Under a system of coinage, inequalities in exchange are easily adjusted, like "the boot" in a horse trade, or the balance between produce carried to the store and the articles carried away. Most of all, coin is used where for any reason there is distrust of the future. Coin, or its equivalent in bullion, is needed in all transactions where credit is wanting. This appears prominent in all lawless communities with a fluctuating population, and may be found in ignorant communities where methods of credit are not established. It is often essential in the settlement of claims between hostile countries, and is the final means of adjusting balances in all foreign trade. Occasionally this need appears in a universal panic, where each man takes his fellow by the throat, saying, "Pay me that thou owest."
_Coin a part of a country's capital._--The coined money of a country thus becomes wealth in store for constant use as a machine of exchange. Its operation is effective when it keeps in constant motion, being itself consumed very slowly in the wear and tear of motion. It is sometimes compared to an endless screw, transmitting motion to everything else with which it comes in contact. Like other machines, it may be either too abundant or too scarce for the best advantage of the country. In either case there is waste. When the coin is idle it is unproductive, but suffers less waste from deterioration than almost any other kind of machine. In case of scarcity the cost of its use is increased under the general law of supply and demand, exactly as the cost of other machinery in use is advanced when many desire to use it. This machine is a prominent part of the capital of a country, greater in some countries than in others. In France the value of coin is estimated to be 3 per cent of the value of all real estate, including buildings. The use of such a machine makes a material part of the annual cost of exchanges. The coin of England, where interest is comparatively low, costs for its use in interest, wear and tear, and re-coinage more than $20,000,000 annually.
An additional cost to individuals is in the extra risk of carrying such wealth, as shown in express charges and special insurance, and still greater expense for safe keeping, and a considerable use of time in counting. These facts have led to many devices for lessening the need of keeping wealth in this form.