James Watt

J ames Watt, (19 January 1736 – 25 August 1819) was a Scottish inventor and mechanical engineer whose improvements to the Newcomen steam engine were fundamental to the world.

While working as an instrument maker at the University of Glasgow, Watt became interested in the technology of steam engines. He realised that contemporary engine designs wasted a great deal of energy by repeatedly cooling and re-heating the cylinder. Watt introduced a design enhancement, the separate condenser, which avoided this waste of energy and radically improved the power, efficiency, and cost-effectiveness of steam engines. He developed the concept of horsepower. The SI unit of power, the watt, was named after him.

Over the next six years, he made a number of other improvements and modifications to the steam engine. A double acting engine, in which the steam acted alternately on the two sides of the piston was one. He described methods for working the steam ‘expansively’ (i.e., using steam at pressures well above atmospheric). A compound engine, which connected two or more engines was described. Another important invention, one of which Watt was most proud of, was the Parallel motion which was essential in double-acting engines as it produced the straight line motion required for the cylinder rod and pump, from the connected rocking beam, whose end moves in a circular arc.

Because of the danger of exploding boilers, which were in a very primitive stage of development, and the ongoing issues with leaks, Watt restricted his use of high pressure steam – all of his engines used steam at near atmospheric pressure.

Watt continued to invent other things before and during his semi-retirement. He invented a new method of measuring distances by telescope, improvements in the oil lamp, a steam mangle and a machine for copying sculptures. Within his home in Handsworth Heath, Staffordshire, Watt made use of a garret room as a workshop, and it was here that he worked on many of his inventions.

André-Marie Ampère

A ndré-Marie Ampère (20 January 1775 – 10 June 1836) was a French physicist and mathematician who is generally regarded as one of the main discoverers of electromagnetism. The SI unit of measurement of electric current, the ampere, is named after him.

Ampère was born in Lyon, France on 20 January 1775. His father began to teach him Latin, until he discovered the boy’s preference and aptitude for mathematical studies.

Ampère’s fame mainly rests on his establishing the relations between electricity and magnetism, and in developing the science of electromagnetism, or, as he called it, electrodynamics. On 11 September 1820 he heard of H. C. Ørsted’s discovery that a magnetic needle is acted on by a voltaic current. Only a week later, on 18 September, Ampère presented a paper to the Academy containing a much more complete exposition of that and kindred phenomena. On the same day, Ampère also demonstrated before the Academy that parallel wires carrying currents attract or repel each other, depending on whether currents are in the same (attraction) or in opposite directions (repulsion). This laid the foundation of electrodynamics. Ampère was appointed professor of mathematics at the University of Lyon.

The topic of electromagnetism thus begun, Ampère developed a mathematical theory which not only described the electromagnetic phenomena already observed, but also predicted many new ones.