Other paragraph of the considered memuar is devoted to orientation of electric currents under the influence of the globe. Ampere wanted to check already well-known effect by means of electric currents: as action of a terrestrial field influences inducement and an inclination of a magnetic needle. Experiences confirmed that Earth is the big magnet having the poles capable to affect other magnet and currents. Ampere's opinion on the direction of terrestrial electric currents was confirmed, and everything appeared in a full consent with the Amperovy theory of magnetism.
where i and i-electric currents; ds and ds-of length of elements of the conductor; r – distance between the middle of currents; and - the corners formed by current elements with the line between the middle; - a corner between elements.
Ancient (for example, Teofrast) in the 4th century BC found out that, except amber, and some other substances (gagate, onyx) are capable to gain as a result of friction properties, subsequently called the electric. However for a long time nobody compared magnetic and electric actions and did not introduce the idea of their community.
As initial material for Ampere experiences and supervision served. Experimenting, he used various methods and the equipment, since simple combinations of conductors or magnets and finishing construction enough difficult devices. Results of experiences and supervision formed for it the basis for an explanation of characteristics or properties of the phenomena, creation of the theory and the indication of possible practical conclusions. Then Ampere mathematically proved the theory stated to them; it sometimes demanded special mathematical methods, than Ampere and had to be engaged in passing. As a result Ampere created the strong basis for the new section of physics called by it electrodynamics.
The ampere accurately points to distinction between interaction of charges and interaction of currents: interaction of currents, stops with disconnection of a chain; in an electrostatics the attraction is found at interaction of heteronymic elektrichestvo, pushing away – at of the same name; at interaction of currents a picture the return: currents of one direction are attracted, and different signs – make a start. Besides, he found out that the attraction and pushing away of currents in vacuum occurs the same as in air.