Note 4 — Chapter VII · THE EFFECT OF ALTERATIONS TO VALVE AND ECCENTRIC.

To assure one’s self of this, take an extreme case and imagine an excessive amount of lap to be added. In such a case, with travel unaltered, the ports might not be opened to steam at all, the valve simply sliding backwards and forwards without uncovering them; now, taking this lap off piecemeal the port would first be opened to an exceedingly small degree and instantly shut again, the amount and duration of opening increasing with each successive removal of lap.