The book's hero is a 14-year-old Ben Franklin - which indicates that the novel was set in the year 1720, although the year in which the book's events take place is never stated. Newton's Cannon is a work of historical science fiction. Imagine what the world would have been like if Isaac Newton, during his alchemical experiments, had found a way to communicate with the aether. Newton called his creation "philosopher's mercury," not to be confused with the element mercury. This invention is effectively the same as using magic, although with a scientific basis. Thusly, Newton becomes the greatest sorcerer of his time.
Of course, where there is one sorcerer there are bound to be others. And poor Ben, who is apprenticed to his brother in the printing business, finds himself unwittingly caught in the middle of some international intrigue involving disputes between France and Great Britain. Of course, in the presence of this new-found magic, the Franklin brothers are not merely in the possession of a printing press, they have a machine which communicates over vast distances instantaneously. These machines, called aetherschreibers, aren't terribly uncommon. Such miracles are in fact fairly commonplace, and the Franklins merely use one to print up news stories "broadcast" to them from Europe. It is somewhat like our wireless transmissions, only they occur instantaneously via the aether.
Ben Franklin, being a very intellectually-minded and curious young man, begins to experiment with his brother's aetherschreiber and finds a way to "tune" the device to any "frequency," a feat that magicians had either been working on and failed at, or considered very dangerous because it makes it possible to spy on the communications of others. The latter were correct in their fears, and after Ben's innocent discovery, all hell busts loose in the novel.
The plot of Newton's Cannon is not straight-forward, but has many twists and unexpected turns of event. It was enough to keep my interest going, and that's saying quite a lot.