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The bogie carriages are unsurpassed for steadiness iv running, and consequently for personal comfort, but are, as is seen, more expensive tbau the lighter stock. The 6-wheeled stock, being smaller and lighter, is more suitable in general for light traffic, such as prevails on many of the New Zealand railways, as it affords means of running lighter trains by the greater facility it gives for adapting the size of train to the number of passengers carried. A proportion of bogie carriages would, however, be found useful and advantageous. I believe they would prove more economical if they were 10 feet longer than those imported. For economy in cost the carriages constructed with Cleminson's flexible wheel-base show well; they run with great smoothness and freedom from oscillation, and the wheels accommodate themselves to the 5-chain curves with facility. It is desirable to dispel the impression that is evidently on the writer's mind about the conditions of engineering in New Zealand. His remarks tend to implicate not only me, but others, in all sorts of objectionable practices which he enumerates, while he is apparently ignorant of the practice pursued, and certainly is so of my opinions. Under the public works policy, instituted in 1870, over 1,000 miles of railway were executed under the superintendence of Mr. John Carruthers, Mem. Inst. C.E., as Engineer-in- Chief, whose experience in the United States, Russia, India, Egypt, and Mauritius, was brought to bear. Associated with him were Mr. John Blackett, Mem. Inst. C.E., Assistant-Engineer-in-Chief, in the colony, and Messrs. Hemans and Bruce, as consulting engineers in London. The lines were carried out and equipped at an average cost of a little over £7,000 a mile. The mountainous features of both Islands, and more especially the Northern, rendered unavoidable steep grades and very sharp curves. Although there are some hundreds of miles of comparatively easy lines in the South, yet the major portion of the New Zealand railways may be said to abound with grades not flatter than 1 in 50 and cxirves of 10 chains radius, and a very large proportion has grades ranging from 1 iv 35 to 1 in 50, with 5-chain curves. rlhe permanent way generally is of 40-lb. and 52-lb. rails of Vignole's pattern, and the gauge 3 ft. 6 in. With such physical features, the use of stock with flexible wheel-base and light wheel-loads was imperative; and stock possessing the requisite features for the physical conditions of the lines and the very light traffic was introduced with due regard to economy. All the stock has central buffers. There are among others two types of English engine with Bissell bogies, one having 6 wheels coupled, with a 10-ft. base, and the other having 4 wheels coupled, with a 5-ft. base, both well adapted for the lines and traffic they are designed to work. There is also a 6-wheel coupled engine, with alO ft. 6 in. base—a type very largely in use on lengths of lines where the curves are not sharp. Some double Fairlies are in use on the worst lines, and some single Fairlies, which were procured on the advice of the late Engineer-in-Chief, Mr. Carruthers, and which perhaps are the most efficient and useful engines on the steep grades and 5-chain curves which we have. The single Fairlie is carried on one G-wheel bogie and one 4-wheel bogie. The former has a base of 6 ft. 9 in., and the latter one of 4 ft. 6 in. All the goods stock is 4-wheeled : the traffic is too light to warrant introducing 8-wheeled bogie stock. The carriage stock is 4-wheeled aud 6-wheeled; the latter has a flexible base. Recently Cleminson's flexible base has been introduced with marked success. There are no grease-boxes to the New Zealand stock. Crank-axles, double-headed rails, and inside connections are practically unknown. In the face of this, it is difficult to understand why such a long pamphlet has been written. Mr. Evans unnecessarily undertakes to instruct me in the opinions of the school of English engineers, in which I have been educated. It would be ill-judged to omit to acknowledge the services rendered by the American engineers in the application of the bogie, and in many other improvements in the construction of railway rolling-stock which they have advocated and introduced. It would be manifestly impossible to work such railways as there are in New Zealand without adopting mechanical features which also characterize the American stock to a very large extent. But while acknowledging the merits attaching to the American engineers and manufacturers, I must as yet maintain the opinion which I previously expressed, that we can obtain all we require more cheaply from England than from America. Nor do I concur in the claim made for the universal superiority of American-built engines. I do not desire to be the special pleader for obsolete practices, as the writer seems to infer. There is no reason that lam aware of why the respective countries should not produce equally good results mechanically and economically in their locomotive performances. Appended are some data respecting New Zealand practice which will bear out my statements. As I have been rather acrimoniously attacked in the performance of my duty by the writer, who has not understood my figures, I ask the favour of having this reply made a public document, and, with it, Mr. Evans's pamphlet. J. P. Maxwell, Wellington, sth May, 1880. Assoc. M. Inst. C.E.