For the American Railroad Journal and Mechanics Magazine. INTERNAL IMPROVEMENTS OF NEW YORK. NO. 2. Facts sufficient were adduced in the last number to demonstrate that the enlargement of the Erie canal to the size proposed is not required to accommodate any possible increase in the tonnage passing upon it for some years to come. It was there shown that the business on the western portion of the canal has thus far fallen far short of its capacity. It was also shown that the revenue from the whole canal had not, up to the date of the last report of the comptroller, been more than sufficient to defray the interest on its cost, together with the expense of repairs and superintendence. This being true of the whole canal, it requires no labored demonstration to show that its western portion is yet very deeply in debt to the State for its construction and maintenance, and in this respect is in the same predicament with the lateral canals. Upon the eastern portion, although at one period the business was nearly equal to the ability of the canal with single locks to accommodate, yet as the ratio of decrease in the products of the forest has far exceeded and is likely to exceed for some years that of the increase in the products of agriculture, there is no positive necessity for an enlargement, to accommodate the business that is likely to pass upon it. The correctness of this view of the subject is farther confirmed by the effect which the completion of the line of railway from the Hudson to the Lakes particularly that extending from Albany to Buffalo, will have upon the business of the canal. The distance from Albany to Buffalo by the canal is Difference in favor of railway, 363 miles 320 44 143 From Albany to Auburn 174 miles, and from Rochester to Batavia 30 miles, making in all 201 miles, the line of railway is completed, and in operation. Of the remaining 116 miles, 78 are under contract, and the remainder will ere long be constructed. The period is therefore, very near at hand, when there will exist a continuous line of railway from the Hudson to Lake Erie parallel with, and for most of the distance situated in the immediate vicinity of the Erie canal. The effect of the railway thus far has been to drive the packet boats from the canal and to give by the consequent diminution of lockages a relief to the canal fully equivalent to about 30 per cent. of the agricultural products, which, together with the rapid decline in the product of the forest, already explained, will place the period when the canal shall be doing business to the extent of its capacity, still more remote than was stated in my last number Previous to the construction of the railway the line boats, as they are termed, conveyed a great many passengers, and were provided with cabins for their accommodation. This branch of the business is becoming less profitable, and hence more boats in proportion are constructed after the plan of what are termed the lake boats, which are designed for the transportation of freight only. The effect of this change is to enable a less number of boats to convey a greater amount of tonnage, and thus diminish relatively the number of lockages. The locks being the only points where any obstruction exists upon the canal, a very great relief is reasonably anticipated from this cause. Much relief may also be expected from another source. The portion of the product of the forest which obstructs most the navigation, viz. the round and square timber which is conveyed in rafts or floats, is the portion which, in the great falling off in that branch of transportation, will probably most rapidly diminish. If in addition to this, a diminution be made in the tolls upon lumber, the rates being less at that season, viz. in midsummer, when the canal is the least crowded, the transportation of that article may be so regulated as to accommodate other articles requiring a more speedy transit, and at the same time add materially to the capacity of the canal. That there is a very considerable difference in the transportation upon the canal at different periods of the navigable season there is no doubt. It is certainly desirable to afford every facility for the expeditious conveyance of freight to market. But there is no doubt that by a proper arrangement of the tolls, sufficient inducements may be offered to those interested to alter the periods of transportation of particular articles in such a way as to greatly equalize the business of the canal. Without, however, any such arrangements, there is reason to believe that any extraordinary increase in pressure in the business will be relieved by the line of railway already described. It is true, indeed, that the legislature in the plenitude of its wisdom has prohibited the transportation of freight on a portion of the line of railroad from Albany to Buffalo, and on other portions exacts a tribute, equivalent to what the State would have received had the freight passed upon the canal. Assuming this policy to be based upon principles which are correct in the abstract, (which is far from being conceded,) there is no good reason why the restrictions may not be removed at those times, when the canal is incompetent to do the business that may be thrown upon it. Such an arrangement would afford great relief to the canal in times of pressure should such times ever occur, and if not found adequate, it is easy to show it to be for the interest of the State, and of all concerned, to give to the railroad companies whatever is necessary to induce them to undertake the transportation, rather than incur the enormous expense of the enlargement. The dimensions of the Erie canal as stated in the previous communication are 40 ft. width at surface and 4 ft. in depth. From information derived from those who navigate it, there are portions of it which do not exceed 3 to 3 ft. This is owing to the locks not having been excavated to the proper depth in the first instance, or to the subsequent accumulation of mud in the canal or perhaps to both causes combined. As to the fact of an insufficient depth at particular points there appears to be no doubt, and can only be attributed to unfaithfulness on the part of the original contractors, or to the remissness of the superintendents. This deficiency in the depth, is sufficient to make considerable difference in the capacity of the canal so long as there are portions, however limited in extent where the depth does not exceed 3 to 3 feet, the depth of draught and consequent load of the boats must correspond thereto, even if the remaining portions have a depth fully equal to or greater than the standard of four feet. For boats of the kind now used in navigating the Erie canal an increase in the load of about 16 tons produces an addition to the depth of draught of about six inches. By giving to the canal a uniform depth of water equal to what was contemplated viz. 4 feet, which may unquestionably be done without great expense, it is easy to perceive that its capacity for business will be much augmented. By this improvement alone the increase in its capacity may safely be estimated at 25 per cent. The capacity of a canal to accommodate the business of a country is limited when the speed of the boats and time of passing the locks are given : 1. By the depth of its channel. 2. The length and breadth of its lock chambers. 3. By the number of locks. The length of the lock chambers as already stated on the Erie Canal, is 90 feet. The boats average about 75 or 80 feet in length. By adding to the length of the chambers 15 or 20 feet, which might easily be done without disturbing the present walls or the foundation of the locks, the boats may be lengthened the same amount, and their tonnage increased in the same proportion, giving to the canal a capacity one fifth greater than it now possesses. Upon those portions also where the pressure of business is the greatest. additional locks, if required, could be constructed which when the improvement is made at all necessary points, would, with the other improvements mentioned above, give to the canal a capacity sufficient to accommodate two and a half to three times the amount of trade now conveyed upon it. These improvements could have been made gradually without interfering with the navigation and might have been embraced in the ordinary course of repairs, without necessarily increasing very much the annual expenditures for that object, and thus have left to the State a nett annual revenue to be applied to other objects of undoubted utility of more than half a million of dollars. As a farther evidence that the canal is not yet doing business to the extent of its capacity, it may be remarked that in prosecuting its enlargement thus far, most of the labor expended upon it has been directed to the erection of the mechanical structures-the materials for which, comprising timber and stone to a great amount, are in almost every instance transported for a greater or less distance on the canal. This great increase in the transportation, which of course is temporary, has caused no sensible inconvenience or obstruction to the navigation, and affords conclusive evidence that when the imperfections in the navigation above described and remedied the canal will afford abundant accommodation to the business for some time to come. The remarks thus far made in relation to the probable future business of the canal, have reference more particularly to the trade between the seaboard and the interior. There is another branch of business not the less important, which increases with the population and the development of the internal resources of the State. This is the internal trade of the canal consisting of the interchange of commodities between the several districts through which the canal passes. The canal, stretching as it does through a region of country of more than 300 miles in extent, the different portions of which are characterized by a great difference in soil and climate and in agricultural, mineral and manufacturing resources, there naturally exists an interchange of those productions of each, constituting an extensive internal traffic which will continue to increase. Making, however, all due allowances for the future increase in this branch of business and allowing also for the increase and decrease from the other sources and causes mentioned, we are forced to the conclusion that very many years will elapse particularly if the canal is improved as suggested, before it will be crowded with business to the extent of its capacity. So far, therefore, as the plea for the enlargement to the great dimensions proposed of 70 feet width and 7 feet depth, and the necessity of expending from 30 to 40 millions of dollars to effect it, is based upon the inadequacy of the canal to accommodate the anticipate dtrade upon it, it has no foundation in fact. How far this vast expenditure is warranted by the other reason which has been assigned in a reduction in the cost of transportation is a question which we shall endeavor to answer in the next number. FULTON. For the American Railroad Journal and Mechanics' Magazine. REMARKS ON THE ABSTRACT OF DR. LARDNERS PAPER ON RAILWAY 66 CONSTANTS, ETC.," PUBLISHED IN THE CIVIL ENGINEERS AND ARCHITECT'S JOURNAL FOR OCTOBER, 1839.-By W. R. Casey, Civil Engineer. Dr. Lardner has made a series of experiments to determine the amount of resistance offered to railway trains by the atmosphere, as well as the value of the "friction," the two resistances forming what has generally been called in this country, the "traction." His conclusions are precisely those of Mr. Wood, which Mr. Brunel considered impossible and against which he urged several objections which went to show the incorrectness of Mr. Wood s deductions as well as the little reliance to be placed in his experiiments, rather than to point out where the error lay. An attentive perusal of Dr. Lardner's paper led me to examine Mr. Wood's statements and Mr. Brunel's objections more closely, and, though Mr. Brunel failed to point out the grand source of error, it appears to me, that the late experiments of Dr. Lardner fully confirm the views of Mr. Brunel and other practical en gineers, and offer abundant proof of the utter fallacy of nearly all his own deductions as well as those of Mr. Wood. In all these papers the experiments are detailed with great minuteness, but the opinions of the writers. are given unaccompanied by the reasoning or calculations by which they ar. rived at these conclusions, so that to decide on their merits we are under the necessity of going through a formal investigation ourselves, instead of merely following them and judging of the accuracy of their mode of calculation. We will commence with the grand error of Dr. Lardner and Mr. Wood. The latter gentleman states in his Report: "The force exerted by 15 6-10ths tons down an inclination of 1 in 96 is equivalent to 364 pounds, and as this was the weight of the train in the first experiments, it follows that such a coach train moving at 31 miles an hour suffers a resistance of that amount, which includes both friction and atmospheric resistance. Again, the force exerted by 18 ton 1 cwt. down the same inclination is 421 12 pounds, and as the train having this weight moved with a uniform velocity of 32 1-4 miles an hour down the plane, this was its resistance at that speed.” Dr Lardner says: "The last experiment with a train of eight coaches, weighing nearly forty tons, shows that, in a dead calm, the resistance of that train at 31 miles an hour amounted to the eighty-ninth part of its weight; whereus the common estimate of the resistance of such a train at that speed has been hitherto about the 20th part of its weight! This fact alone, were it unconnected with any others, would sufficiently illustrate the enormous extent of error which has prevailed hitherto in such estimations in railway practice." Neglecting the difference between the length and base of the inclined plane under consideration as insignificant in its effects, nothing can be more true than, that the ratio of the length of the plane to its altitude represents strictly the ratio of the weight of a body on this plane to the force with which gravity urges or rather draws it down the plane. Consequently a body on a plane whose length is to its altitude as 89 to 1 will (omitting friction) be held in equilibrio with gravity on that plane by a force equal to the 1-89 o its weight-in other words, the force down the plane is equal to the resistance, and both are equal to 1-89 of the weight of the body left free to the force which gravity is able to exert on an inclination of 1-89. Now, what is the result of gravity in the experiment just quoted from Dr. Lardner's paper? The force of gravity on an inclined plane of 1-89 or, which is the same thing, the 1-89th part of the weight of the 8 coaches (40.75 tons) generates and keeps up a velocity of 31-4 miles per hour, overcomes the friction and the resistance of the atmosphere. Dr Lardner and Mr. Wood consider the entire force of gravity to be expended in counteracting the two latter resistances, and entirely overlook that portion of the force or of the height of the plane which generates and keeps up the velocity. Suppose at the foot of the plane of 1-89 another plane inclined in the opposite direction, then the train of coaches descending with a velocity. of 31-4 miles per hour would ascend this second plane till the momentum derived from the first plane was destroyed by the counteracting force of gravity on the second, and it is the difference between the height of the starting and stopping points on these two planes, not the absolute height of the first nor yet its angle of inclination, which expresses the resistances from friction and from the air. It will readily be observed, that this rea |