SEPTA cab signal display for the 4-aspect PRR system using position light aspects. Pulse code cab signaling is a form of cab signaling technology developed in the United States by the Union Switch and Signal corporation for the Pennsylvania Railroad in the 1920s.
Measuring your Saddle Seat Size. The easiest way to measure for the appropriate seat size is to measure your upper thigh. Sit in a chair with your feet flat on the ground so that your knees are bent at a 45-degree angle. Be sure your buttocks are touching the back of the chair. Take a measuring tape and run it along your thigh bone, measuring from the end of your knee to the backside of your buttocks.
Measuring a Horse. When measuring your horse, you can use either a special tape or stick delineated in hands, or a conventional measuring device. If you're using the latter, convert the number of inches into hands by dividing by 4. Place your horse on an even surface for measuring. You'll measure him from the ground to the top of his withers -- the highest point of his shoulders -- usually coinciding with the last hairs of the mane.