Exchange
2 of the 6 encyclopedias on this shelf carry an entry for Exchange. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
the act of exchanging, or giving one thing for another; or that which is so given. In commerce, a place where merchants, brokers, etc., meet to transact business; generally contracted into 'Change. ge. The institution of exchanges hanges dates from the 16th century. They originated in the important trading cities of Italy, Germany, and the Netherlands, from which last-named country they were introduced into England. In some exchanges only a special class of business is transacted. Thus there are stock exchanges, corn exchanges, coal exchanges, cotton exchanges, etc. For bill of exchange, see BILL. Course of exchange, the current price of a bill of exchange at any one place as compared with what it is at another. If for $500 at one place exactly $500 at the other must be paid, then the course of exchange between the two places is at par; if more must be paid at the second place, then it is above par at the other; if less, it is below it. Arbitration of exchange, the operation of converting the currency of any country into that of a second one by means of other currencies intervening between the two. In arithmetic, a rule for ascertaining how much of the money of one country is equivalent in value to a given amount of that of another. In law, a mutual grant of equal interests, in consideration the one for the other. Theory of exchange, a hypothesis with regard to radiant heat, devised by Prevost of Geneva, and since generally accepted. All bodies radiate heat. If two of different temperatures be placed near each other, each will radiate heat to the other, but the one higher in temperature will receive less than it emits. Finally, both will be of the same temperature, each receiving from the other precisely as much heat as it sends it in return. This scale is called the mobile equilibrium of temperature.
Aiton's Encyclopedia (1910)
. See Stock Exchange
What Has Changed in the Last Century
Collier's in 1921 defined an exchange first as a physical place "where merchants, brokers, etc., meet to transact business" — and listed corn, coal and cotton exchanges alongside stock exchanges. Almost all of those trading floors are now gone or ceremonial: the London Stock Exchange abandoned open-outcry dealing at the 1986 "Big Bang", and most of Britain's Victorian corn exchange buildings are today concert halls, markets or arts venues. The idea of a fixed "par" between two currencies, which Collier's treats as the natural benchmark, ended when the Bretton Woods system of pegged rates broke down in 1971; major currencies have floated ever since, and the foreign-exchange market now turns over trillions of dollars a day on screens rather than in rooms. The one item in the entry that has not aged at all is the physics: Prevost's theory of exchange of radiant heat, described as "since generally accepted", still is.
Written for this edition, 2026.