Abbot Thayer had a lifetime interest in natural history as it was called then, particularly in ornithology. He studied how animals hid in plain sight in their environments. Above is an illustration from his book showing a snake hidden by its protective patterning.
In the Spanish American war he proposed a scheme for camouflaging ships that was never implemented. Years later in World War I Thayers ideas were used by the British navy. Below is an example of what was dubbed dazzle painting. The illustration below dates from the second world war, but is illustrative of the idea. Besides breaking up the outline of the ship from a distance, this camouflage was intended to confuse the range finding equipment then in use in naval artillery. Later with the invention of radar this sort of camouflage was no longer useful and zebra themed navies were repainted in gray.
Below is another illustration from his book of a rabbit hidden in the leaf mould of a forest floor.
A third illustration shows a partridge like birds coloration breaking up its outlines and hiding it from predators.
One of the ideas that Thayer espoused was Countershading. Some birds have their bodies darker on the top where more light will strike them and lighter on the bottom. This makes them harder to see because it reduces the tendency of the light to reveal their forms. This is still called the Thayer effect.
I once visited a women who I believe was related to Thayer and let me see a small model of a battleship in dazzle paint that Thayer had made and an original copy of his book. You can read that book for yourself online. Below is the link.
Concealing Coloration in the Animal Kingdom by Abbott Thayer