Galileo, however, appears not to have met with any great measure of success in putting this idea into practice.

It remained for the mechanical ingenuity of Huyghens to construct a satisfactory pendulum clock.
As a theoretical result of the studies of rolling and oscillating bodies, there was developed what is usually spoken of as the third law of motion--namely, the law that a given force operates upon a moving body with an effect proportionate to its effect upon the same body when at rest.

Or, as Whewell states the law: "The dynamical effect of force is as the statical effect; that is, the velocity which any force generates in a given time, when it puts the body in motion, is proportional to the pressure which this same force produces in a body at rest."(2) According to the second law of motion, each one of the different forces, operating at the same time upon a moving body, produces the same effect as if it operated upon the body while at rest.
STEVINUS AND THE LAW OF EQUILIBRIUM It appears, then, that the mechanical studies of Galileo, taken as a whole, were nothing less than revolutionary.

They constituted the first great advance upon the dynamic studies of Archimedes, and then led to the secure foundation for one of the most important of modern sciences.
We shall see that an important company of students entered the field immediately after the time of Galileo, and carried forward the work he had so well begun.

But before passing on to the consideration of their labors, we must consider work in allied fields of two men who were contemporaries of Galileo and whose original labors were in some respects scarcely less important than his own.