In  the context of the fourth annual polar year, the explorer Jean Louis Etienne, with the participation of large numbers of partners and sponsors,  pilots the Total Pole Airship expedition.

The primary objectives of this expedition are  to measure the thickness of the polar ice floe (sea ice) in order to measure the effects of global warming, and to establish a point of reference for future studies. In addition, an attempt is to be made  to measure the  precise positions of the North Magnetic Pole,  and the magnetic field of the Arctic Ocean.

These measurements were supposed to take place during April and May 2008, when the thickness of the sea ice is at its greatest, but the dirigible was destroyed in January, 2008.

The four stroke engine is an internal or heat combustion engine commonly used to power transport vehicles. The complete cycle requires four successive phases. During the intake stroke, a fuel-air mixture is drawn into the cylinder. It is then compressed by the upward movement of a piston. The mixture is ignited by a spark plug to initiate the combustion stroke, the source of power, and finally the spent gases are forced out during the exhaust stroke. The cycle repeats itself over and over again.

Animation brought to you in cooperation with the Musée des Arts et Métiers - Paris.

The velocipede (literally "fast foot") uses a chain set with a fixed sprocket on the front wheel: one turn of the pedals is the equivalent of one turn of the driving wheel.

To travel greater distances with each turn of the pedals it is necessary to increase the diameter of the front wheel: the Penny Farthing is an extreme application of this principle.

The bicycle uses a transmission system that involves a chain connecting two sprockets of different sizes, which provides greater distance to be covered with each turn of the pedals.

An electrical circuit consists of :

• At least two components (also called dipoles because they have two poles) one of which is the generator (also referred to as the source).
• Conducting wires that connect the components to form a closed loop that enables current to flow.

Numerous forms of transpoort operate using electrical energy. Regardless of the dipole used, an electric motor is connected to the generator (not shown in the photos) by two conducting wires.

The electric power available at the terminals of a dipole is equal to the product of the current (I, in amperes, or "amps") and the voltage (E, for "electromotive force", in volts).

Remark: The colors chosen are not the conventional ones. The voltage and the current  could be direct or alternating.

Animation brought to you in cooperation with the Musée des Arts et Métiers - Paris.

The velocipede (literally "fast foot") uses a chain set with a fixed sprocket on the front wheel: one turn of the pedals is the equivalent of one turn of the driving wheel.

To travel greater distances with each turn of the pedals it is necessary to increase the diameter of the front wheel: the Penny Farthing is an extreme application of this principle.

The bicycle uses a transmission system that involves a chain connecting two sprockets of different sizes, which provides greater distance to be covered with each turn of the pedals.

Brought to you in cooperation with the Musée des Arts et Metiers - Paris.

A gear system is one involved in the transmission of motion. The two toothed wheels  assure a driving force without slippage.  In these four systems,  the driving wheel (at top) turns at a constant speed.

• First case: the "Maltese Cross " system transforms the contiunuous rotation into discontinuous motion: this is a turn counter.
• Other cases: the variable speed of the lower wheel is determined by the wheel's geometry.

Animation brought to you in cooperation with the Musée des Arts et Métiers - Paris.

The velocipede (literally "fast foot") uses a chain set with a fixed sprocket on the front wheel: one turn of the pedals is the equivalent of one turn of the driving wheel.

To travel greater distances with each turn of the pedals it is necessary to increase the diameter of the front wheel: the Penny Farthing is an extreme application of this principle.

The bicycle uses a transmission system that involves a chain connecting two sprockets of different sizes, which provides greater distance to be covered with each turn of the pedals.

A gear system enables the transmission of motion. In this example, which deals exclusively  with toothed wheels, only rotational motion is dealt with.  The speeds of rotation are a function of the gear ratio (or transmission ratio), which depends solely on the number of teeth on each wheel.

Knowing that the number of teeth is proportional to the wheel's diameter, we can also define the gear ratio as a function of wheel diameters.

A gear system ensures  a transmission without slippage, and with a very high yield. The gear ratio can be greater than 1 (muliplication) or less than 1 (reduction).  Augmentation of the couple  produces a decreased speed, and vice versa.

An electric motor converts electrical energy into mechanical energy. The innovation lies in the production of a rotating magnetic field from fixed armature windings with a sinusoidal voltage frequency running through them. Nikola Tesla perfected the uses of this device, resulting in his 1888 invention of the first three-phase electric motor.

Such motors are now everywhere: they are in trains, in washing machines, in factories...

Note that these machines are reversible, that is, that you can also convert mechanical energy into electrical energy. That's what happens in power plants. The machines used in power plants are called generators, or alternators.