studies of the Saxon Granulit-Gebirge was led to believe that certain of the Saxon rocks which closely resemble some members of this class, represent altered sediments, on account of their resemblance to certain contact products. Further study, however, is needed before any very definite conclusions can be arrived at concerning these members of the Laurentian in Canada.

It may be said, therefore, without going beyond that which the facts warrant, that there are in the district under consideration at least two distinct sets of foliated rocks. One of these comprising limestone, quartzites and certain garnetiferous or sillimanite gneisses, represent in all probability highly altered and extremely ancient sediments. The other set intimately

associated with these are of igneous origin, and comprise numerous and very extensive intrusions both acid and basic in character which were probably injected at widely separated times. Those masses which were first intruded and have been subjected to all the subsequent squeezing and metamorphism are now represented by well defined and apparently interstratified augen-gneisses and granulites, others intruded at later periods though showing the effects of pressure retain more or less of their massive character, while still others, which as has been shown, have been injected since all movements ceased, are recognized by all as undoubted igneous intrusions. Further more the limestones, quartzites and sedimentary gneisses above mentioned are in this area distributed through the Grenville Series, being met with in various parts of the district, occurring at what appear to be various horizons and are separated by gneisses of igneous origin or by great bodies of pyroxenic or other gneisses whose origin is yet doubtful, the whole being so intimately associated that it has been found impossible in most cases to separate them in mapping.

The Grenville Series therefore comprises certain primeval sediments which have been deeply buried, invaded by great masses of igneous rocks and recrystallized. They may perhaps in some cases have been mingled with these igneous masses by actual fusion. The whole complex has also been subjected to great dynamic movements. In this way has resulted a series of rocks whose original character cannot in all cases be deciphered, but which can be recognized as being of composite origin, the sedimentary portion representing extremely old if not the oldest sediments with which we are acquainted.

McGill University, Montreal.

SCIENTIFIC INTELLIGENCE.

I. CHEMISTRY AND PHYSICS.

1. Correction to the paper on Argon, Prout's Hypothesis and the Periodic Law; by EDWIN A. HILL. (Communicated.)The author of the above paper, published in the May number, desires to call attention to an unintentional omission for which he is responsible. On page 408, reference is made to "Lord Rayleigh's paper" and on p. 416 it is stated that "Lord Rayleigh has shown that at 13° C. water absorbs 4 per cent of its volume of argon, etc." In both cases no reference is made to the name of Professor Ramsay, who shared with Lord Rayleigh the joint authorship of the important papers referred to as well as the experimental work upon which they are based. This omission was unintentional and was indeed noticed before the paper was actually printed although too late to correct the proof. The scientific world appreciates so well the very important work of Professor Ramsay as co-laborer with Lord Rayleigh in this memorable research that this correction may seem to some unnecessary, but the author feels that it is due to himself that he should not fail to make it.

Two other corrections should also be made in the same article : In the note to page 414, 2d paragraph, for "silent discharge read "electric spark" and on page 408, line 15, for "force of gravitation" read "forces of attraction."

2. Porosity of solid bodies for the Light Ether.-ZEHNDER describes an interference apparatus by means of which he has endeavored to detect movements of the ether in connection with movements of surrounding bodies. The work was undertaken to test the following hypotheses of Fizeau, that either the ether adheres to the molecules of bodies and shares their movements; or that it is free and is not influenced by such movements; or that only a portion of the ether is free and that another portion is bound to the molecules of bodies and moves with them. Zehnder's apparatus consisted of an air-tight receptacle connected with long tubes through which light can be sent and suitably refracted and reflected in order to produce interference bands. By means of a moving piston the air in the tube can be set in motion and a change in the interference bands can be noted. Afterward the entire apparatus is exhausted of air and again the piston is moved in order to set the ether in movement. No change however could be observed in the latter case, and Zehnder remarks upon the limits of porosity of iron for the light ether. Michelson's experiments on the relative motion of the ether and the earth's atmosphere are commented upon and are repeated with similar negative results. The author concludes that the relative motion between the earth and the enveloping ether, at the observing station in Freiberg, did not attain the value of the

800th part of the velocity of the earth in its path.-Ann, der Physik und Chemie, 1895, No. 5, pp. 65-81.

J. T.

3. Wave length of the Ultra Violet lines of Aluminium.—C. RUNGE has made a determination of the strong line of aluminium in the ultra violet by means of a Rowland concave grating of a meter radius. The whole apparatus was placed in an air-tight apparatus from which the air could be exhausted, and for the observed lines the following values were obtained :

At 760mm and 20° C... 1854.09 1862.20 1935.29 1989.90 In vacuum. 1854:77 1862.81 1935.90 1990.57

1852.2

1860.2

1933.5 1988.1

According to Cornu The author calls attention to the discrepancy between his results and those of Cornu.-Ann. der Physik und Chemie, 1895, No. 5, pp. 44-48.

J. T.

4. Electrical Resonance.-V. BJERKNES has collected in a long and exhaustive paper the results of his experimental and mathematical study of the subject; and he shows that for quantitative measurements of electric waves great regard must be paid to the following five conditions: (1) The time of vibration of the oscillator. (2) The time of vibration of the resonator. (3) The logarithmic decrement of the oscillator. (4) The logarithmic decrement of the resonator. (5) The constant which measures the intensity of the vibrations. He shows that resonance phenomena are in general only suitable for quantitative measures when the mean value of the logarithmic decrement of the two conductors is smaller than 1. He indicates that quantitative measures with a spark micrometer are subject to error and that the electrometer method used by him is more suitable for the determination of the above five conditions. The student of Hertz effects will find this paper the best analysis of the conditions to be observed in performing experiments with Hertz apparatus which has appeared.-Ann. der Physik und Chemie, No. 5, 1895, pp. 121-169.

II. GEOLOGY AND MINERALOGY.

J. T.

1. Geological Survey of Michigan; LUCIUS L. HUBBARD, State Geologist. Vol. V, Part I. Upper Peninsula; Iron and Copper Regions. Part II. Lower Peninsula; Deep Borings. Lansing, Mich., 1895. The first part is a Geological Report on the Upper Peninsula of Michigan, exhibiting the progress of work from 1881 to 1884; Iron and Copper regions by C. ROMINGER, pp. 1-179, with a map and 2 geol. cross sections. Part II. The geology of Lower Michigan with reference to deep borings, edited from notes of C. E. Wright, late State Geologist, by ALFRED C. LANE, Assistant State Geologist, with an introduction on the origin of Salt, Gypsum and Petroleum by LUCIUS L. HUBBARD, pp. i-xxiv, 1-100 and plates i-lxxiii.-These reports refer to investigations which were made between the years 18811888 and in part have been referred to in Dr. Wadsworth's

annual reports to the Board published in 1892. The second report contains a careful compilation of the notes made by the late Mr. C. E. Wright, when state geologist, of the borings in various parts of the state; and the thickness and basin-like structure of the whole paleozoic series of southern Michigan, from the Trenton upward, is graphically shown in the sections. The following section and thicknesses are based chiefly upon borings at Jackson and Monroe. The names are those given to the formations by the authors.

These measurements show a considerably greater thickness than has been given in previous estimates by either Winchell or Rominger, especially in the Coal Measures and the Upper Silurian

strata.

H. S. W.

2. The Geological and Natural History Survey of Minnesota. N. H. WINCHELL, State Geologist.-The following three reports of this survey have recently been received, viz: The Geology of Minnesota, vol. iii, part I of final report. Paleontology, by Leo Lesquereaux, Anthony Woodward, Benjamin W. Thomas, Charles Schuchert, Edward O. Ulrich, Newton H. Winchell, pp. i-lxxv, 1-474, 41 plates and 34 figures, Minneapolis, 1895.

22d Annual Report for the year 1893, pp. 1-210, Minneapolis, 1895. 23d Annual Report for the year 1894, pp. 1-255, Minneapolis, 1895.

Part I of the Paleontology was communicated to the Secretary of State in 1891, and the several chapters of which it is composed have already appeared as separate brochures, and may have been examined already by many of our readers. The publication of these separate memoirs in this permanent form consti

tutes a valuable contribution to the detailed paleontology of the upper Mississippi valley area.

In the chapter on the Cretaceous Flora by Leo Lesquereaux, the author remarks upon the impossibility of explaining the sudden appearance in the Dakota fauna of the rich dicotyledonous flora by any gradual modification of the floras known from earlier epochs. "No species of the dicotyledonous series has as yet shown any such intermediate characters indicating by its inferiority a degree of transition: nor has there been found in the series of lower divisions of plants occurring below any whose characters would indicate a tendency to a transition to a higher order." The flora collected in this limited area from only three localities contains 28 species, only two of which are gymnosperms. And the dicotyledonous species are referable to 18 genera, and to the three great subdivisions of the dicotyledons; the Apetaleæ, the Gamopetalece and the Dialapetaleœ.

Cretaceous foraminifera are described by Messrs. WooDWARD and THOMAS, the sponges, graptolites and corals of the Lower Silurian by Messrs. N. H. WINCHELL and SCHUCHERT, and the larger part of the volume is devoted to "Descriptions of the Lower Silurian Bryozoa" by E. O. ULRICH, and the "Lower Silurian Brachiopoda" by Messrs. N. H. WINCHELL and CHAS. SCHUCHERT. The annual reports contain, among other papers, a critical examination of Dr. Williams' discussion of the greenstone schists of the Menominee and Marquette region of Michigan (Bull. U. S. G. S. No. 62), by N. H. WINCHELL, who defends his previously expressed opinion "that the great bulk of the 'greenstones' as an Archean terrane, ought to be classed as pyro-clastic, i. e., that they originated from eruptive agencies, as tuffs and all kinds of volcanic debris, sometimes very coarse and even distributed and somewhat stratified by the waters of the ocean into which the materials fell." A preliminary report on the Rainy Lake gold region is given by H. V. WINCHELL and U. S. GRANT. WARREN UPHAM gives in the latter report the evidence derived from the beaches of the various glacial lakes in the St. Lawrence basin; following a paper, in the previous report, in which occurs a detailed account of the glacial drift and morains of northeastern Minnesota.

H. S. W.

3. Doctorate Theses in Geology.-Two theses by Americans studying geology in European universities have been received,

viz:

Die Klippen region von Iberg (Sihthal), von Dr. EDMUND C. QUEREAU aus Aurora, Ill., 4 geol. charts, 4 profile plates and 13 zinkographs, pp. i-xi and 1-158, Bern, 1893.-This paper constitutes the 33d number of the Beiträge zur Geol. Karte der Schweiz.

Beiträge zur Kenntniss der Gattung Oxyrhina mit besonderer Berücksichtigung von Oxyrhina Mantelli Agassiz, (Palaeontographica, Bd. xli, pp. 149-191, Taf. xvi-xvii, Stuttgart, 1894) von CHAS. R. EASTMAN, Assistant an dem Museum Comparative Zoology, Cambridge, Mass.