moistens the surface exposed, as to prevent ignition from the sparks; indeed, so rapidly does the steam condense during very cold weather in winter, that the water falls in drops from the interior of the bridge roof. Coals have sometimes fallen from the ash-pan of the engine on the floor of the bridge; any danger, however, from this source, is obviated by a slight coating of gravel distributed over the exposed surface. Confidence, it is believed, may therefore be justly entertained, that so great a calamity as the destruction of one of these viaducts by fire need not be apprehended from the use of locomotive engines upon the road; yet it is by all means important that a watchful eye should continually be kept over them. The inclined planes are, and have continued during the past season, in excellent condition. I am happy to state, that in the ordinary operation of ascending and descending the plane with the aid of the machinery, not single accident of a serious nature has occurred during the past year. The operation of the planes is, however, always attended with more or less delay, particularly in damp weather when the adhesion of the rope is liminished, and the detensions which occur are exceedingly annoying to travellers, the fault-finding part of whom, without stopping to inquire the cause, do not hesitate loudly to attribute it to the mismanagement of the public agents. So much has been said about the construction of railways to avoid the Schuylkill and Columbia inclined planes, that I was last summer induced to make a cursory examination, with a view to ascertain the fall and distance from a point on the railway near the Spread Eagle crossing, in Radnor township, by way of the Gulf Valley to the Schuylkill, thence along the Schuylkill to the west end of the viaduct at the foot of the inclined plane. This distance is found to be fifteen and one quarter miles, (about two miles further than by the present railway,) and the fall three hundred and eighty-one feet, being at the rate of twenty-five feet per mile. I did not, however, trace the line over the ground upon which the railway would be located, neither did my limited time allow me to take any notes with a view to estimate the cost of a railway upon that route; but, from general observation, I am of opinion that the undulating character of a large portion of the line would render the grading of a railway upon it decidedly expensive; it is, however, by no means impracticable, and is certainly wor thy of a more minute examination. At the request of the citizens of Columbia, I have also made an examination, with plans. estimates, &c., of a line of railway to avoid the Columbia inclined plane; this line commences near the village of Mount Pleasant, and, passing down the valley of Strickler's run, crosses the present railway near the foot of the inclined plane, at an elevation of about twenty feet above the track, and enters Front street, in which it was designed to be continued to the basin; the whole distance of five and one quarter miles being not more than one-third of a mile longer than the present line, and the graduation will not exceed thirty-four and a half feet per mile. The grade, however, can be reduced to thirty-three and one-third feet per mile, and a superior line be obtained, by keeping to the east of Front street after crossing the railway, and passing through what has been commonly termed the alley route, which will intersect the present railway on the east side of the basin, thereby affording additional facilities for the transaction of business. The grade, although higher than desirable, yet being within the limits of locomotive power, is deemed so much superior to the present arrangement, as to justify the opinion that the charge is well worthy being recommended to the serious consideration of the legisla ture. The estimated cost of this change, if the rails are removed from the present line, is $110,000; or, if laid with a new wooden track, $133,360. Motive Power. At the date of my last annual report, two locomotive engines, viz: the Lancaster and Columbia, were in successful operation upon the line, and thirteen others had been contracted for, the most of which were expected on the road early in the spring. This anticipation, however, was not realized, as but seven engines were in readiness to meet the demands of the spring trade, since which time the number has gradually increased to seventeen, viz: ten manufactured by M. W. Baldwin, Esq.; five by Robert Stevenson of England; one by Coleman Sellers & Sons; and one by Long & Norris, the latter two have been but recently put upon the road, and their capacity is not yet fairly tested; they are, however, believed to be excellent engines. The engines from Mr. Baldwin have all been tested, and found to be of the first class. The five engines imported from England, are not so efficient as those manufactured in this country; the workmanship of them is good, but many important parts of the machines are too light to enable them to encounter (with a heavy load) the higher grades and severe curves on this railway; in consequence of which, frequent repairs are required upon them. These engines were not obtained from England, (as has been gen erally supposed,) with the view of getting better engines than could be procured in this country, but simply because locomotives could not be manu. factured here, fast enough to meet the wants of the road. My own opinior has always been in favour of encouraging the mechanics of our country in the manufacture of engines. Nothing but a suitable degree of encouragement is wanting to arouse the native enterprise of our mechanics to this important branch of business; and locomotive engines brought from England to this country for sale, will most assuredly find a bad market. There are not at present a sufficient number of engines on the road to meet the current demands of the trade, as in consequence of repairs required, not more than two thirds of the number on the road can be kept in readiness for actual service. This deficiency will, however, be in a great measure diminished, whenever duplicates can be obtained for such parts of the engines as are most liable to injury, and workshops can be properly arranged to do the repairs without the loss of time. Indeed, the want of suitable workshops, during the past season, to do the repairs promptly, has materially lessened the amount of available power on the road. It may be asked, "Why these workshops were not built"? To this I can only reply, that it was last year contemplated to erect additions to the shop at Columbia, so as to do all the repairs at that end of the road; but before funds were provided for the prosecution of the plans proposed, the rapidly increasing trade on the road suggested the propriety of selecting a more central position on the line for their location. It was therefore, thought most prudent to defer the matter for a month or two, that the proper point might be more clearly indicated, by the running of the engines. After due consideration of all the advantages and disadvantages, which seemed to have a bearing on the subject, it was early in July decided to erect the workshops, necessary to do all the repairs upon the road, at Parkesburg, being the point selected for the junction of the Oxford railway and the state works. This position embraces many advantages: such as being very nearly central; it is healthy, and has an excellent spring of running water for the supply of the engines. It may be proper here to remark, that a donation of all the ground required for the accommodation of the workshops, together with a lot for a collector's office, has been made to the commonwealth, by the owner, Mr. Parke. The depot and workshops are now finished, and in readiness for the reception of the tools, and machinery, which are in a state of preparation, and will probably be completed during the present month. It is to be regretted that the want of funds has not allowed the erection of the necessary dwellings, for the workmen connected with the shops, as boarding is difficult to be obtained in the vicinity, which will of course interfere with any system that may be adopted for the repairs, until an ap propriation shall be made for the necessary buildings. When this is done, and the buildings completed, a proper degree of economy can be preserved in this important branch of the establishment. The engines upon this road have generally performed their trips with great regularity; and it affords me pleasure to add, that the American engines, delivered within the present year, are capable of doing more work than was estimated in my last report: the most of them, in their ordinary trips, draw a gross load of seventy-five tons. The engine Schuylkill has drawn over the road a gross load of one hundred tons, and several others have drawn, over the highest grade, from eighty to ninety tons gross. When the curves and grades upon this road are taken into consideration, it is believed that the performance of these engines will be found equal to any in America. It is also gratifying for me to be able to state, that most of the prejudice which existed along the line against the use of locomotive engines last year, appears to have vanished, and in its place has arisen a prepossession in their favor: this however, is nothing more than might reasonably have been expected, for certainly no intelligent individual can witness the performance of a single engine, drawing a train of fifteen cars, loaded with three tons each, from one inclined plane to another, (seventy-seven miles,) in eight hours, without honestly acknowledging the decided superiority of steam over horses at least so far as its application to railways. Of the twenty locomotives authorized to be obtained for this railway, seventeen (as has been previously stated) are upon the road, and the remaining three will probably be put on during the present month. The cost of twenty engines, complete, will be $126,000 6,500 As no separate account was kept, by the collectors, of the motive power received prior to the first of January last, and as all the expenses of that branch of the establishment were paid out of the construction fund up to the 1st of February, I am not able to furnish a comparison of the receipts and expenditures for motive power, previous to the latter date. The following statement will, therefore, exhibit its income and cost for nine months, commencing February 1st, and ending November 1st. Amount received by collectors for motive power, Expenditures and debt, (see supervisor's report,) Excess of receipts over expenses, to this is added the excess of stock on hand over last year, The actual excess over cost will stand, Or, if from the expenditures, Be deducted stock on hand over last year, $ 46,514 98 45,431 75 The actual cost for motive power, for nine months, will stand, $40,976 45 Or, average cost per day, 150 00 It is believed, that the receipts and expenditures of the ensuing year will be at least double the amount of the last year; but, as with the present tolls they would probably progress in nearly the same ratios, the preceding result will afford safe data to estimate the value of the motive power to the commonwealth. Taking, therefore, ten engines as the average number upon the road during the past season, the cost of which, at six thousand three hundred dollars each, would be sixty-three thousand dollars— Interest of which is Deduct above interest from surplus receipts and stock on hand, Balance left towards refunding the principal, $ 3,150 00 5,538 53 $ 2,388 53 This, it is evident, will not be sufficient, as the durability of an engine will probably not exceed four, or, at furthest, five years, which would render an amount of fourteen thousand dollars per annum necessary to replace the engines, or about eleven thousand six hundred dollars more than the surplus of the present year, to each ten engines. It is believed, however, that a large portion of this amount would have been received during the past year, if all the tolls from passengers traveling on the road had been collected; but as this evidently had not been done, in order to remedy the evil, I would recommend that a careful and attentive agent of the commonwealth should be placed on each line of passenger cars, whose duty it shall be to keep a way-bill, in which he shall note the number of passengers in each car, and the distance traveled by them-and who shall also see that the conductors of each car, or train of cars, keep a like way-bill, upon which the names of all the passengers should be entered.-This plan, it is believed, would soon ensure an important increase to the revenues of the commonwealth. In order, however, to aid still further in obtaining a surplus fund for the renewal of the engines, I would suggest the propriety of increasing the toll, for motive power, on each passenger, to one cent per mile. This change would probably, in connexion with the appointment of agents to keep way-bills, ensure a sufficient revenue to meet all demands upon the road for motive power. In the following estimate of the amount required for motive power, during the ensuing year, I have endeavored to include every expense that can be anticipated. It is still probable, however, that the rapidly increasing trade, on this great thoroughfare may require additional expenditures, which cannot, at this time, be foreseen, but which may be found absolutely necessary before, in the ordinary course of business, a second legislature could act upon them. It seems to me, therefore, highly important that some especial fund should be provided, by which (if necessary) the agents of the commonwealth could meet any extraordinary demand upon the motive power, such as the opening of other railways, which connect with the Columbia line, and which being in the progress of construction, would create. Estimated amount required for the ensuing year. Fifteen additional locomotive engines and tenders, at $6,400, Tools, machinery, &c., for same, Additional water stations, reservoirs, &c. Turn-outs, crossings, swivels, &c. Sheds for night stands, at water stations, $96,000 2,000 4,000 1,800 1,500 2,000 Additional set of ropes at inclined planes, If no arrangements should be made with a view of avoiding the planes, a second set of stationary engines will be required, which, with their erection, will cost, To which should be added the covering of the planes, recommended in my last report, Total, 3,000 $110,000 16,000 25,000 $156,000 Having in previous reports expressed my opinion in relation to the manner of using this railway, I deem further remarks on that subject unneces sary. The cars being at present owned by individuals, are generally kept in good condition, and owners appear uniformly well disposed toward making such repairs, or alterations, as they are from time to time directed to make. M. Brunel's mode of constructing arches without centering. The principle, which was originally adopted, and its efficacy ascertained, in the formation of the shaft of the Thames Tunnel, is founded upon the cohesive power of Roman cement, coupled with a system of ties, the most eligible substance for which, from a series of experiments performed by M. Brunel, appeared to be hoop iron. The piers having been constructed in the usual manner, it is proposed to pin, or secure, to them a mould for the purpose of determining the contour of the arch. A narrow rib may now be carried over, and keyed, using cement (with the occasional insertion of ties), which, by its adhesion to the brick being greater than the cohesion, enables the arch to be carried to any extent within the lim its of the strength of the material. The several arches being in succession, once keyed, they will be in a state to receive the whole of the ma terials necessary to the completion of the bridge. The bridge of the Santissima Trinitá at Florence was particularly adverted to, as affording a inagnificent example of rubble construction, and the durability of the material. The arches are composed of a mass of irregular stones embedded in mortar, having the consistence of a single stone, or of two stones abutting against each other at the crown. Lond. Archit, Mag., April. Cast and Wrought-Iron Wheels.--It was stated at a meeting of the Institution of Civil Engineering, that where cast-iron wheels on rail-ways would only last six or eight months, wrought-iron would serve at the same work three or four years. The wear of the Manchester and Liverpool line was stated to be 1-20th of an inch in depth per annum. The flanges rarely come into contact with the rails; one of the oldest wheels being taken off a carriage, the marks of the turning tool was found on the flange. Mechanics' Register. INVENTION OF THE MARINER'S COMPASS. Lon. Mech. Mag. The invention of this precious instrument has hitherto been awarded |