A few passenger carriages are occasionally built at Wolverton as experiments. One, the invention of Mr. J. M'Connel, the head of the locomotive department, effects several important improvements. It is a composite carriage of corrugated iron, lined with wood to prevent unpleasant vibration, on six wheels, the centre wheels following the leading wheels round curves by a very ingenious arrangement. This carriage holds sixty second-class passengers and fifteen first-class, beside a guard's brake, which will hold five more; all in one body. The saving in weight amounts to thirty-five per cent. A number of locomotives have lately been built from the designs of the same eminent engineer, to meet the demands of the passenger traffic in excursion trains for July and August, 1851. It must be understood that although locomotives are built at Wolverton, only a small proportion of the engines used on the line are built by the company, and the chief importance of the factory at Wolverton is as a repairing shop, and school for engine-drivers. Every engine has a number. When an engine on any part of the lines in connection with Wolverton needs repair, it is forwarded with a printed form, filled up and signed by the superintendent of the station near which the engine has been working. As thus--"Engine 60, axle of driving-wheel out of gauge, fire-box burned out," etc. This invoice or bill of particulars is copied into a sort of day-book, to be eventually transferred into the account in the ledger, in which No. 60 has a place. The superintendent next in command under the locomotive engineer-in-chief, places the lame engine in the hands of the foreman who happens to be first disengaged. The foreman sets the workmen he can spare at the needful repairs. When completed, the foreman makes a report, which is entered in the ledger, opposite the number of the engine, stating the repairs done, the men's names who did it, and how many days, hours, and quarters of an hour each man was employed. The engine reported sound is then returned to its station, with a report of the repairs which have been effected. The whole work is completed on the principle of a series of links of responsibility. The engineer-in-chief is answerable to the directors for the efficiency of the locomotives; he examines the book, and depends on his superintendent. The superintendent depends on the foreman to whom the work was entrusted; and, should the work be slurred, must bear the shame, but can turn upon the workmen he selected for the job. In fact, the whole work of this vast establishment is carried on by dividing the workmen into small companies, under the superintendence of an officer responsible for the quantity and quality of the work of his men.