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resemblance to certain fossiliferous sandstones at Kawhia of Jurassic and Triassic age would tend to show that they are probably not older than Secondary. Of the extent and probable distribution of the granitic rocks it is perhaps even more difficult to speak, as their outcrop is covered by younger formations. The numerous varieties of crystalline rocks found in the conglomerate would lead to the belief that a considerable area of these rocks must have been subject to sub-aerial erosion in order to supply the material. It is at any rate permissible to suppose that a floor of granite and granitoid rocks extends throughout the central portion of this Island, and this hypothesis would harmonise with and perhaps explain the highly acidic character of the volcanic outbursts which have devastated that area throughout later Tertiary times. The south-west dip of the argillaceous sandstones at the Ngutunui and westerly dip at the Mangaone Falls, near the outcrop of the granite conglomerate, would favour the extension of the granites to the eastward or inland side of Pirongia and the Hauturu Ranges rather than to the seaward side, since the dip would naturally be away from, not towards, the older rocks. " Granites are often of an eruptive character, and in Scotland they have been found of Tertiary age penetrating Jurassic rocks (Geikie's Textbook, page 140), but none younger than Silurian have been shown to exist in New Zealand, and those in the Upper Waipa Valley are no doubt as ancient as the Lower Silurian granites and gneiss rocks of the Pikikiruna and Mount Arthur Ranges. "Hitherto no granite or crystalline rock of any kind has been known to exist in the North Island, and this may be regarded as the most important geological discovery of the past thirty years. The discovery is not only unique and interesting from a geological and scientific point of view, but it also possesses an important bearing of an economic kind. Granite and allied rocks are well known as the constant associates of tin-ores, and although no tin has so far been found in the Waipa district, it is possible that a search of the broken unexplored country lying west of the Hauturu Range may disclose the presence of tin or other deposits of valuable ores."

MINING MACHINERY. Luhrig's Ore-dressing and Concentrating Plant. Some two years ago Mr. J. Cosmo Newbery, Metallurgist to the Victorian Government, was sent to Europe at the instance of the Mines Department of Victoria, to inquire into and report on the best methods of treating metalliferous ores, and the system he has advocated since his return to the colonies is a plant designed and patented by C. Liihrig, Mining and Ore-dressing Engineer, Dresden, Saxony. Since Mr. Newbery's visit to Germany this machinery has been patented in this colony, and the general adoption of the term " Luhrig's Process " has given rise to much discontent and jealousy among other inventors, whose ideas are embodied in the combination of the plant and system Mr. Liihrig has patented as his own ; and it is a question yet that remains to be seen whether this system of concentration can be carried out more effectually and more economically than that which is done at the plant erected at the Sylvia Company's works at Tararu Creek, in the Thames District, which is certainly the best concentrating-plant yet in use in any of the Australasian Colonies. During last year I communicated with Mr. Liihrig with the view of having a full description of his plant, and received letters from him as well as the company in London which has purchased the patent rights in the colony, who referred me to Mr. J. Cosmo Newberry, of Victoria, who is agent for the colonies, for full information, which has not yet come to hand; but in a letter from the secretary of the company in London, dated the 29th April last, he states that an order for a perfect and complete plant has been given the Liihrig Company for New Zealand, and that it will be shipped for New Zealand within two months from the date of his letter, and that pamphlets containing a full description of the process will be forwarded to me. These have not yet come to hand. Several descriptions of the process have appeared in several newspapers, and remarks as to the contentions raised by those who claim to have invented part of the process. On this subject the Australian Mining Standard says,— " Such contentions, however, have nothing to do with Australians, whose only anxiety in the matter is as to adaptation of it for use in the colonies. Herr Liihrig, at all events, has identified himself with it, having made from time to time all the necessary tests; and that he is a man of immense energy and capabilities is evident when it appears that, in spite of the hard struggle for existence which a working-man has to face in the Old World, and particularly, perhaps, in Germany, he has raised himself from the ranks to the position he now occupies. One Liihrig plant is not necessarily the counterpart of another, for it is exactly in the rearrangement of machinery to suit every class of ore that Herr Liihrig has achieved his successes. Thus, for instance, it was not at once apparent that the tailings taken to Germany by Mr. Newbery could be profitably dealt with. The first time the vanner was tried with them it failed entirely; but after due consideration of their composition, and subsequent alteration of inclination of table, speed, feed, and water, a most satisfactory result was obtained—namely, 80 to 90 per cent, of assay contents from 3dwt. stuff." Again, in subsequent editions of the same paper, appear the following description of the new Liihrig concentrating-plant erected at the Himmelfahrt Mine, near Freiberg, in Saxony, written by Oberbergrath O. Belhartz :— " The new central concentrating plant, which has been in constant use since October, 1889, owes its origin to the necessity of combining the five old-fashioned washers which were formerly all separate at Himmelfahrt, and therefore doing away with unnecessary transport of ore, and also of introducing at the same time a continuous method of working, which would combine all the latest improvements as regards economy in working, cost of labour, transport, &c. The present site of the plant was not selected on account of its being in the neighbourhood of the River Mulde, but, firstly