Before the 17th century, it was almost impossible to measure most things precisely. Although length and mass could be measured quite well, chemists did not realize the power of the balance, which was used primarily by assayers.
Time could only be measured in large intervals. Temperature and fluid pressure could not be measured in numbers at all. Galileo was at the heart of changing this situation.
In 1581, when he was only 16, he noticed that the period of a pendulum appeared to be controlled solely by its length. This discovery led to the manufacture of good pendulum clocks by the end of the 17th century. Galileo himself had to time some of his physics experiments with his own pulse, however. In 1586, Galileo published his invention of a hydrostatic balance.
In 1600, Galileo built the first primitive tool for measuring temperature. This was refined into a workable thermometer over the course of the 17th century and put into modern form by Fahrenheit in 1714. It was Galileo who suggested to Torricelli the investigation that led to the barometer. Galileo’s telescopes inspired others to build astronomical telescopes, which in turn led to the micrometer.
Telescopes used in surveying also inspired the vernier system for making accurate measurements of angles. None of these tools for measurement was sufficiently accurate to contribute to the development of science in Galileo’s lifetime. Shortly after his death in 1642, however, the new tools helped create modern science.