"This extremely artful suggestion Mr. Barkis accompanied with a nudge of his elbow that gave me quite a stitch in my side. After that, he slouched over his horse in his usual manner; and made no other reference to the subject except, half an hour afterwards, taking a piece of chalk from his pocket, and writing up, inside the tilt of the cart, 'Clara Peggotty' - apparently as a private memorandum."

All the horse-drawn waggons used to have a vertical barrier in front of the driver's feet to protect against horses' hooves splashing mud on the driver. Many had on top of the upright barrier, a six or eight inch addition tilted forward at about forty five degrees, for increased protection.
Incidentally, the instrument panel of an automobile is still commonly called the "dash board" as a carry-over from the horse and buggy days.