's the one about a certain American President
who was
distraught when he heard that 3 Brazilian soldiers were killed
in
Baghdad. "My God!", he cried."How many in a Brazillion?"
