A communication in the _Civil Service Gazette_ states the case of a letter-carrier, in the Derby district, who has to walk above 20 miles a day, and deliver letters at eleven villages. This amount of walking exercise, allowing 15 minutes for delivery at each village, and 25 minutes for refreshment, the writer calculates to be 8 miles an hour for 2½ hours. It reads like an achievement of running a fabulous distance and picking up an incredible number of stones with the mouth. That a man might match himself to attempt such a feat of pedestrianism for a limited period and high stakes is conceivable: but this one does it daily for 11s. Of course he has sent in his resignation; no free agent could continue to do such work on such terms. Only eleven shillings for all this hard labour! Hard labour. These two words are brilliantly suggestive--seem to flash upon us the settlement of the convict employment question. Hard labour--occupation toilsome and unremunerative; at the same time useful: just the proper occupation for criminals. Rig out all our rogues and thieves in blue and scarlet, turn them into postmen, and give them six months, or upwards, of 8 miles an hour for several hours daily letter-carrying. MERCURY in Windsor uniform; messenger and thief in one: on the turnpike treadmill--'tis a pretty idea, too, into the bargain. But here up starts the difficulty. It is peculiarly necessary that a postman should, before all things, be honest. By this trifling obstacle is the magnificently specious scheme of substituting Post Office employment for the treadmill frustrated. The mounted police, and other constabulary, might prevent the fellows from escaping, and keep them in their routes; but could hardly hinder them from secreting money and notes in stumps of trees, old walls, and other nooks and corners, for concealment therein till the expiration of their sentences. Whilst, however, there exists this objection to the employment of rogues as postmen, there is nothing whatever to forbid them from employing themselves in that capacity. Hence the frequent abstraction of half-sovereigns from letters; taxing the detective acumen of MR. SCULTHORPE. We see that a bumpkin of a Post Office messenger was tried the other day at the assizes for making away with letters. He was an ignorant clown: and he destroyed them simply that he might not have the trouble of delivering them. Alas for our economy! Unfortunately we can't give inadequate wages without being in danger of getting either a knave for our servant or a fool. So we didn't quite set the Thames on fire; it won't do to make letter-carriers of convicts: and as to the nuisance of having knaves and fools amongst our postmen, there is evidently no help for that but to raise the postmen's salaries. * * * * * DEVOTEES IN CELLS.