MAIL COACH ACCIDENT.—On the night of Thursday, the 23d ult., the male coach, from London to Portsmouth, was overturned, about four miles and a half on the London side of Petersfield, from being driven against a post on the side of the road. The accident must have originated either from the coachman, a very aged and bulky man, being asleep, war from his being unable to face the most violent storm of hail and rain. A gentleman of this county was the only passenger, either inside or out, and although much bruised on the side and hip, mounted one of the horses without a saddle, and only the bearing rein for a bridle, and rode on to Petersfield, procured a chaise and four for the conveyance of the mail, and medical assistance from the coachman, who was much bruised and internally injured. The road bags were all regularly delivered, and the mail reached Portsmouth about two hours after the usual time. The gentleman through whose exertions assistance was procured, at the risk of his life, thinks that his efforts might have called for some acknowledgement from the post office authorities; no thanks have, however, been offered, and he considers it an act of duty to give publicity to the thankless and uncourteous conduct he has experienced. The very brief and evasive notice of the circumstance, which appeared in the Morning Herald, of Thursday the 30th, plainly shews how much pains are taken to conceal such occurrences from the public.