Eighteenth Century Developments
The heat engine was the first ( and only) portable power source human society had. The idea is simple--a hot gas pushes a piston inside a cylinder, but the trick was getting the piston and cylinder to fit well enough so the gas could not leak out. No one in all recorded history could do that before the development of machine tools.
The machine tools ( the screw cutting lathe, the planer, the drill press, and the milling machine) allowed the construction of nearly any shape to nearly any level of precision. After making the steam engine possible ( the first heat engine), these tools were used to develop all the rest of the devices of our high tech culture.
The discovery of oxygen, and the development of the analytical balance (built by machine tools) which made it possible, led to chemistry as we know it. This allowed the development of new materials for the contruction of new devices and processes.
The new tools were applied immediately to the textile industry, and to transportation, since these were the most serious lacks of human society. The manufacture of clothing was totally changed by the early development of power spinning machines, power looms and the sewing machine. Transportation by railroad and steamship was as much as ten thousand times cheaper than the old way.
Transportation changes were the essence of the societal changes whic we have seen. Transportation meant the end of the shame based village culture which was the lot of almost all. Transportation is also responsible for the rise in environmental desecration, since the one responsible can be a long way from the site of the disaster.
The new chemistry made understanding of chemical reactions simple. The two main types of reaction are oxidation-reduction and acid-base-salt.
When oxygen ( or its chemical analogue) combines with a metal ( or its chemical analogue), the reaction is an oxidation. When oxygen is removed ( by being combined with carbon or another reducing agent), the reaction is a reduction. Metal ores are reduced to yield metal. Iron ore ( Iron oxide) is mixed with carbon ( a reducing agent), heated and the result is carbon dioxide and iron.
When an acid ( a sour tasting chemical) is combined with a base ( a chemical with name ending in "hydroxide") the result is a salt and water. Hydrochloric acid combines with sodium hydroxide to form sodium chloride, ordinary salt, and water.
The new chemistry led to the discovery of the electric battery. A battery is made from plates of two different metals separated by a conductive solution of water and an acid, base, or salt. A reaction like an oxidation occurs at one plate and a reaction like a reduction at the other. This causes electric current to flow if a wire connects the two types of plates together. Without the battery, electrical development was almost impossible, since there was no steady source of current.
The first discovery was that current flowing through a wire generates a magnetic force or field. This led to the telegraph ( the sender is a switch, and the reciever a coil of wire which attracts a piece of iron to make a click), the telegraph relay, and the electric motor.
The telegraph relay is a coil with a set of contacts which close when the coil gets current. By powering these contacts with a new battery, it is possible to extend the range of the telegraph signal. The relay is far more useful than the telegraph. Relays are used for lots of things. A computer could be built out of relays. It is even possible to think of the transistor as a crystalline relay.
The second discovery was that a wire in a changing magnetic field generates current. This led to the electric generator, the transformer, and the sound microphone.
The simplest form of generator was a single coil on a shaft fed by battery through slip rings with output drawn from a single stationary coil in its magnetic field. In such a generator, the current reverses direction every half turn of the shaft, creating a form of electricity called alternating current. Batteries produce current which flows the same way all the time, called direct current.
Alternating current in a coil creates a changing magnetic field with a strength proportional to the number of turns in the coil. When such a coil is wound over an output coil, voltage is generated in the output coil. The ratio of the turns of the two coils is the same as the voltage ratio. This device with two coils is called a transformer. In a generating station, the relatively low voltage out of the generator is transformed to a high voltage to be sent long distances over the hgigh voltage transmission lines. At the end user, the votage is transformed back to a low value again.
The next discovery of the new chemistry was photography. Certain salts are light sensitive. Silver bromide breaks down into free silver, and potassium dichromate renders gelatine insoluble when exposed to ultra-violet light. These salts were used to make the processes of photography and photlithography which revolutionized recording and printing.