1 provement of the Canal should take place, the width of boats to proper limits than now bility and expense of changing the presnet is, that a large Canal is not only desirable exists on the Erie Canal. It is quite ap line. The survey shows that a new line and beneficial, in reference to the amount parent that the boats are now too wide for may be located, commencing below the of tonnage which may be carried upon it, the present Canal. Boats are constantly junction, and connecting again with the prebut because it materially lessens the ex- coming in contact with each other, or are sent line a short distance above the Nine pense of transportation. This circumstance driven against the towing-path by the pass-Locks. By this location, the lifts are dif axerts an important influence in increasing ing boat. Much injury to boats, and some ferently arranged, and one lock is dispensed the amount of tonnage on a Canal. It interruptions to the navigation, are occasion-with. On this line, the work could be percreates an accession of business, and con-ed by this circumstance. This difficulty formed without interfering with the present sequently enlarges its usefulness to the should be obviated on the enlarged Canal, country through which it passes, in the as the injury would be more extensive by transportation of coarser and cheaper arti- reason of the greater magnitude and weight cles, and extends the business in a relative of the boats. proportion over a larger district. The enlargement of the Canal and locks to the proposed dimensions will lessen the expense of transportation, exclusive of toll, about 50 per cent. This difference applied to the business of the past year, assuming the aggregate expense of transportation to be 20 per cent. greater than the gross amount of tolls, (which is believed to be a low estimate,) would be a saving of $826,007 81, and in ten years, calculating the same rate of increase to the tolls that has taken place in the past ten years, it would amount to $12,793,221 30. At a meeting of the Canal Board on the 23d of November last, the Canal Commissioners submitted the report of Nathan S. Roberts, John B. Jervis, and Holmes Hutchinson, who had made the necessary examinations in reference to the most favorable location for a new aqueduct over the Genesee river at Rochester, and also for a suitable location for a new weigh-lock. Their report is herewith submitted. In the fall of 1834, the Canal Commissioners had adopted a plan for constructing a new aqueduct on the present location, by turning new arches under the old ones, and The enlargement of the Canal is intimate-extending them a sufficient distance above ly and necessarily connected with the utility of a double set of lift locks, and hence the propriety of commencing the work as soon soon as practicable, and of prosecuting it with as much diligence as the funds appropriated to this object will admit. The funds at the disposal of the Canal Commissioners for the purposes of the law under which they are now acting, will be too limited to justify a commencement of the work on every part of the line, and as speedy a prosecution to its completion as an unlimited appropriation would admit. It is therefore deemed advisable to confine the operations to the line between Albany and Syracuse, until such time as the funds will justify a beginning on the other parts of it, without interfering with the speedy completion of the work on the line above referred to. This arrangement will render available the advantages of the enlarged Canal before the whole is completed, as it would no doubt be a saving in the expense of transportation to tranship the cargo in most cases from the small to the large boats. and below the present aqueduct, to obtain line. The surveys which have been made indicate that several important deviations may be made from the present line of the Erie Canal, to wit: a continuation of the new line, which has been mentioned, diverging from the present line below the junction, to the head of the four locks above the Cohoes Falls, and from thence, on the south side of the Mohawk River, to its intersection with the present line above the upper aqueduct ; from four miles above to one mile below the Schoharie Creek; a new line passing through the village of Rome; an extension of the Geddes level to the level west of the village of Jordan, by which the Jordan summit would be avoided; a new line from the lock west of Port Byron to Montezuma, with a view of taking a feeder from the Owasco Creek, below the flouring mill of Beach & Co.; and a new line east of Rochester, in order to avoid a great bend in the Canal at Brighton. With the proposed enlargement of the The examinations which have been made Canal, the present location of the aqueduct are not sufficiently matured to enable the in several respects would be objectionable. Canal Board to determine the question af The short curve in the Canal at the east end fecting the alterations; but they may result of the aqueduct, renders the passage of in the opinion that the public interest reboats inconvenient. This objection would quires them to be made. If so, the alterabe much more formidable for large boats. tions on the eastern section must be made The width of the water-way in the aqueduct next season, in order that the new locks could not be increased without material in- may be put under contract. It will be seen jury to the extensive flouring mills of Harvy that if these alterations are made, a new CaEly, on the east side of the river, of Thomas nal, on the enlarged plan, must be constructKempshall, on the west side, and the re-ed simultaneously with the locks. moval of the flouring mill lately owned by Benjamin Campbell, on the south side of the aqueduct. In connexion with the changes which are indispensable to the enlargement of the Erie Canal, according to the proposed plan, By referring to the report of the En- the Canal Board are deeply impressed with gineers, it will be seen that lines for two lo- the importance of making such other imeations have been surveyed: the one com-provements essential to its usefulness, as mences 200-feet, and the other 300 feet shall be commensurate with the means and above the present aqueduct, on the east side interest of the State, and the character of of the river, and both connect with the the most important artificial communication The proposed width of lock will permit Erie Cenal at the same point en Exchange- in the world. the convenient passage of boats 17 feet street, on the west side of the river. The wide, and a little exceeds the transverse first line above the aqueduct has been ratio of boat and Canal most favorable to the adopted. On this location the curve in the power of traction, but is about six feet nar- Canal at the east end of the acqueduct will rower than would correspond with the pro-be much improved. An entire new work portion which the present locks bear to the Canal. It is stated that the locks on the present Canal to conform to the rules governing the "economy of traction," should be a little less than 10 feet wide, and the cargo but 32 tons; whereas, 45 or 50 are sometimes to be advised on the score of economy. will be constructed, better in its appearance, The present location of the nine locks above the junction, has not left sufficient It should, however, be borne in mind, pound reaches between them for the conthat on a Canal as large as the one pro-venience of navigation. To lengthen and posed, where the business is such as to re-double these locks, will increase this inconquire the frequent meeting and passing ofvenience. To obviate this objection, the boats, and sometimes three abreast, there Canal Commissioners directed a survey, is a much greater necessity of restricting for the purpose of ascertaining the pratica The Canal Board, however, duly appreciate the propriety of making no deviations from the present life, that are not clearly sanctioned by considerations of public utility. Investments and various improvements have no doubt been made on many parts of the present line, under the expectation of its stance should not be permitted to operate continuance; and although this circumagainst the interest of the public, it is entitled to a respectful consideration. Dated, Albany, January 23d, 1836.7 S. VAN RENSSELAER, JOHN BOWMAN, JOHN TRACY, A. C. FLAGG, A. KEYSER, From the London Mechanics' Magazine. On the Great Western Railway Bill. Were these prepared by you?-Yes. I was asked whether the summit level of the line had any necessary connexion with the power necessary to work it, and I drew these specimens to show that there might be two lines, one of which has a very high summit, and the other a very low one, and yet which require the same total power to work them. And the sum of the ascents upon the undulating line on the last plan are greater than the sum of the ascents on the other?-That is not necessarily a test. Is it not the case with this section?-It may be so; I have not measured it; that is not the test. Explain how it is that less power is required to attain the higher summit?-If you add together all the perpendicular heights that the load has to be lifted in ascending, and then subduct from it all that falls upon an acclivity which is not more steep than 1 in 250, you will then get a number of perpendicular feet which the power is to overcome; but, in addition to that, it will be neJust produce them, and explain them?-cessary to take those descending slopes which If you suppose this section, No. 1, to repre are more steep than 1 in 250, and allow for sent two roads, one of them consisting of them as giving back so much power as they one continuous slope rising 1 in 300, and would give back if they were only 1 in 250, then one descending slope of 1 in 300, and and then you get the number of perpendicuthen another, with the same termini, consist-lar feet that the power is to overcome. The ing of six short ascending slopes of 1 in 300 loss arising from steep slopes consists in interrupted by six descending slopes of 1 in this, that any descending plane more steep 300,-I take 1 in 300 as an example mere- than 1 in 250, will only give back as much ly, the power necessary to work these power as it would give back if it was 1 in would be precisely the same. 250; the consequence is, there is a number of perpendicular feet lost wherever there is a steeper incline than 1 in 250. According to the plan you now hold in your hand, though the lower line, the darker line, attains so much lower a summit level than the lighter line, the same power is required to surmount the one as the other?Yes; the one is a succession of summits, and the other one only; and to compare these it would be necessary to bring all the ascending slopes to one end, and all the descending to the other, and on comparing you would then find them the same. Does not it follow, then, as an inevitable conclusion, that the mere suminit level of two sections does not of itself afford any thing like a conclusive estimate of the power necessary to surmount that summit level? -Certainly not. One in 250 is the point of rest?-That is the angle of repose. Mr. Talbot.-Is that taking all the slopes upon our line?—Yes; including Eustonsquare and the Box-plane. Mr. Joy.-If it has been stated in evidence by Mr. Locke, that there are fewer accidents on the descending slope upon the Manchester and Liverpool Railway than upon other parts of the line, would not that answer-I do not mean intentionally-be fallacious in this respect, that the length of the line is about thirty-one miles, whereas the length of the incline is only about a mile and a half?-The fact that there are more Witness handed in the following paper : accidents on that slope than on any other Calculation of the Amount of Mechanical portion of the line of equal length, is notoPower necessary to draw a Ton from Lon-rious. don to Both, and from Buth to London, on the Great Western and Basing Lines, the Power being expressed in the equivalent Number of Pounds raised Three Feet high. "GREAT WESTERN RAILWAY. Feet. ...383 Sum of all the rises..... Fall at Box-hill, estimated at 1 in 250............... A plan which shall show two summit levels, one twice as high as the others, may not give any thing like a fair estimate of the power required to surmount the two?-You must not judge by the summit level-very || Distance from London to Bath.... .. . . little depends upon that. Friction at 9lbs. per ton in pounds raised 1 y'd. Is it not obvious that a much higher sum-Power to raise 1 ton 88-02 feet... mit level may be obtained by less power than a lower summit level, if, in attaining the lower summit level, you have more objectionable inclinations ?-Yes, every thing depends upon the graduation. ......... Resistance from London to Bath in pds. "Bath to London. Sum of all the rises..... 140 51.98 You cannot fairly compare that plane with the whole line?-You cannot compare that one mile and a half with the twenty-eight miles. Mr. Joy.-Have you some other tables marked 4, 5, 6, and 7, which you have prepared ?—Yes; I wished to verify the result of the calculation, as it would be satisfactory to make them prove themselves, by making a calculation of the same thing, by two different processes and formularies, so that it should be seen, that it was not 88-02 only arithmetically right, but right upon Yards. principle; and I have proceeded to obtain 192,588 the total mechanical power necessary to coincide so nearly as to perfectly verify each work the lines by both methods; the results 1,733,292 65,722 .1,799,014 Feet. ....364.5 27.5 So that if power be lost on the lower more Sum of all the fulls, not exceeding 1 in 250....337 than the higher summit level, the mere surface would be calculated much to mislead? -It would not mislead scientific men or engineers. But to mislead a common spectator?Yes, people not acquainted with the subject. In the section you have exhibited, No. 1, you say the same power would be required for the two lines?—Yes. You have another marked 2?—Yes; in which the lower would require the greater power. That is, the lower and darker section would require a higher power than the upper?-Yes; the slopes are more steep. Yet they both start at the same point? Yes; and one is a higher summit level than the other. Effective fall of Euston-square incline........ 15-91 11:59 Yards. Friction at 9 lbs. per ton in pounds raised 1 y'd. 1,733,292 8,654 Total resistance from Bath to London in Effective fall of slope 1 in 202... Feet. 299 other. [The witness delivered in the tables referred to.] Are these tables illustrative of the speed? -These tables include the speed which the road would be traversed with, subject to two different conditions: one, that the maximum speed is limited to thirty miles, and the other to forty miles an hour: they also state the length of line in yards, and the mechanical power necessary to overcome every slope. On each line?—Yes, expressed in pounds weight raised a yard high; they also express the resistance in pounds per ton every slope, from one end to the other. Backwards and forwards?—Ycs. What are the termini ?-Euston-square and Bath. Not Bristol in either case?—No. Mr. Joy. Taking the speed in the first 1416 instance, as not exceeding thirty miles an hour for the maximum, what time would be consumed upon the Great Western from 157-41 London to Bath ?-From London to Bath on the Great Western would take, on that supposition of thirty miles an hour, four hours fifty-five minutes twenty-three seconds; on the Basing line, four hours fiftynine minutes and fifty-seven seconds; and from Bath to London on the Great Western it would take four hours fifty-four minutes Difference in favor of the ing slopes from London to Bath Difference in favor of the 0.1234 35.05 17.96 17-09 29.93 forty-four seconds, and on the Basing line Time of transit from London to Bath and from Bath to Lon- Difference in favor of the 9.84 . Length of an absolutely level h. m. s. 37 06 30 as the greatest allowable speed 9 30 5 9 18 23 Have you got the difference, if it was cal-Length of an absolutely level line culated at 1 in 250?—No, I have not. requiring the same quantity of Yards. 196,721 0 11 42 Difference in favor of the With a speed not exceeding forty miles from London to Bath?-Four hours forty-Effect four minutes and forty-four seconds on the Great Western, and on the Basing four hours forty-nine minutes and forty-seven seconds. Bath to London ?-Four hours forty minutes and twenty-one seconds. Basing-Four hours twenty-eight minutes and thirty-six seconds. London to Bath and Bath to London, the Great Western?-Nine hours twenty-five minutes and five seconds; and on the Basing, nine hours eighteen minutes and twenty-three seconds; the difference in favor of the Basing, six minutes and forty-two seconds. What rate do you assume on the level? -Twenty-five miles an hour. Is that for the forty?—For both. Have you got any other tables?—Yes. Do they relate to another point of your examination?-A comparative view of the two lines with respect to their average power and their greatest resistance: the results are here brought together. The results of the other tables are brought together?-Yes. The witness delivers in the following pa pers : Comparative View of the Great Western and Total mechanical power necessa ry to work the line both ways, calculated by estimating the resistance upon each successive slope from the table of gra dients, expressed in pounds the power necessary to work Have you calculated the length of a line absolutely level which would be mechanically equivalent to each of the proposed lines? -I have. What is the difference in favor of the Basing line?-The length of a line abso3,466,586 3,397,318 lutely level, requiring the same mechanical 69,268 power as the Great Western Line, would be 196,721 yards; and the length of a line absolutely level, equivalent mechanically to the Basing line, would be 188,739 yards. This is on the supposition that the greatest slope on the Basing line is 1 in 202, and in that case the difference would be 7,982 yards in favor of the Basing line. Have you calculated what is the average power of traction per ton required upon each of the two lines?—Yes, I have. The average resistance of the line worked both ways expressed in pounds per ton for the Great Western is 9.1879, and for the Basing would be 9 lbs. and 19-100ths for the 9.0645; that is, in more popular language, Great Western, and 9 lbs. 6-100ths for the Basing; that is supposing the slope to be 1 in 202, and taking into account the Euston London, exclusive of the Box- Comparative View of the Great Western and G. Western. Basing. Total length of the line, in yards 192,588 167,832 ...... per ton 9.1879 weight, lifted three feet high -3,540,965 3,397,316 Dfference of total mechan. ical power in favor of the Basing line Total mechanical power necessary to work the line both ways, calculated by allowing nine pounds per ton for friction throughout the whole distance, and then estimating the power necessary to lift the load through the sum of all the rises, and the quantity of this power restored by the sum of all the falls -3,540,960 3,397,320 Difference in favor of the Total length of the line in yards 192,538 Difference in favor of the Difference in favor of the ing slopes from London to Bath, Difference in favor of the ing slopes from Bath to Lon 35-05 17.09 17.96 Will have the goodness to tell me if you you have made any calculation of what force must be applied to the break in order to prevent an increase of speed down the Boxhill slope -The resistance that the break 0-1879 must exercise to oppose the descent of the load down the slope I stated to be 12 lbs. 17-96 per ton; then, in order to produce that, the break must be pressed upon the tire of the wheel with such a force as to give that resistance, namely, 12 lbs. per ton. Now the pressure of the break upon the wheel would 11.97 require to be from five to six times the amount of the resistance required, because don, thirty miles an hour being the proportion that the actual pressure of taken as the greatest allowable h. m. s. the break bears to the resistance, supposing speed. 9 50 7 9 43 37 it to be made of such a wood as elm, will 0 6 30 be five or six times, so that, if we want to produce a resistance of 12 lbs. a ton, we must press the break upon the wheel with a force amounting to 60 or 70 lbs. a ton. This is assuming the friction necessary 0 11 42 to retard going down the Box-hill ?—Yes. Time of transit from London to Now give me the same answer with re-which must be incurred in whatever way these || and passengers going both ways, am I not ference to the descent at Euston-square?slopes are worked. If it is worked by a sin-entitled to consider there is no consumption That is 1 in 86, I believe. The force down gle rope, I have not included the power ne- of vital air one way?Yes. a plane of 1 in 86 would be 17 lbs. per ton, and 5 times 17 are from 85 to 90 lbs. ; that would be the pressure necessary to counteract the whole resistance. cessary to pull the rope back, or to work the Is it ridiculous to suppose that ?-No. Is it not an absolute fact ?-Yes, it is. Then it ought to be as fifteen to nine ?How does it happen that the Great West-No, certainly not; not so far as regards any What means have you taken to verify the ern line has the effect of an ascent in both effect produced upon passengers. calculations you have made respecting the directions?-That is a very common con- You mean, when any effect is produced, mechanical power and other matter to be sequence of graduation. The line at the it is as thirty to nine?-If there happened satisfied of their accuracy ?-In my calcula- one end may be a number of perpendicular to be two trains passing at the same time in tions I have proceeded by two totally differ-feet below the other end, and the graduation opposite directions, all the passengers coming down would receive the ill effects as the passengers going up, without any one receiving any benefit from the de ent processes and formularies. In the one case I have considered the resistance that the power has to overcome from one end of the line to the other by the friction; this is 9 lbs. per ton; the total effect of that is a matter of easy calculation. I then consider separately the effect of all the rises and all the falls. In every rise the moving power must lift the whole weight of the train through the number of perpendicular feet in the rise; in every fall less steep than 1 in 250 a quantity of power is got back equal to the number of perpendicular feet in the rise; in every fall more steep than 1 in 250 the quantity of power is got back equal to the number of perpendicular feet which would be found if the fall was only 1 in 250. power that may be such that it may have the effect of Mr. Talbot.-Allow me to call your at- 66 scent. Do you mean to state, that with trains going both ways the consumption of vital air in the tunnel is in the proportion of thirty to nine, compared to a level ?—No, not with the same number of trains, but I have alluded to a single train during its passage. And during the ascent ?-During the ascent. Then with respect to those two trains going in different directions at the same time, the consumption of air would in this tunnel, with respect to another tunnel with the same length on a level, be as eighteen to thirty Yes. In favor of the level tunnel ?—Yes; but that is a thing never likely to happen. do not think that the shafts in the tunnel Having computed these, I then combine them with the result of friction; the latter is 9 lbs. per ton. I add them or subtract them, according as gravity assists or opYou did not add that. To a question, Are you not, in your calculations of the poses the friction, and the result is the total what would be the proportion of increase in effect of the noxious air given out, assummechanical power acquired to transfer the the consumption of fuel, you say, as thirtying that for a moment there is no draught? load from one end to the other, and I do this to nine. "In the same proportion as the Yes, I am decidedly of that opinion. I in both directions, and add the results, and increase of power?" Yes; I may assume get the total power both the one way and that the destruction of vital air and the prothe other; that is one way of calculating duction of noxious air is in the proportion Then I made the same investigation by an-to the mechanical power exerted?"Yes. other totally distinct method; in this case I took all the slopes from one end of the line to the other. I take the common method of expressing the resistance to the drawing power on each slope expressed in pounds weight per ton; from that resistance and the length of the slope I obtain by a simple arithmetical process the total power required to draw a load from one end to the other of the slope. Having done this for all the slopes from one end to the other of the line, I added the results together, and obtained the total mechanical power in both directions. Now, upon comparing the results of those two methods of calculation, you can see how nearly they coincide. Do you find them nearly coincide?— From Bath to London there is no difference in the calculations: they agree to the last unit. On the Great Western, and from London to Bath, there is a difference of 5 lbs. in rather less than 2,000,000 lbs. ; and on the Basing line, from Bath to London, a difference of 1 lb. other. I And only that?-Only that. Then the consumption of power up the mean? Descending?-Nothing at all; there is no power used in descending. If there be no power at all that way, may not say that, taking it both ways upon two trips in this tunnel, I have an average of fifteen to nine?-If you put it in that way. would be found to produce any good effect for the passing engine, though they will probably ventilate it for the next train; but the passage through will be so quick that no effective ventilation will have time to take place for the passing engine. Should you like a tunnel a mile long will not be found to be the best means, and without shafts ?-I think that the shafts my opinion is, that they must ventilate that subject ?-No, and no one has any Are you sure of that?—I do not know of That depends upon the object you have in locomotive on a slope; I am not aware of And this tunnel being to be used both ways, it is not fair to consider the quantity of noxious air and the destruction of vital air both ways?—Yes, provided that is the way you state it. Can you at all account for that slight I want to know whether you accede to You are a scientific gentleman of great difference?—Yes; it arises, most proba- that ?-I stated all the conditions, and my eminence put into the box to favor us with bly from a few decimal places being neg-statement alluded to the passage of an en- your opinion; I want your opinion?-My lected in the one case that were taken in the gine up the tunnel from one end to the other. opinion I have stated already, that I ap The passengers who descend being free from prehend shafts will not produce a material In the calculation you made, have you or annoyance, is no relief to the passengers as-relief for the passing train; they may, and not included the slope of 1 in 86, the Eus-cending. probably will, ventilate for the next train. ton-square slope, and 1 in 107 at Box-hill? That sounds very clear and very amusing In the transition of the train through a -I have included the power absolutely ex- to my learned friend; but when we are certain length of the tunnel, there is not pended in working the slopes, but I have not upon the consumption of vital air, practical-time for the ventilation to take effect. If made any allowance for the waste of powerly speaking, and trains working both ways, the atmosphere in the tunnel be, as it ge nerally will be, still, then the engine, as it|| Mr. Tallet-Why should not the train of carriages leave it behind?-So it will, and it involves the train; it is because they do leave it behind that it involves the passengers. Applications of Chemistry to the Useful Arts,|| Native Nitre Beds.-The salts containbeing the substance of a Course of Lectures ed in the nitric soils of Bengal, Ceylon and delivered in Columbia College, New-York, Egypt are, nitrate of potassa, (nitre,) niby James Renwick, Professor of Natura trates of lime and magnesia, sulphates of Experimental Philosophy and Chemistry.lime and magnesia, and common salt. In Continued from page 155. II. The leys obtained from the earth by passing water through it, until it flows off tasteless, are in these warm climates partly evaporated by exposure to the sun and air, and partly by boiling until the liquid is saturated. Ceylon the soil is mixed with wood ashes, and lixiviated. The water in its passage' dissolves, not only the saline matter contained in the soil, but the potash of the wood ashes, and by it the earthy nitrates History. The nitrates of potassa, lime, are decomposed and nitrate of potassa reand magnesia, are found in the soil in va-sults. In Bengal the advantage of the rious places, and are probably frequently use of alkaline matter does not seem to formed spontaneously. It is only, howev-be understood, and the earthy nitrates are er, in warm climates that they are gene- lost. rated in the open ground in sufficient quantities to make them profitable objects of extraction. In colder climates, these salts occasionally form, in quantities worth collecting, in caverns, in cellars, and in damp buildings of masonry. The nitric acid to form these three salts, is formed by the which unites with earthy and alkaline bases absorption of its two elements, (oxygen There would be from fifteen to twenty and nitrogen,) from the atmosphere. This feet between them and the roof of the tun-being suspected in France, a successful attempt was made to form artificial nitre beds, and thus a supply of this essential munition of war was obtained, when all access to the countries whence nitre had been previously obtained was prevented by the British fleets. Suppose it rises to the roof in a tunnel thirty feet high, how much will it be above the train of passengers?—I cannot recol lect the height of the carriages, twelve or fourteen feet. The chimney is fifteen ?-The carriages are very high; they go up a considerable height of the chimney. nel?-Yes. It is then poured into vessels The mother water contains the earthy niwhere on its cooling the nitre crystalizes. trates, (if not decomposed,) with part of the sulphates and of the common salt. But the crystalized nitre is by no means pure, containing a portion of the last named salts, as well as organic matter, which are usually, taken together, as much as 25 per cent. ARTIFICIAL NITRE BEDS. AUTHORITY-DUMAS. Chimic appliquee aux Arts. These have been formed in calcareous Do you think that this air is to rebound almost perpendicularly upon the train of carriages-I have no doubt of it, from the velocity with which it comes from the chimney. I may state that there is a jet of high-pressure steam turned upwards in the chimney; it is blown out of the engine, and it is presented perpendicularly upwards in the chimney. All the highpressure steam that works the engine is blown with prodigious violence up the chimney; this carries with it the noxious air, and they are driven against the roof of the tunnel with this force; they do not go up with their natural force of draught, but they are carried up and strike the roof with force of the steam, which is so considerable that they would come down upon the first carriage like a ball rebounding. I want to ask you to explain one thing, 1. The presence in the soil of powerful which to me requires explanation. You alkaline or earthy bases, such as line, mag-potassa thus formed, was obtained by con told their lordships that the acclivity of the slope had nothing to do with the strength of an endless rope, because it balanced itself?-Yes. Rationale. The theory of the formation of nitric acid from its elements, as they exist in the atmosphere, is not fully under- soils impregnated with animal matter, as stood. The union does unquestionably beneath butchers' shambles, and in ancient take place by the passage of electricity; burial grounds. But this method has gone and the rain which accompanies lightning out of use, with the necessities which gave often exhibits traces of the acid; but the it birth. The only operation necessary was quantity thus produced is not sufficient to to stir the earth frequently, so as to expose explain the large quantities of the nitrates fresh surface: to the air, and at the end of a which are found in some situations. We few months, a sufficient quantity of nitrate can only, therefore, state the circumstances of lime was formed to render the earth fit which experience has shown to be neces- to lixiviate. To the liquor, containing the sary in order to the production of these ni- nitrate of lime, common potash was added, trates. These arein sufficient quantity to insure the decomposition of this earthy salt. The nitrate of nesia, and potassa. 2. A certain degree of moisture, such as that in friable vegetable mould, after a gen tle rain. I should be glad to know how you ex3. An elevated temperature in the air, as plain that!If you put an endless rope at the freezing point, the nitrates are not over a pulley actually perpendicular, which produced, and the process is not active beis the extreme case and the greatest acclivi-low 70° of Fahrenheit. ty, and apply the power to it to put it in 4. The access of solar light, which seems motion round the pulley, you will require a to be absolutely necessary, although if it be certain force to do it; and if you put the so intense as to dry the soil, the action same rope upon a level it will require the same force, because the rope balances itself. If there was a pulley at the top of this room, and I put a thread over it in the one case, and a nine-inch rope in the other?--I am speaking of the same rope. You stated that the acclivity had nothing to do with the strength, from which I infer that the same rope will do; am I wrong? -No, provided it is to draw the same load not the same load because the acclivity makes a difference in the load, but I am speaking of the rope itself so far as the rope itself goes it balances itself. You mean with the same strain?-Yes. (To be continued.) ceases altogether. centrating the liquor by boiling, and crystalizing. It was in this manufacture, that the large quantities of potash exported from this country to the continent of Europe were principally used; and the consequent high price of this article had a most important influence upon the clearing of our forests, and bringing them into cultivation. In Sweden, the nitrate of lime is procured, by placing in a small wooden hut, upon a floor of wood or well rammed clay, a mixture of common earth, marl, and ashes, to the depth of two or three feet. This is thoroughly moistened with the urine of cattle, and stirred up once a week. 5. In temperate climates, animal matter disseminated through the soil must be present; and this is so essential, that, when artificial nitre beds were first formed, it was supposed that the nitric acid was altogeth- At Longpont, in France, a nitre bed is er derived from the organic matter. But formed in an ancient quarry in calcareous the quantity of the nitrates which are form-rock; in the bottom of this a bed of three or ed, is far greater than can be accounted four feet in thickness is formed of alternate for in this manner. It is therefore anala- layers of earth and stable manure, and the gous to the case of ferments, where by the washings of a stable are directed to it. At addition of a substance capable of entering the end of two years the mass is moved into fermentation, that action may be in- into the light, and is frequently stirred for duced in a great quantity of other fermenta-two years more, when it is fit for lixiviable matter, which might otherwise have re-tion. mained unaltered. In some places the earth is prepared for |