USEFUL INFORMATION
It may not be generally known that we have in the nickel five-cent piece of our American coinage a key to the tables of linear measures and weights. The diameter of a nickel is exactly two centimeters, and its weight is five grammes. Five nickels in a row will give the length of the decimeter, and two of them will weigh a decagram. As the kiloliter is a cubic meter, the key of the measure of length is also that of capacity.
Among the North American Indians polished shells were used as currency.
This money was called wampum and was recognized by the colonists.
Six white shells were exchanged for three purple beads, and these in
turn were equivalent to one English penny.