OF GALILEO.

from the previous page: ...and the conclusions of his could be called a new science; for although some of the conclusions have been observed (and what is more important) proven from their primary and undoubted foundations with necessary demonstrations. And because, as I say, I wish to satisfy you demonstratively, and not persuade you with merely probable arguments; assuming that you have that knowledge of the Mechanical conclusions already fundamentally treated by others, which will be necessary for our needs; it is fitting that before anything else we consider what effect occurs in the breaking of a piece of wood, or another solid, whose parts are firmly attached; because this is the first notion, in which consists the first and simple principle, which as most well-known it is appropriate to assume. For a clearer explanation of which: let us designate the Cy-

A diagram depicts a vertical cylinder suspended from a block of masonry. The cylinder is labeled 'A' at the top and 'B' at the bottom. A hook is attached to the bottom (B), from which hangs a heavy weight labeled 'C'. This illustrates tensile strength and the breaking point of materials under stress.

linder, or Prism A B of wood, or of other solid and coherent material, fixed from above at A, and hanging plumb, to which at the other extremity B is attached the weight C; it is manifest that whatever the tenacity and coherence between the parts of said solid may be, provided it is not infinite, it could be overcome by the force of the pulling weight C: whose gravity I posit can be increased as much as we please, and said solid will finally tear like a rope: and just as in a rope we understand its resistance to derive from the multitude of hemp filaments that compose it, so in wood one observes its fibers and filaments stretched lengthwise, which make it significantly more resistant to tearing than would be any rope of the same thickness: but in the cylinder of stone or metal the coherence (which even seems greater) of its parts depends on other glue than filaments or fibers, and yet they too are broken by a forceful pulling.

Simp. If the business proceeds as you say, I understand well that the filaments in the wood, which are as long as the wood itself, can