the same offsets apply equally well to the continuation of the tangent on the other side of the point of tangency, the table is calculated for stations of 400 feet and for radii of from 379 feet to 137,500 feet. The offsets are those parts of the secants between the tangent and the circumference, or the secant less the radius, and are measured towards the centre of the cir cle. It is therefore necessary to know their inclination to the tangent, and the columns of angles and offsets are placed in juxta position in the table. These tables are adapted to approximate locations, final locations, to laying the rails on the main line or in turnouts.

It is stated by Mr. Simms in the Civil Engineers' and Architects Journal for July, 1839, that he hopes shortly to publish a table of ordinates for setting out railway curves from tangents, which he has himself used for some years in England, and a table less complete than the one now offered to the public by Mr. Johnson, has been used on different public works in this State. The usual mode has been to run out as many chords, of one chain each as could be seen from the origin of the curve; then to remove the goniometer to the station last determined, and proceed as at the origin. By the method of ordinates to long tangents inuch time is saved, and the number of angles to be measured is reduced, on ordinary ground, to about onefourth of the number required by the usual mode. The table gives also the lengths of arcs to tangents of 200, 150, and 100 feet for the different radii.

The latter table will enable the young engineer to lay out any curve required in practice, with all possible accuracy, and, by means of the former, he will readily ascertain whether the curves so run will satisfy the other conditions of excavation and embankment, and if some modification be required, the table of ordinants will aid him in determining on the different degree of curvature required to place the line on the best ground. We have here, within the compass of a few pages, all that an assistant, familiar with the instruments, requires to enable him to locate a line and determine the quantities of excavation and embankment, and, as there are no similar tables published in this country, we have no doubt that these manuals will soon come into very general use.

The following abstract of a report made by "the Committee of Science and the Arts" of the Franklin Institute, Philadelphia, has been furnished us for publication.

46

The Committee on Science and the Arts, constituted by the Franklin Institute of the State of Pennsylvania for the promotion of the Mechanic Arts, to whom was referred for examination Dr. Edward Earle's method of preserving timber, "Report."

[The "Report" being long, and a considerable portion of it, although a

necessary part of the whole, irrelvant to the main purpose; an abstract of it may suffice to show the proceedings of the Committee, and the conclusions to which their investigations, experiments, and reasonings have conducted them as to the nature and qualities of the means employed, and the probable advantages and value of the "process."

Composed of many of the most distinguished members of the Institutesuch as President A. D. Bache, Messrs Boothe, Peale, Frazer, Merrick, and others the above Committee may be considered as constituting, in matters of science, the highest tribunal in our country, and the sanction of its approbation must go far to establish the character of those inventions and improvements on which it is conferred.

Having adverted to the form of the process, the materials used, and the mode of applying them, together with the different kinds of decay to which timber is liable, and which they agree with others in attributing to the gasseous, alluminous, and glutinous substances inherent in it;—they give a short history of the attempts which have been made in different countries to prevent or cure this costly evil. They proceed then to detail their own experiments made to determine the relative effects produced on the putrefactive constituents of timber by the sulphates of iron and copper and by corrosive sublimate, which salts they find to act similarly and equally, and are considered by them as the materials most powerful in their preservative agency; and also their experiments to ascertain the introduction of the sulphates by the proposed "process," into the body of different kinds of wood. In the course of the experiments made for these several purposes, the Committee satisfy themselves of the following results, most affecting the subject, which we give in the language of the "report" itself.]

"1st. That if these salts-the sulphates of iron and copper-penetrate the wood thoroughly, according to the process adopted by Dr. Earle, we have an economical substitute for the mercurial compound-the corrosive sublimate."

"2d. That the solutions are carried through the pores of the wood is conclusively shown by the experiments (detailed) on pieces taken from the interior of large pieces of timber which had been boiled with the solutions, The pieces were further split in half and the experiments made on the inner surface."

"3d. That heated solutions of various salts, such as corrosive sublimate and the sulphates of iron and copper, operate by expelling the gasseous matter and rendering the albumen and gelatine inert in all the parts of the wood which they penetrate."

"4th. That they-the sulphates-penetrate different woods in different degrees, ash being more thoroughly impregnated; hemlock nearly the same; hickory less so; and oak still less."

5th. That the sulphates of iron and copper produce the precipitation of albumen equally well with the perchloride of mercury-corrosive subli mate-and that of gluten in a nearly equal degree; and that they are there

fore to be considered as an excellent and economical substitute for that com

pound."

"6th. That therefore the penetration of wood by these salts-the 'sulphates of iron and copper-renders it less subject to decay and the attacks of insects."

"7th. That although theory and experiment thus go to show the diminished destructability of the wood, experiments on a large scale should be instituted in order to ascertain the correctness of these views of the committee, without which they are of little value; but that the subject is one of sufficient importance, and the probability of success sufficiently strong to warrant the performance of such experiments with great care, and with less regard to the primary expense."

"8th. That lime penetrates wood in a similar manner"—[but the opinion of the committee as to the effect of lime on the wood being less favorable, their experiments and reasonings are not thought important to be communicated.

The process is conducted by means of boilers and wooden tanks, which, in size and cost, may be accommodated to any purpose-whether it be to prepare posts for fencing, or the largest ship timber; and is capable of reducing timber, in a few hours, from a perfectly green, to a perfectly seasoned state-a short time being allowed after the operation for drying. The efficiency of this method, it is believed, will prove at least equal to any that has ever been tried; while the facility with which it may be practised, and the trifling cost of it, give it powerful claims to general acceptance. The materials employed being inexhaustible, too, and not liable to fluctuation in price, can never occasion an augmentation in the cost.]

Philadelphia, January, 10, 1840.

EDWARD EARLE, Patentee.

Applications for the use of his patent &c., may be addressed to " Dr. Edward Earle, to the care of John C. Montgomery, Esq., President of the Little Schuylkill and Susquehanna Railroad Company," or "Wm. Rawle, Esq., Counsellor at Law, Philadelphia."

For the American Railroad Journal and Mechanics' Magazine.
INTERNAL IMPROVEMENTS OF NEW YORK.

NO. 3.

In the two preceding numbers it was shown, and it is believed conclusively, that the enlargement of the Erie canal on the plan and to the dimensions proposed, is not now required, to accommodate the business upon it, and will not be for many years to come. Want of capacity, however, is not the only ground on which the enlargement of the canal has been advocated. It has been urged as indispensable to a reduction of the cost of transportation, and it is asserted that the saving, when the canal is enlarged to the dimensions as adopted, will be full 50 per cent., or one half the present prices. Should the inquiry be made from what data this inference is drawn, no bet ter answer could probably be given than the very unsatisfactory one of its

being the opinion of gentlemen who were selected to examine and report upon the subject.

It will scarcely be credited that a measure of so much importance as that of the enlargement of the Erie canal, involving an expenditure of more than thirty millions of dollars, should have been undertaken without instituting the most rigid examination into the merits of the project, and particularly whether so vast an expenditure was essential to effect the leading object proposed to be attained, viz. a reduction in the cost of transportation so as to render the expense as nearly as possible a minimum. Such, however, appears to be the fact.

The great importance of determining in the very outset of such an investigation by suitable experiments, the dimensions of the canal and boats, adapted to the most economical use of motive power, is too obvious to need illustration, yet we are not aware that a single experiment was made by those whose duty it was to conduct such an inquiry, with a view to this object.

The information which it is natural to suppose would have been first sought for as essential to arriving at just conclusions on so important a subject was not obtained, except in a very vague manner and hence was not of a character to entitle it to any very great degree of confidence.

The only experiments to which any allusion is made in the reports are those of the Chevalier Du Buat. These experiments were made upon a very limited scale, "in a canal varying from 23 to 6 feet in width, and from 14 to 24 feet in depth. The boats used were prismatic in forin, with square ends, the immersed part varying from 1 to 13 feet in depth, and from 1 to 2 feet in width." The velocity at which the boats moved was not given. It was from such data, principally, that conclusions were drawn in respect to the most suitable dimensions for the enlarged canal.

It will not be surprising if from such crude data, the authors of the several reports arrived at very different results. Two, at least, of their number advocated an enlargement to the size of 80 feet width of surface by 8 feet depth, with locks 16 feet in width and 115 feet in length-while others were somewhat more rational in their views, but still erring and differing greatly in their conclusions.

In one report it was stated, that the burthen of a boat best adapted to a canal 60 feet wide and 6 feet deep, with locks 15 feet wide and 105 feet long, was 103 tons, in another it was put at 79 tons.. In the estimated cost of transportation there was also considerable discrepancy.

We cannot avoid again expressing our surprise that these different opinions, based as they were in a great measure on mere conjecture, were con sidered sufficient for establishing the dimensions of one of the most stu. pendous works of the age-a work which was to cost millions, more es. pecially as it was so easy a matter to have tested by proper experiments on the canals already in operation, the actual practical loss or gain of any change in dimensions which might have beeu proposed. Experiments of

this description were not made, nor were they recommended, although the expense would have been inconsiderable.

The dimensions established for the enlargement were those of 70 feet width of surface and 7 feet in depth. This result seems to have been reached, not by any systematic course of reasoning or logical deduction from well established data, but by the very singular process of taking the average, or splitting the difference of the several opinions advanced in the reports.

It is not unworthy of remark, as indicating the enlightened view taken of the subject in the reports alluded to, that in the several dimensions proposed, the ratio of the width of surface of the canal to its depth was assumed invariably the same, viz. as ten to one, corresponding with the present proportions of the Erie canal, which was undoubtedly taken as the standard. Upon this principle, a canal ten feet wide should be only one foot in depth, and a river one mile in width, to afford the most perfect navigation should be 528 feet in depth !

In the ratio proper to be adopted between the width of the locks and the canal, similar erroneous views were entertained and advanced in the report, and but for the representations of a third person, incidentally elicited, whose reasonings upon the subject could not be controverted, we should, in all probability, have witnessed the singular inconsistency of a canal 70 feet wide with locks only 16 feet in width or what would perhaps have caused still greater surprise, we should have witnessed the entire destruction of all the locks on the present canal, which are now 15 feet wide, and built of masonry, for the purpose of obtaining only one foot additional width!

Assuming that the ratios of the boat and canal which afford the least resistance as deduced from the experiments of Du Buat are correct upon the scale of the magnitude contemplated in the enlargement, it does not follow that an increase in the dimensions of the canal from its present size of 40 feet wide and 4 feet deep, to 70 feet wide and 7 feet deep, is essential to effect the desired saving in the cost of transportation. To render the resistance a minimum, or the same that it would be on an indefinite expanse of water, it is requisite according to the rule given by Du Buat, that the width of surface of the canal should be 4 times the width of the boat, and the transverse section of the canal 6.46 times that of the immersed part of the boat. These proportions, it should be distinctly borne in mind, are independent of the absolute size of either the canal or the boat, and hence are as applicable to small as to large canals. This fact has evidently been wholly overlooked by the advocates of the enlargement. One of the principal sources, therefore, to which we are to look for a reduction in the expense of transportation is not dependent upon the magnitude of the canal, but is quite as attainable on a small canal as a large one.

The width of the Erie canal is 40 feet, the locks 15 feet, and the boats about 14 feet. If the latter are proportioned to the width of the canal, ac.