The year 1698 in science and technology involved some significant events.
Astronomy
Christiaan Huygens, in his posthumously published book Kosmotheoros, argues that other planets in the Solar System could contain extraterrestrial life, starting a debate that extends into the 21st century.
The piano is invented by Italian Bartolomeo Cristofori, originally named the "piano et forte" (meaning "soft and loud").
A metronome is developed as a machine to measure musical tempo.
Events
November – Tani Jinzan, astronomer and calendar scholar, observes a fire destroy Tosa in Japan at the same time as a Leonidmeteor shower, taking it as evidence to reinforce belief in the "Theory of Areas".