feet. Between Coeyman's and New Baltimore the channel is crooked, and near the foot of Mull's island it divides into two branches, with a middle ground between, which unite again above New Baltimore. Schodac creek is navigable for sloops at all times as high up as the village of Schodac. It unites with the main stream through the branch called the Hellegat. Sohodac creek-commencing our view at the head of the Hellegat, the depth of water in the channel is not less than 6 feet, and increases from that to 9 feet; at the foot of Schodac island it is 84 feet, and off Schodac dock it is 9 feet; and the water is not less than the last mentioned depth to the foot of lower Schodac island, with occasional increases of 12 and 13 feet. It continues nearly with an uniform depth to the lower end of Houghtailing's island, and, at that point, the channel would require to be widened. The improvement of the bed of this creek is a matter of no great importance, nor is it included in the estimate. During high water, steamboats sometimes pass through it to avoid the currents in the main branch. 8. The islands are large, and, by their position, contract the width of the stream. 10. The improvements proposed are to straighten the channels at one or two points, to erect guide lights at the separation of the channel below the foot of Mull's island, and to protect the side of the last island. The whole length of the survey as measured on the bank of the stream is 25 miles and 498 feet. The average width of the river between the banks on the first sheet is 1,046 feet, on the second 960 feet, on the third 1,450 feet, on the fourth 1,689 feet, on the fifth 1,934 feet, on the sixth 2,250 feet, on the seventh 4,030 feet; and gives an average width of the whole length of the stream 1,893 feet, or 631 yards. The space occupied by the rivers and islands amounts to 5,757 acres, and that alone by the islands is 3,516 acres, or leaving 2,241 acres for the area of the main channel, and the different branches. Tides.-The quantity of water running from the upper parts of the stream in the tide channels, constantly fluctuates, and occasions more or less variation in the rise and fall of the tideal waters. In the spring and fall, the tides are the least sensible, but as the river shrinks, and the supply from above diminishes, the tides rise and fall more uniformly. The following facts, ascertained from observation, will give us some light on this intricate subject. Å tide register was kept at Troy from 31st May to the 11th of June, 1831. The wind in that period blew principally from the south. The state of the tide was noted hourly from 7 o'clock A. M., to 7 o'clock P. M., making 12 hours daily The greatest rise in any one day was 26 inches, and the greatest fall 19 inches; and the most rise in an hour was 5 inches, and the most fall 7 inches. A tide register was kept at Albany from the 27th of May, to the 16th of July, 1831. The condition of the river was noted hourly from 8 o'clock A. M., to 6 o'clock P. M., which continued to the 14th of June. It was then changed to 7 A. M. and 6 P. M. The greatest rise during the above time was 32 inches; and the most fall 37 inches, and the rise in an hour with a strong southerly wind was 9 inches, and the fall in an hour, with a moderate northeast wind, 8 inches. A tide register was kept at Castleton from the 20th of June to the 7th of July. The rise and fall of the tide was noted hourly from 7 o'clock A. M. to 6 o'clock P. M. The winds were very variable, and there was eon most fall 37 inches. The greatest rise in an hour 11 inches, and the greatest fall 7 inches. A tide register was kept at New Baltimore from the 9th to the 16th of July, 1831. The hours of observation the same as at Castleton. The highest tide 48 inches, and the lowest 51 inches. The greatest rise in an hour was 15 inches, and the most fall 10 inches. It therefore appears that the highest and lowest water was Place. At Troy Castleton New Baltimore Highest water. Lowest water. From the registers we collect the following facts:-1st. That the tides run out longer than they run up. 2d. That the tides fall with greater rapidity than they rise. 3d. That the velocity of the ascending tides are increased by southerly winds. 4th. That when southerly winds prevail strongly, that the river does not fall so low as it rises, unless it is in the state of flood. 5th. When northerly winds prevail, the tides fall lower than they rise. 6th. When the river is in the state of high flood, the tides do not act, although the river swells and falls, occasioned by the flood waters being obstructed by meeting the ascending tides. The common difference in time between the rise and fall of the tide waters at Albany and Troy varies from one to one and a half hours. By the tide registers it appears that, in some instances, while the river was actually swelling at Troy, it had commenced falling at Albany. This is to be attributed to accidental floods and winds, and the curve in the river at the head of Breaker's and Hillhouse islands. At Albany, the tides are from to 14 hours longer in falling than at Castleton, and the difference in time between the tides at the first place and New Baltimore, is from 14 to 2 hours; accompanied by the same general phenomenon I have remarked in speaking of Troy. From the facts I have mentioned, it became necessary to establish the lowest water in the stream, that further observations should be made. Fixed points were therefore left at the places the registers were kept, and the distances measured from them to the lowest tide which occurred during the survey. Mr. Hagner was instructed to revisit those places when the river subsided to its lowest condition, and compare the two measurements. From his observations, it appears that the river had subsided at the Waterford bridge, since the survey, two feet; at the upper end of the sloop lock one foot nine inches; immediately at the foot of the sloop lock two feet nine inches; at Troy one foot ten inches; at Albany two inches; at Castleton eleven inches; and at New Baltimore one inch. Winds.-The prevailing winds at Albany, according to the meteorologieal table kept by professor Beek, was, in 1828 and 1830, as follows: Course of winds, Years. Days. Years. Days. From this table, it appears that the winds prevail from the south for a longer period than from any other quarter; and, in 1828, it ranged, from S. E., south, and southwest 192 days; and from the same direction in 1830, 167 days; and for the same periods, from northeast, north, and northwest, 121 and 146 days. Currents.-The bends, the banks, and bed and slope of the stream have a powerful influence on the speed and force of its currents, and on their local situations. They therefore properly come under three classes. are rivers situated above tide waters in which the current is uniformly in one direction. The second is of a mixed character, combining a rush of water in floods, and the ebbing and flowing of tides. The third and last are streams in which the rise and fall of the tides are nearly uniform. Many rivers, however, combine all these classes, and such in fact does the Hudson. Above the city of Troy, the first class is applicable; the second as low down as the city of Hudson, and in high floods to the village of Poughkeepsie; and the third from that point passing by the city of New York to the ocean. If we suppose the river between the city of New York and Troy had an uniform width, course and depth, and that its supply above the last point was cut off, the ebbing and flowing and heights of the tides between the extreme places would be governed by the distance from the ocean, which would occasion so small a variation of height in theory, that it would produce little or no alteration in the planes of high and low water. But if the stream should become gradually more crooked, shallow and narrow, and its channels obstructed by islands and shoals, the ascending tide having to overcome the friction on the bottom and the sides of the stream, and other obstructions, the velocity would be proportioned to the obstructions encountered, and the pressure of the ascending waters, and if these obstructions were met at the same points by the up and down tides, the currents at those places would always, at certain hours in the day, be equal. But frequently what would be a positive impediment to the ascending current, would offer no obstruction to the descending one. The local character of the stream has therefore more influence in these matters than is generally admitted. The ascending and descending currents are therefore accelerated or retarded in their progress. If we imagine a curve in the river, the force of currents being equal on both sides, a bar would be formed at the vertex of the bend. But, in either of the two first classes of streams, this bar would form on the lower side of the bend, and not at the vertex. And at expanded widths where the currents were diminished in velocity, bars, shoals and shallows would accumulate. But, at the mouth of the stream, owing to the action of winds and waves, bars would be formed. In the class first examined, the stream was considered as being within the entire scope of tide waters. I shall now take the second or mixed class. The velocity of the ascending tides is checked by the quantity of water flowing into the tide channel, or its speed is impeded in proportion to the intensity of the impact of the waters; for the particles of all fluids are considered by writers as globular or spherical bodies; but if we remove the ascending pressure, the current would be equally accelerated by the flow of water from the upper parts of the river, as the ascending tide was retarded by it. It is therefore apparent that the force of the down current would be greater, and that it would continue longer to run out, than the tide upwards. channel is filled with flood water; in this case, the ascending tides owing to the greater intensity of the pressure from above, are held back until an equilibrium between the currents ensues, and the flood waters from that point become inactive, until the tides begin to run out; it then sweeps down with greater force than before, until its power is lost in the increased depth and width of the stream. The flood water being held back by the ascending tide, and its velocity checked, it will occasion an accumulation or swelling of water which falls again to the flood height on the pressure being removed. This variation is by some writers erroneously attributed to the tide waters passing under the flood, and raising it up. At the meeting of the flood and tide waters, bars would be formed. But the bottom and the sides of the stream are more corroded by the down than the up current, and the former is never less than at extreme low water, while the latter constantly fluctuates. The deposites in the stream would therefore be constantly on the move down, and there would be no danger of the ascending tides forcing them back. But it may be asked, why do bars and shoals form at various points? This is owing to the deposites carried down in floods, and left by local obstructions at the head of islands, at bends, at increased widths of the river where the currents are diminished, and by other causes. We have, therefore, the following facts relating to the section of river to be improved: 1st. That all heavy materials are deposited in the upper parts of the stream, and the lighter lower down; for all the bars above Albany are gravel and other heavy soils, while all below Albany are sand and other lighter deposites. 2d. That the dam between Troy and Waterford has, in some degree, prevented the rapid deposites which, in former years, were making in the stream. 3d. That the current is, in all cases, stronger down than upwards, unless the river is very low, and strong southerly winds prevail. 4th. That the obstructions are occasioned by local causes, which are to be removed by artificial works, and by other means. Rivers. Fluids, unless agitated by winds or other causes, gravitate in proprio loco. It therefore follows, that the surface of stagnant fluids are segments of a sphere, as they all gravitate towards the centre of the earth; but these particles yield to any force impressed, or they will remain at rest until put in motion by some foreign power, such as winds, floods, tides, or the sudden emission of an increased quantity of fluid matter, to produce motion or velocity, which is again increased by the slope over which it rolls, or the height from which it falls. When it therefore moves uniformly, the resistance is equal to the accelerating force, and the difference between its bottom and top velocities are proportional to the square root of the superficial velocity. But, without entering into further remarks, I will assume facts which have been established by observation and experience. 1st. The extent of deposites in all streams depend on the soils through which they pass, and on the character of their tributary branches.. 2d. As the force of the currents vary, so does also the quantity and extent of deposites. 3d. Deposites always occur where there is the least velocity. 4th. Streams raise their beds at some points, and lower them at others. 5th. Shoals form where the river has the greatest width, and at bends, and where it is the narrowest, it is the deepest. 6th. Bars are formed by counter currents, or by eddies, or by the direction of the current being suddenly changed from its course by foreign obstructions. 7th. All streams are higher at the upper than at the lower side of a bend; a cut through such point would therefore accelerate the velocity of the stream. 8th. The tendency of all streams is to raise their banks and islands, by overflowing them in the spring and autumn, and depositing the soils which they hold in solution on them. 9th. The waters of all streams contain more or less foreign matter, and their deposites, though small, are going on perpetually. The stream contains the least quantity when at its lowest condition, and the greatest when it is the most swollen. 10th. The heaviest soils are deposited in the upper parts, the lighter in the lower sections of the stream. 11th. The greatest slopes of all streams are near their sources, and they diminish in fall as they approach the ocean. 12th. Ice is a powerful agent in effecting changes in the beds of streams. Its force and strength depend on its thickness, and the momentum of cur rents. To collect such useful information relating to the navigation of the stream as could with confidence be relied on, I addressed several communications to different gentlemen, containing queries, and soliciting their replies; and it is with great pleasure I return my sincere thanks to them for their promptness in furnishing me with the results of their observations and experience. The first reply to the queries is from William James, esquire, of Albany, Chairman of the Chamber of Commerce, after a joint consultation with the Mayor of the city, and other individuals. The next, from Townsend M'Coun, esq. of Troy, one of the commissioners appointed by the Legislature of the State of New York, in 1819, to ascertain the best mode for the improvement of the navigation of the Hudson. river. Query 1st. The length, breadth, draught, and tonnage of vessels employed in the trade of the river? Reply of Mr. James. "The average length of the Albany sloops is 75 feet, breadth 25 feet, draught of water when loaded 9 feet, and they average 125 tons: vessels come here, and several belong to the city, which exceed these dimensions in every particular." Reply of Mr. M'Coun. "Sloops from 50 to 55 feet keel, and from 20 to 25 feet beam, drawing from 6 to 8 feet water, loaded from 70 to 120 tons. Scows, decked, 60 to 80 feet long on deck, 18 to 23 feet wide, carry from 80 to 150 tons. Tow-boats carry from 150 to 300 tons, draught from 6 to 8 feet." Query 2d. The depth of water required by the interest, and the amount of trade at extreme low water? Reply of Mr. James. "A depth of 8 feet water is necessary at the lowest tides; a depth of 8 feet water will be a great relief from the present difficulties, but if it be increased to 10 feet, it would directly create a West India and whaling trade, and other foreign enterprise, which, of course, would add to the prosperity of the city, and increase the shipping and |