geological puzzle. The puzzle is often easily read; at other times this is more obscure. But read it must be unless the mine is to be made a blind gamble; and he has to be himself sufficiently of a geologist to know when and how the services of the specialist are needed. He does not want anything at all of much that the specialist delights in; but he must know the broad facts of the science well, and be as good a petrologist and mineralogist as his other duties allow. The deposit has subsequently to be worked, and the mineral won by the regular operations of the civil and mechanical engineer; limited, indeed, in treatment by the conditions of mine work, and often temporary in character, but the same in kind, subject to the same physical economic laws; and he must therefore, be instructed in the broad general principles of the engineer's art, with much special training in some branches. It is quite true that his work often must have less finish than a civil or mechanical engineer would tolerate this is because it is temporary and must pay; but, against this want of finish, must be set such a task to only take one example, as the sinking of the main-shaft of a large deep mine in wet ground, a task that may tax all the energy and skill of the specialists in all the three branches of the profession; but which must be done with the mining man as the central figure. Nowadays, he must have more than a passing acquaintance with the specialist in electrical science, and, although he must, as in previous cases, sometimes hand over a problem to the specialist for its solution, yet his own knowledge must be sufficient to keep the unity of the plan of his own work, and it should also enable him to pick the best for his own purposes out of competing solutions. In putting in underground motors, for instance, he should know what is, and what is not, suitable when presented to him, and not condemn electrical transmission because his electrical engineer was not a miner, nor electrocute his men because he is blindly trying to follow where other engineers are leading. The mining engineer, particularly when managing a property, often has to decide many purely metallurgical matters; indeed, it is very hard to say where the line can be drawn between mining and metallurgy, except, perhaps, in the extreme cases, such as those of the colliery engineer on the one side, and the mint refiner on the other; for, after all, the product of the commodity that commands the profit is not complete until the metal is extracted. Some branches of metallurgy, say that of iron, for instance, need more pure and refined mechanical engineering than any branch of mining. As far as scholastic training is concerned, it must be urged that the men need the same thorough instruction in general science, much instruction together in the main branches of the art of engineering, and it is only toward the end of a long course of work that specialisation should begin. It is generally conceded that the practical part of engineering, the power of producing skilled work, the practical bias of mind that measures all the contemplated operations as being limited by the necessity of making the best possible profit at the end can only be very imperfectly imparted, if it can be imparted at all, outside the actual field of commercial operations; it certainly cannot be imparted by those who have never been under its influence. At one time or another in his life, the engineer must learn many things for himself outside a college. He can start the acquisition of this very well before he receives the higher part of his training; indeed, there are many reasons why he should do so; but it has the drawback of tending to interrupt the mental training, unless a tax is placed upon the health of the student by compelling him to take a practical course in commercial operations just before his studies become exceedingly heavy in character. Usually, it is more convenient to defer the serious part of the instruction in practical operations until after the course. This has one great disadvantage, as that the student tends to view the world, for a long while afterwards, from a more or less false standpoint, and to bring collegiate work into unmerited disrepute, forgetful that the very best courses of study by themselves, and without practice in a profession, may make a philosopher, but will not make an engineer. The growing practice of appointing men of practical and commercial skill as well as of high mental attainment, as teachers in many of the subjects, does help the student to take the correct bias of mind, but the latter, to be safe, must remember that his college training is but his preparation for a far more serious study that must go on for years before he can claim to know his profession. He is fortunate if, during this period he is profiting by the experience of those older than himself, whom he may be assisting. A word now as to the scholastic course itself. This should be the same for those whose ambition is to manage a fair-sized mine, as for those who think that they see ahead the sweets of a consulting practice. It should include the most liberal education that can be given in the time at a student's disposal in mathematics, chemistry. descriptive geometry. mechanical drawing, geology, physics, the elements of civil and mechanical engineering. the practice of surveying, and of assaying. This purely preparatory work can be dealt with in about three years, but the courses, just as is now the case in so many technical colleges for other classes of engineers, should, if at all possible, be specially designed to fit in with the object in view, namely, to impart that systematic and useful kind of information that shall serve the mining engineer, as well as educate him in the more liberal sense. Thus, whilst much in the ordinary general science courses of universities would bear considerable strengthening, other parts could be taken in a much reduced form, and retained chiefly for the sake of educational sequence. It is purely a matter of time, and the amount that the student really needs to be taught in order to fit him for his final year's work and subsequent career. During a fourth year of study, he could then be given a severe course of professional study in mining and metallurgy. and he can then pass away from college to concern himself with practical operations. It is at this stage of the final year's work that he will profit by having taken care to acquaint himself with practical operations, even though it may have involved the loss of some holiday leisure. Men trained in this way would be eligible for very many openings in the management of the better class of mine, always provided that they will pay the same serious attention to their practical study of the manual operations that they pay to their mathematics, chemistry, or cricket. There is no need to spend a great amount of time at these studies of manual operations, provided that the student means to learn all he can, for his object is not to be a skilled rapid workman, as to know the work of one, and the circumstances surrounding it, and if it be viewed as a recreation, there is no serious drawback to time being diverted from holidays to the purpose. It must be remembered, also, that more men are wanted, well-instructed in both the practice and theory of the mining profession than a number of "mining engineers," whose acquaintance with profit and loss is rather that of the city office than the mining-field. The need of men of high training in the practical field of Australian mining is still great, and it is to the training of these men that one must look for the advancement of legitimate mining. SOME OF THE PHYSICAL PROPERTIES AND USES OF NICKEL STEEL. By W. H. WARREN, M. Inst. C.E., M. Am. Soc. C.E., Challis Professor of Engineering, University of Sydney. HISTORY. THE first suggestion for the practical application of nickel as an alloy with iron is due to Farady. In 1820 and 1821 he and Stodart made a considerable number of iron and steel alloy experiments, consisting of Swedish horseshoe-nail iron melted with 1 per cent., 3 per cent., 5 per cent., 10 per cent., 20 per cent., and 50 per cent. nickel. The metals were found to combine well, the 3 per cent. alloy being specially malleable, and working satisfactorily under the hammer. Farady's valuable experiments do not seem to have led to any commercial application in England, although they opened the way to what has since been accomplished in this direction. In 1885 nickel steel and nickel iron were manufactured at Mr. Marbeau's works at Montalaire, France, under the supervision of Mr. Berthcault. Similar results were obtained at the Imphy Works in 1887. In 1889 Mr. James Riley published his valuable paper on Alloys of Iron and Nickel," and in 1894 a length of shafting of nickel steel was constructed for the American liner Paris. In June 1895 the Pennsylvania Steel Company made a heat of about four tons of open hearth nickel steel for the purpose of investigating its physical qualities when rolled into plates and bars. The results obtained in their experiments were lower than those from nickel steel produced in the ordinary way, in consequence of the small ingots obtained from the heat not allowing for a sufficient reduction in rolling. In 1896 an investigation was made on the properties of nickel and iron alloys by Prof. M. Rudeloff, Assistant Director of the Royal Prussian Testing Department, the alloys being melted in small quantities. The results are interesting as showing the influence of varying proportions of nickel on the physical properties of the alloys, and are briefly summarized as follows: Expansion by Heat.-The coefficient of expansion by heat was found to decrease with the increase in the percentage of nickel, but was greater with the 98 per cent. nickel alloy than with pure iron, thus ... 1.000 0.943 0.891 Iron and 16 per cent. nickel... ... Tensile Strength.-The elastic limit, yield point, and ultimate breaking strength increase gradually by the addition of nickel up to 10 per cent., after which a gradual decrease takes place up to 30 per cent. With a further increase of nickel the elastic limit and yield point decrease still more, while the ultimate breaking load increases, being greater with 60 per cent. than with 30 per cent. of nickel. The elongation decreases as the percentage of nickel increases, till at 16 per cent. it is almost zero; afterwards it increases up to 60 per cent. nickel, and then again decreases. The elastic limit, yield point, and elongation of pure nickel are approximately 60 per cent. of those of pure iron, the breaking loads being about equal. Compressive Strength. The results obtained in compres sion are similar to those obtained in tension, but the resistance increases up to 16 per cent. nickel, and then decreases. Drop Tests. The results obtained in the drop test show an increase in strength up to with 16 per cent. nickel, and then a decrease until with 30 per cent. nickel it is the same as pure iron. Shearing tests gave similar results to those in tension. The following table gives the results of mechanical tests made by Mr. Hadfield and Professor J. O. Arnold* on practically pure iron and nickel: |