[See also: Cats and Dogs May See in Ultraviolet] Like the human retina, the canine retina contains other kinds of photoreceptors in addition to cones, called rods. These light receptors do not perceive color, but they are sensitive to light and dark changes, as well as shape and movement. And the ratio of rods to cones in the retina is much higher in dogs than it is in humans.
The distance between rungs, cleats, and steps shall not exceed 12 inches and shall be uniform throughout the length of the ladder. 1910.27(b)(1)(iii). The minimum clear length of rungs or cleats shall be 16 inches.
Photo 6: Set the feet firmly. Jump on the lowest rung to set the ladder firmly and to test for stability. If the ladder tips to one side, move it aside and adjust the depth of the hole. Even with the ladder at the correct angle, it can still tip sideways if the feet aren't level with each other and on solid ground.