Box 2, Folder 7: Typewritten Letters, 1811-1828

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-ing and wording the matter scientifically.

I shall therefore submit the whole to your perusal and correction, and, if by that means I am able by stating facts to amuse any of your intelligent and numerous readers, I shall be wholly compensated for my trouble.

The navigation of the Ohio river, which is of itself the most important as well as most interesting waters of the west, is only obstructed by the rapids of this place usually called the Falls of the Ohio. In these rapids the river has a descent of 22 1/2 feet. in a distance of somewhat less than two miles, but in no case has it a perpendicular fall of more than three. At times of high water an acceleration of current, not usual to other parts of the river, is all that is perceived,- but at times of low water it cannot be passed by loaded boats without great risk and danger.

The direction of the river, above and below the rapids, is from northeast to southwest. The point where it meets the rocky obstruction which, occasioning the falls, gives it a direction nearly at right angles to the course above noticed, consequently gives it a more unfavorable and dangerous appearance. The necessity for a canal around these rapids, must have been felt ever since the Ohio river first began to be navigated by boats of any considerable size, and an attempt was long ago made to construct a canal on the Indiana side of the river, but it did not succeed very well.

In Jan'y, 1825 the present company was chartered with a capital of $500,000. to construct a canal around the rapids of the Ohio on the Kentucky side of the river. In December same, the work was put under contract to Collins, Chapman, & Co. (formerly contractors on the New York canal) to be completed by the 1st of November, 1837.

It commences at the lower end of a basin which extends along the bank of the river for the whole length of the village of

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Louisville and is connected with the river at its upper end. From the lower part of this basin, the canal traverses the point formed by the bend of the river at the falls and enters the river again at the lower part of the little village of Shippingsport. Its length is about two miles, fifty feet wide on the bottom, and its banks are forty two feet above the bottom, which is four feet below the surface of the water in the basin at Louisville, at the times of low water. A mark on a house in Louisville is said to be at the height of the highest flood known since the settlement of the place. This mark was found to be 40 ft. above the bottom of the canal, the banks are to be two feet above the highest flood. The whole amount of earth excavation, according to the original estimate is 687,000 cubic yards. This earth is to be excavated so as to make a slope of one and three fourths base to one rise. There are several modes reported to in this excavation of this earth, the most efficient is (as is usual on canals) with carts, scrapers, and wheelbarrows. The last of these is used when the runs are too steep to be ascended in the ordinary way, by fastening three or four of them to a rope, which, at the top of the bank, goes over two pulleys and is then drawn by an ox team parallel to the canal. When the burrows are at the top of the bank, the team is ready to retrace its steps and draw up a similar set of barrows on the other run, and so on alternately.

The amount of rock excavation originally estimated was 111,000 cubic yards--but a small part of it has been removed in consequence of the backwardness of the earth excavation. It extends the whole length of the canal varying in depth from one to ten feet, but on an average about seven feet. This is to be cut in a perpendicular manner making the bottom of the canal fifty feet wide, consequently we have a horizontal berme on the surface of

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the rock, which is more or less, according to the depth of the rocks and serves as a foundation and commencement of a pavement which extends to the top of the banks. This pavement is necessary to prevent the abrasion of the banks by the motion of the water produced by the wheels of steamboats, &c. The excavation of rock is done by drilling and blasting, and is afterwards raised from the canal by the use of a crane, of the same construction as those used on the mountain ridge of New York., invested by Mr. Orange Dibble. Of this crane I enclosure a figure. (Sketch -No. 4).

There are four locks, three lift locks, and one guard lock. They are all combined and situated at the lower end of the canal opposite Shippingsport. The guard lock is 190 feet long and 50 feet wide in the chamber. Its walls are 42 feet high, 13 feet thick on the bottom, and 5 at the top,-their upper ends are semi-circular with a radius of 13 feet. The three lift locks have a lift of about 9 feet each,- they are of the same dimensions in the chamber as the guard lock. Their walls are 20 feet high and 8 feet thick at the bottom and 3 feet at the top. The upper gates to these locks are sunk 4 feet below the canal, a lock above so that the water can be discharged through them to fill and empty the lock without inconvenience to passing boats. Culverts of sufficient size, through the walls in the canal way, would too much weaken them. At the time of the last annual report of the President and Directors, of the Louisville and Portland Canal Company, it was expected by them that the canal would have been completed by this time. But they have been disappointed as will be seen from the following statement.

Of the 687,000 cubic yards of earth 141, 000 yet remain to be excavated, ~44,000 is about the number of perches of mason work to be laid in the locks of which only 12,000 have been laid.

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Nearly all the rock is yet to be excavated. One stone arch bridge is yet to be built, where the turnpike crosses the canal. A pavement extending from the top of the rock to the top of the bank. Upon the whole it is considered about half completed.

As a cause of this backwardness of the contractors, perhaps it ought to be mentioned that there is a great difficulty in getting laborers in this part of the country and particularly in the summer season. One more year has been allowed by the legislature for the construction of this canal. But whether it will be completed within this time is a matter of some doubt.

Having thus completed my description of the canal, it may not be unacceptable to add such observations relating to the geology of the country about the rapids, as I have made, imperfect as they are they may have their use. Of the rock strata there are four:

1st. Limerock, probably the common compact lime rock, -as to the depth and extent of this rock I am unable to set any limits. It passes under the slate rock in the bank of the river below Shippingsport, but whether it rises again I do not know. It contains a great variety of Petrifactions. The minerals which I have collected from it are few and common,-the principal are quartz crystals, calcareous spar, and sulphuret of iron. Several springs issue through it, most of which contain a considerable quantity of Oxide of Iron held in solution by means of Carbonic Acid. This has induced many persons to ascribe valuable medical properties to them. When newly exposed to the air the rock continually gives out an agreeable bituminous odor, occasioned by petroleum or Seneca oil, which is found filling the cavities."

In some rare and small places this rock is composed of small six-

*First published notice of this important fact. H.W. Michell--P. 18 Am. [? 1894)

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sided cells, resembling honeycomb, generally covered with the bituminous oil above mentioned. As respects the origin or cause of the honeycomb rock, contrary to the opinion of many persons with whom I have conversed on the subject, vix. that it is real honeycomb petrified, I suggest the idea those six-sided cells were formed by numerous small air bubbles, formed there when the rock was in a plastic state. This may be the visionary imagination of a boy, suffer it to be so, and should it be considered by you as absurd or incorrect, do correct it, or anything else you think proper; or in other words I have not seen it explained in a similar way by any author I have access to, although it may not be new. It is this rock which forms the rapids of the Ohio. The stratum descends towards the west, the edge of it projecting above the surrounding country, would form an obstruction to the river, which would continue to rise until it ran over at the lowest place and then regaining its former level it would form rapids.

Instead of continuing in its course it would run down in the direction in which the stratum descends; or at least it would tend that way and gradually adapt its course to it. A variety of this lime rock forms when calcined in the usual way, a cement, which has the property of getting very hard under water, hence the name water lime rock has been given to it. A thin layer of coarse grained lime rock, probably the Oolite or roestone lies immediately on it. It forms a small island opposite Shippingsport called Rock Island, and is quarried from the lock pit at the lower end of the canal. Its color is blush-gray; fracture conchoidal; adheres slightly to the tongue; emits an argillaceous odor when breathed upon; and it effervesces with acids. When calcined it is a buff color and does not slack with water like common lime but is ground for use in a steam mill erected for the purpose. It is used in the construction of the lock and other mason work in the canal.