times the water-level varied rapidly in the harbour, while no such variations occurred in the barometer at the place of observation."

As a general rule, these variations in the water-level indicate the approach of a storm, or a disturbed state of the atmosphere. The barometer is not sufficiently sensitive to indicate the sudden elevations and depressions, recurring, as they often do, at intervals of ten or twelve minutes; and the result of observations at such time may, in some degree, be regarded as negative. Besides, it may not unfrequently happen, that, while effects are witnessed at the place of observation, the cause which produced them may be so far removed as not to influence the barometer. We are, therefore, led to infer that these phenomena result, not from the prevalence of the winds acting on the water, accumulating it at one point and depressing it at others, but from sudden and local changes in the pressure of the atmosphere, giving rise to a series of barometric waves. The water, conforming to the laws which govern two fluids thus relatively situated, would accumulate where the pressure was the least, and be displaced where it was the greatest. It has been remarked by De la Beche, that a sudden impulse given to the particles of water, either by a suddenly increased or diminished pressure, would cause a perpendicular rise or fall, in the manner of a wave, beyond the height or depth strictly due to the mere weight itself. The difference in the specific gravity of the water of the lakes and the ocean may cause these changes to be more marked in the former than in the latter.— American Annual of Scientific Discovery, p. 245.

4. Water Thermometer.-Lieut. Maury states that he has been very much assisted in developing his theory of winds and currents by means of the thermometer used by some vessels for determining the temperature of the water. It was by means of these observations on the temperature of the water that he was enabled to prove that, off the shores of South America, between the parallels of 35° and 40° south, there is a region of the ocean in which the temperature is as high as that of our own Gulf stream, while in the middle of the ocean, and between the same parallels, the temperature of the water is not so great by 22°. Now, this very region is noted for its gales, being the most stormy that the as yet incomplete charts of the South Atlantic indicate. Lieut. Maury says, however, that very few navigators make use of the water thermometer, so that he has experienced some inconvenience in his undertaking. He is the more surprised at this, from the fact that New York owes much of her commercial importance to a discovery that was made by this thermometer. At the time when Dr Franklin discovered the Gulf Stream, Charleston had more foreign trade than New York and all the New England States together. Charleston was then the halfway house between New and Old England. When a vessel, in attempting to enter the Delaware or Sandy Hook, met a north-west gale or snow storm, as at certain seasons she is apt to do, instead of

running off for a few hours into the Gulf Stream to thaw and get warm, as she now does, she used to put off for Charleston or the West Indies, and there remained till the return of spring before making another attempt. A beautiful instance this of the importance and bearings of a single fact, elicited by science from the works of nature.Annual of Scientific Discovery, p. 160.

5. On the Falls of Niagara.-If we follow the chasm cut by the Niagara river, down to Lake Ontario, we have a succession of strata coming to the surface of various character and formation. These strata dip south-west or towards the Falls, so that, in their progress to their present position, the Falls have had a bed of very various consistency. Some of these strata, as the shales and medina sandstone, are very soft, and, when they formed the edge of the Fall, it probably had the character of rapids; but, wherever it comes to an edge of hard rock, with softer rock-beds below, the softer beds, crumbling away, leave a shelf projecting above, and then the fall is perpendicular. Such is the case at present; the hard Niagara limestone overhangs in tables the soft shales underneath, which at last are worn away to such an extent as to undermine the superincumbent rocks. Such was also the case at Queenston, where the Clinton group formed the edge, with the medina sandstone below. This process has continued from the time when the Niagara fell directly into Lake Ontario to the present time, and will continue so long as there are soft beds underneath hard ones; but, from the inclination of the strata, this will not always be the case. A time will come when the rock below will also be hard. Then, probably, the Falls will be nearly stationary, and may lose much of their beauty from the wearing away of the edge rendering it an inclined plane. I do not think the waters of Lake Erie will ever fall into Lake Ontario without any intermediate cascade. The Niagara shales are so extensive that possibly, at some future time, the river below the cascade may be enlarged into a lake, and thus the force of the falling water diminished; but the whole process is so slow, that no accurate calculations can be made. The Falls were probably larger, and stationary for a longer time at the "Whirlpool" than anywhere else. At that point there was no division of the cataract, but at the "Devil's Hole" there are indications of a lateral fall, probably similar to what is now called the American Fall. At the Whirlpool, the rocks are still united beneath the water, shewing that they were once continuous above its surface also.*-Agassiz on Lake Superior, p. 15.

6. On the Existence of Manganese in Water.-At a meeting of the American Academy, in January 1849, Dr Charles T. Jackson

* The data on which these and the previous remarks on the geology of the Falls are founded, are derived from Professor James Hall's investigations in the New York State Survey. A.

stated that he had discovered the presence of manganese in the water of streams, lakes, &c., almost universally. He detected it in water from the middle of Lake Superior, in Cochituate water, and in water from various sources. It has usually been regarded as iron in previous analyses. He considered the observation as having an important bearing in accounting for the deposits of bog manganese at the outlets of ponds, lakes, and in bogs, as well as for the source of the oxide of manganese in the blood.Annual of Scientific Discovery, p. 202.

On the Presence of Organic Matter in Water.-The following facts relative to the presence of organic matter in water were presented to the British Association, by Professor Forchhammer, as the result of extended observations on the water, near Copenhagen.

mer.

1st, The quantity of organic matter in water is greatest in sum2d, It disappears, for the most part, as soon as the water freezes. 3d, Its quantity is diminished by rain. 4th, Its quantity is diminished if the water has to run a long way in open channels. The hypermanganate of potash or soda is recommended by the Professor as a most excellent test for the presence of organic matter in

water.

7. Arsenic in Chalybeate Springs. Since the discovery of arsenic in the deposits from certain chalybeate springs, it has been asked whether the poisonous properties of this substance are not neutralized by the state in which it is found. M. Lassaigne has finished a series of experiments connected with this subject, for the purpose of ascertaining the proportion of arsenic contained, in what state of combination it exists, and the nature of the action which these arseniferous deposits exert in the animal economy. The following are M. Lassaigne's conclusions:-1. In the natural deposits of the mineral waters of Wattviller, arsenic exists to the amount of 2.8 per cent. 2. A portion of these deposits, representing 1.76 grains of arsenic acid, or 1·14 grains of arsenic, produced no effect upon the health of a dog. 3. This non-action shews that the poisonous property of the arsenic is destroyed by its combination with the peroxide of iron, and thus confirms what has been before asserted, that peroxide of iron, by combining with arsenuous and arsenic acid, destroys their poisonous properties, and consequently becomes an antidote for them.

GEOLOGY.

8. The Coal Formation of America.-The coal regions of America are, from the explorations which have thus far been made, supposed to be divided into three principal masses; the great central tract, extending from Tuscaloosa, Alabama, to the west of Pennsylvania, and being apparently continued to New Brunswick and Novia Scotia ; the second tract strikes north-westward from Kentucky, crosses the Ohio, and stretches through Illinois to the Mississippi River; a third

region, smaller than the others, lies between the three great lakes— Erie, Huron, and Michigan. Competent geologists affirm that, fro a comparison of the coal strata of contiguous basins, these are no more than detached parts of a once continuous deposit.

The extent of this enormous coal-field is, in length, from northeast to south-west, more than 720 miles, and its greatest breadth about 180 miles; its area, upon a moderate calculation, amounts to 63,000 square miles! In addition to these, there are several detached tracts of anthracite in Eastern Pennsylvania, which form scme of the most remarkable coal tracts in the world. They occupy an area of about 200 square miles.

The strata which constitute this vast deposit comprehend nearly all the known varieties of coal, from the dryest and most compact anthracite to the most fusible and combustible common coal. One of the most remarkable features of these coal-seams is their prodigious bulk. The great bed of Pittsburg, extending nearly the entire length of the Monongahela River, has been traced through a great elliptic area, of nearly 225 miles in its longest diameter, and of the maximum breadth of about 100 miles, the superficial extent

14,000 square miles, the thickness of the bed diminishing gradually from 12 or 14 feet to 2 feet. In 1847 the anthracite coal region of Pennsylvania furnished 3,000,000 tons, and 11,439 vessels cleared from Philadelphia in that year, loaded with the article. The produce in 1848 and the present year, is of course larger.

The bituminous coal area of the United States is 133,132 square miles, or one 17th part of the whole. The bituminous coal area of British America is 18,000 square miles, or one 45th part; Great Britain, 8139 square miles; Spain, 3408 square miles, or one 52d part; France, 1719 square miles, or one 118th part; and Belgium, 518 square miles, or one 122d part. The area of the anthracite coal formations is down at 437 put square miles of Great Britain and Ireland anthracite and culm, at 3720 square miles. The anthracite coal of Great Britain and Ireland,

and that

of

is not nearly so valuable an article of fuel as the anthracite coal Pennsylvania, nor does a given area yield so much as the latter.New York Express. American Annual of Scientific Discovery, p. 271.

He

8. River Terraces of the Connecticut Valley.-At the meeting of the American Association in August, President Hitchcock of Amherst College, read a paper "On the River Terraces of the Connecticut Valley, and on the Erosions of the Earth's Surface." stated that his paper must be considered as containing a few facts and suggestions and not a finished theory. He has examined the valley from its mouth to Turner's Falls, and carefully measured the heights of the terraces. "As you approach the river you find plains of sand, gravel, or loam, terminated by a slope sometimes as steep as 35°, and a second plain, then another slope and another plain,

I find that these terraces

and so on, sometimes to a great number. occur in successive basins, formed by the approaches of the mountains upon the banks at intervals. Sometimes the basin will be 15 or 20 miles in width, but usually much narrower; and it is upon the margins of these basins that the terraces are formed. I have rarely found terraces more than 200 feet above the river, which would be in Massachusetts, about 300 feet above the ocean, and at Hanover, N.U., about 560 feet. Nowhere do they exist along any river, unless that river has basins. As to the materials of which they are formed they appear exceedingly artificial. The outer or highest terrace is generally composed of coarser materials than the inner ones. They are all composed of materials which are worn from the rocks, but the outer terrace oftener is full of pebbles, some of them as large as 12 inches, while the materials of the inner seem reduced to an impalpable powder, like the soil of a meadow which is overflowed during high water. Whence did these materials originate? The materials were first worn from solid rocks, and afterwards brought into these valleys. The outer terrace appears to have been often in part the result of the drift agency. Afterwards, the river agency sorted the materials, and gave them a level surface, the successive basins having at that time barriers. The inner terrace appears to have been, at least in its upper part, the result of deposition from the river itself.

"I will now mention a few facts which I have observed. The terraces do not generally agree in height upon the opposite sides of the valley. The higher ones oftener agree, perhaps, than the lower ones. If formed, as I suppose, from the rivers, we should expect this. The terraces slope downwards in the direction of the stream. The same terrace which, near South Hadley, is 190 feet above the river, slopes until, at East Hartford, it is only 40 feet above the river, thus sloping 150 feet more than the slope of the river itself, in a distance of 40 or 50 miles. This shows that they could not have been formed by the sea or by a lake, for they would then have been horizontal. The greatest number of terraces observed is eight or nine. Generally there are but two or three." President Hitchcock then gives his view of the precise mode in which these terraces were formed, illustrating them by references to other parts of our country, and concludes by a notice of the erosions of the earth's surface.-Annual of Scientific Discovery, 1850, p. 229.

ZOOLOGY.

10. Fossil Crinoids of the United States. —At the meeting of the American Association, 1849, a paper on the fossil crinoids of Tennessee, by Professor Troost, was read by Professor Agassiz. The

*

*These fossiliferous remains were discovered in the carbonaceous and silurian strata of the State, and shew a wonderful development of that form of aniVOL. XLIX. NO. XCVII.-JULY 1850. M