Such periods do not occur to all simultaneously, else would the great postal work of the kingdom come to a dead-lock. They are distributed so that the action of the heart never flags, even when large drafts are made on the working staff, as when a whole battalion of the employes goes out for a field-day in the garb of Volunteers. There are between eight and nine hundred men of the Post-Office, who, not content with carrying Her Majesty's mails, voluntarily carry Her Majesty's rifles. These go through the drudgery and drill of military service at odd hours, as they find time, and on high occasions they march out to the martial strains of fife and drum. On one such occasion the Post-Office battalion (better known as the 49th Middlesex) took part in a sham fight, which Phil Maylands and Peter Pax (who chanced to have holidays at the time) went out to see. They did not take part in it, not being Volunteers, but they took pride in it, as worthy, right-spirited men of the Post could not fail to do. The 49th Middlesex distinguished themselves on that occasion. Their appearance as they marched on to the battle-ground--some distance out of London--bore creditable comparison with the best corps in the service. So said Pax; and Pax was a good judge, being naturally critical. When the fight began, and the rattling musketry, to say nothing of booming artillery, created such a smoke that no unmilitary person could make head or tail of anything, the 49th Middlesex took advantage of a hollow, and executed a flank movement that would have done credit to the 42nd Highlanders, and even drew forth an approving nod and smile from the reviewing officer, who with his cocked-hatted staff witnessed the movement from an eminence which was swept by a devastating cross-fire from every part of the field. When the artillery were ordered to another eminence to check the movement and dislodge them from the hollow, the gallant 49th stood their ground in the face of a fire that would have swept that hollow as with the besom of destruction. They also replied with a continuous discharge that would, in five minutes, have immolated every man and horse on the eminence. When, afterwards, a body of cavalry was sent to teach the gallant 49th a lesson, and came thundering down on them like a wolf on the fold, or an avalanche on a Swiss hamlet, they formed square with mathematical precision, received them with a withering fire that ought to have emptied every saddle, and, with the bayonet's point, turned them trooping off to the right and left, discomfited.