[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.
2. Locate an area centered between the two joists, and cut a 6- to 8-inch-diameter hole using a keyhole saw. Remove the cut section of drywall to create an inspection hole, and reach into the hole to push aside any insulation above the drywall around the hole.ip. 1  If the attic access hole is being cut for an attic ladder, check the width of your ceiling joists. 2  If the joists are installed at 16 inches on center, you will need to cut one joist and attach a brace between the two end boards to allow for the wider width of the ladder.