lakes of Ontario and Erie to Minnesota. He argued that these plants were originally introduced by natural emigration along an ancient estuary, and that many of them remain to the present day in consequence of the existence of conditions favorable to their preservation. He supposed that the plants about the salt springs in Northern New York were introduced in the same way. The pre-glacial flora has been completely destroyed by the intense cold, and while a new creation might explain the existence of salt water plants about the springs, it would not show why these marine plants could exist in the far interior. There should be a special fitness of species to conditions, in case the creation theory is invoked. He concluded that the continent must have been submerged two or three hundred feet lower than geologists had supposed, relying upon the ordinary arguments, and that the clays about Superior and Erie must have been of marine or estuary origin. It was quite unexpected that the present distribution of plants should throw so much light upon geological questions, and therefore it was urged that botanists should faithfully preserve the localities of all their specimens.

Professor T. STERRY HUNT said the presence of black iron sand upon many sea beaches has long been noticed both in Europe and America. Their origin is to be found in the crystalline rocks, from the disintegration of which these sands have been derived. The action of the waves, by virtue of the greater specific gravity of these sands, effects a process of concentration, so that considerable layers of nearly pure black sand are often found on shores exposed to wind and tide. These black sands vary in composition according to the localities, but as found on the coast of New England and the Gulf of St. Lawrence consist of magnetic oxyd of iron, with a large admixture of titaniferous iron ore, and more or less garnet, the purest specimens holding from thirty to fifty per cent. of magnetic grains. Such sands have long been employed as sources of iron in India, where they are directly converted in small furnaces into malleable iron. Early in the last century the considerable quantities of these sands found on our Atlantic coast attracted the attention of the colonists and of scientific men in England, and the Virginia sand-iron, as it was called, was the subject of many experiments. The first successful attempts at working it were, however, made in Killingworth, Conn., where the Rev. Jabez Elliot, grandson of the celebrated John Elliot, the apostle of the Indians, early turned his attention to the abundant black sands of the coast, and succeeded in treating them in a forge fire similar to the German forge or modern American bloomary fire. It appears from his account laid before the Royal Society of London in 1761, that he was then making iron blooms of fifty pounds weight from this ore, and that his son had already established a steel factory in Killingworth, when an act of the British Parliament forbade the manufacture of steel in the colonies. The London Society of Arts in 1761 awarded a medal to Mr. Elliot for his discovery. The working, however, was abandoned, and for a century no attempts were made in America to use these sands. Some four years

since the large quantities of them in the lower St. Lawrence attracted attention, and successful trials were made for their reduction in the bloomary fires of Northern New York, after which an establishment for working them was erected at Moisie in the Gulf of St. Lawrence, where, under the direction of skilled workmen from Lake Champlain, the treatment of these iron sands has been successfully carried on. These sand ores are remarkably free from both sulphur and phosphorus, and hence yield an iron of great purity and toughness. The working is effected in forges like those used on Lake Champlain, and presents no difficulties.

Prof. W. C. KERR remarked "On some points in the Stratigraphy and Surface Geology of North Carolina." The two long narrow belts (troughs) of coal-bearing triassic rocks in North Carolina, lying, nearly parallel, in a direction a little north of east, and separated by an elevated and rolling tract of metamorphic and granite rocks fifty to seventy-five miles wide, are found to constitute the fragmentary fringes of an eroded anticlinal, the one dipping north-west at an angle of 30° to 75°, the other south-east 10° to 35°. The material of this formation was furnished mainly by an ancient plateau or mountain chain lying castward, between the mesozoic and the Atlantic, which "has left no sign" of its existence but this. I have found no trace of glacial action in North Carolina, even in the most elevated mountain plateaus, but abundance of Quaternary gravels, whose position is such as to negative the existence of glaciers in this latitude. Among these deposits occurs a remarkable peat bed, fifteen feet thick and about one hundred yards long, recently exposed in a railroad cut. Its position is very peculiar, at an elevation of more than one thousand feet above the sea, and near the top of a hill one hundred feet above the valley of the Catawba River (which is one mile distant), and twenty-five miles from the Blue Ridge. It is covered and protected by eight to ten feet of fluvial gravel and sand. It is peculiar also in its contents, being made up in considerable part of drift wood, and containing abundance of pine and hemlock cones (there being no hemlock forests nearer than the Blue Ridge) and other seeds, and also of charcoal, partially burned piae knots and charred logs.

Another peculiarity is that the peat, occupying the middle of the nearly vertical face of the cut (some eighty feet deep), and being exposed but one season, has put forth an abundant swamp vegetation, consisting of carex, juncus, and several species of swamp grass and weeds.

There are evidences in eastern North Carolina of considerable oscillations of sea level during the prehuman period (probably synchronous with the Champlain epoch). The accumulations of stratified gravels on the summits and slopes of the hills, at an elevation of more than three hundred feet above the present sea level, extending entirely across the State, at a distance of one hundred and twenty-five to one hundred and fifty miles from the coast, indicate the extent of this movement in one direction, while the minimum of elevation is indicated by the excavation of the channel of the Cape Fear River (e. g.) for more than thirty miles to a depth exceeding one hundred feet below the present tide level.

Professor W. C. KERR on the "Probable Origin of the South Carolina Phosphates." The physical circumstances of the deposition of these beds in their present situation, have been explained in a manner sufficiently probable by Professor Pratt of Charleston; but I have seen no suggestion which is at all adequate to account for the origin of the materials which compose them, the elimination and accumulation of such enormous quantities of phosphate of lime in so peculiar a situation.

The recent discovery of the singular Brachiopod, Lingula pyramidata, in the shoals along the sounds of North and South Carolina furnish a solution of the mystery. This shell, it will be remembered, consists of phosphate instead of carbonate of lime. Its habitat is at the precise level of the Ashley River phosphates, and the shell being very fragile and left. within the play of the tides in the shifting sand of the shoals, rapidly loses its form and furnishes only its solid material, to be agglomerated by some concretionary or other chemical or chemico-mechanical force into the nodular masses which are so peculiar to this formation.

THE MICROSCOPICAL SUBSECTION OF THE AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE, which was initiated at the Salem meeting last year, was continued with renewed interest and increased numbers at the Troy meeting this summer, and promises to be a permanent and useful division of the Association. Under the Constitution, as amended this year, this department is removed from Section B (Natural History), and recognized as Subsection C of Section A (Mathematics and Physics). This arrangement, though somewhat confusing, is probably the most convenient that could have been made; microscopy proper, the science of the instrument, belonging strictly to mathematics and physics - but microscopy applied, the use of the instrument, being chiefly a department of Natural History. To avoid confusion at this point, authors of Natural History papers designed for this department should make a memorandum to that effect upon their MSS., as a request to the standing committee to assign them to Section A instead of Section B.

Professor S. S. HALDEMAN, of Columbia, Pennsylvania, was elected Permanent Chairman this year; and Dr. R. H. WARD, of Troy, N. Y., Secretary.

Although this subsection, having been recently formed, has necessarily been much occupied with the details of its own organization, it has already done much work and contributed some valuable papers, among which were the following, of which abstracts are published elsewhere: "On a new form of Binocular Microscope," by President F. A. P. Barnard, of Columbia College, N. Y., describing elaborately a newly contrived instrument in which the light is separated into two pencils by double refraction, and which cannot fail to be a valuable addition to the resources of the working microscopist; and "on the Illumination of Binocular Microscopes," by Dr. R. H. Ward, of Troy, suggesting convenient means of regulating illumination in the naturalist's every day work with the microscope, and urging that professional microscopists make their influence

more distinctly felt in regard to the lower classes of instruments that are furnished to beginners, and particularly in regard to popularizing the Binocular Microscope.

Fig. 100.

In exhibiting photographs by Dr. Maddox of the Podura scale, President Barnard gave an exhaustive review of the discussion in regard to the structure of the scale. The traditional "note of exclamation," or goosequill markings are unlike those of any other known scale, and many naturalists are anxious, on grounds of analogy, to get rid of them. Mr. Beck argued that these marks represented parallel lines on different sides of the scale, crossing each other at an acute angle, and necessarily imperfectly focussed; some observers have attributed them to corrugations or folded ridges of the upper and lower membranes of the scale; and Mr. Pigott, with his aplanatic searcher, and others have seemed to resolve them into bead-like rows of spherules, between two membranes. The use of reflected light to determine these points is very desirable, but difficult with sufficiently high powers. Professor Smith, of Kenyon College, proposed to make the objective its own illuminator. Others have replaced the mirror he placed behind the lenses by a plate of glass or a prism; but all these means give a glare'of light by reflection from the surfaces of the lenses. The speaker had proposed a concave mirror behind the outer pair, an internal Lieberkuhn (fig. 100) which works exceedingly well with medium powers, say one-third or one-fourth inch; but there is not room for its insertion in high powers. As compared with Tolles' prism, which is similarly situated (above the front pair), it gives more light, and illuminates from any part or all parts of the circumference at will; on the other hand it is less easily applied, requiring the front lens to be mounted in glass instead of brass, and it is inapplicable to large opaque objects. The beaded appearance has not yet been satisfactorily seen by reflected light; nor is it well shown in the photographs where the wedgeshaped dashes seem rather marked by crosslines or partial interruptions. The speaker evidently doubted the accuracy of the exclamation points, but was not yet ready to accept the beads. Appearances best seen by pushing an objective far beyond its ordinary power were received with general distrust.

DDR

In the discussion which followed the reading of this paper, Dr. Ward remarked that the production of a beaded appearance, as a purely optical effect, should be considered no longer doubtful, but rather an occasional accident to persons using high powers. As an extreme instance, in the case of a coarse and familiar structure, he related that while experimenting upon an elater of Marchantia polymorpha, that beautiful double spiral

was "resolved" into three rows of "beads" or "hemispheres," perfectly distinct and unmistakable, which occupied, of course, the position of the middle and edges of the spiral. They were illuminated by parallel light, very oblique, under a 1-15 objective of 175° worked at a power of 3,000 diameters.

Mr. E. Bicknell, of the Museum of Comparative Zoology at Cambridge, Mass., exhibited some diatoms recently thrown up by the sea at Marblehead, Mass. The deposit first found belonged to brackish water, as indicated by the nature of the diatoms and the presence of fruit of the Characea. The second deposit occurred about a mile from the first, and was purely of fresh-water origin; consisting of peat with fresh-water diatoms, Pinnularia, Stauroneis, Navicula rhomboides, N. serians, etc. These deposits were thrown up by a severe storm on the 31st of March last, and are believed to be the first fresh-water or brackish deposits known to exist under the present ocean. They seem to be conclusive proof of the recent encroachments of the ocean upon the shore-line in that vicinity.

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The Test Plate of Nobert, who has now 'gone to the war," and Dr. Woodward's photographs of the same, were exhibited by Dr. Ward, chiefly in the interest of that part of the audience who were not professional microscopists, and might be unfamiliar with these wonderful works of human art. Until a year or two ago the finest lines had never been seen, even by the maker of them; now they have been seen by many persons, and have been photographed. He was now satisfied, for the first time, after hearing Mr. Bicknell's description, that the Boston microscopists had seen the genuine lines with powers of only five or six hundred diameters. In regard to the use of photography as a test of structure under high powers and difficult circumstances, we may learn a lesson from the broad bands of light and shade in the photograph of the coarser lines, which manifestly have no resemblance to the appearance of scratches on glass as seen under suitable powers.

Dr. Ward had also been investigating the effect of seeing two planes of the object at the same time with the Wenham's Binocular. The eye-pieces being practically not equidistant from the objective, the corresponding conjugate foci below do not coincide. Some microscopists have attributed much of the stereoscopic effect to this fact, which, however, does not seem to contribute perceptibly (except in the lowest powers, where the angular stereoscopic effect is necessarily very small, and where this difference of planes is most considerable), either to the stereoscopic effect, or to the increased distinctness of definition above and below the plane of most perfect vision.

An abundance of instruments were furnished by members to illustrate their discussions, or for the general work of the subsection. The first class stands were mostly of the make of Powell and Leland, and Beck, and Crouch, of London, of Nachèt of Paris, and of Zentmeyer in this country. The "Jackson" model of stand, with a curved arm, seems to be