NEB&W Guide to Canals

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Scenery, Structures & Details Table of Contents

Introduction

The word "canal" is derived from the same Latin root ("canalis") that gives us "channel." (The Latin word was derived from "canna" meaning pipe, and gave us "cane".) Astronomer Percy Lowell at the turn-of-century was interested in the reports of markings seen on the surface of Mars by an Italian astronomer, but Lowell translated the word as "canal" (i.e., artificial, therefore made by intelligent life) when only channel was meant. Lowell spent the rest of his life mapping out the Martian canal system by squinting through the best telescopes of his day, but space craft have shown these straight lines were entirely an optical illusion.

The entire history of transportation over the last two centuries has been to increase the available horsepower while shrinking the size of the power unit. Parallel with that has the development of the travel surface to make best of the power. The original steam engine of James Watt's time was too big and so underpowered it could only be used as a stationary power to pump water out of coal mines. With improvements, it was eventually capable of moving itself. Of the initial attempts, the first practical one was on a boat, where it could be made big enough.

Water transportation has several parameters that are different from that on the land. The friction is so small that even a slight breeze is sufficient to move a vehicle. However, the friction increases rapidly as the speed moves up, as the water has to get out of the way faster, producing the familiar wake of a speedboat. Also, the bearing surface (water, of course) is self-leveling, and self-repairing.

In the November 21, 1913 Railway Age, there was an article by Harold Houston of the Rock Island on the comparison of freight train and canal boat resistance, using a dynamometer in the towrope to measure actual resistance. This was combined with studies done in Europe in 1895, perhaps the first time such a study was done.



Of course there are many factors which would change the resistance of an object in water (such as whether the object is streamlined or has a shape like a paddle-wheel). For a canal boat, the biggest would be the ratio between the underwater cross-section of the boat and the underwater cross-section of the waterway, in other words how close the boat fits in the canal.

Under one m.p.h., it was found to take less than a pound of pull to move a ton. At two m.p.h., the tractive effort had increased, from between one pound to three pounds. At 2-1/2 m.p.h., it took 1-1/2 pounds to over five pounds. At three m.p.h.'s, it was between 2-1/2 to well over 6 (off the scale). Trains with various weighed cars required just under three to just over five pounds per ton, but this stays virtually the same, at least up to 6 m.p.h. Thus somewhere before four m.p.h., canal boats and trains have equal resistance, with the canal boats drag doubling for every one m.p.h. increase. However, the top speed of canals of 1913 was two to 3-1/2 m.p.h., and anything over that tended to wash and erode the canal banks too much.

Looking at these numbers, it shows that with only animal power available, a canal was more efficient because at animal speeds, a given amount of horsepower (literally) could pull more if floating in water than on rails. At under one m.p.h., it was nearly twice as much. With the greater speed made possible by steam, railroads made more sense, all other factors being equal. (That canals required more earth-moving, were unusable in winter, and couldn't be brought up to the same speed as a train also tilted the balance to rail systems.)

The reason for the canal system is not as obvious as one might think. The idea was to make maximum use of available animal power. A horse or mule could pull many more tons if they were floated than over rough ground. The technology of the day was not able to produce a smooth land surface and keep it that way. Dirt roads rutted quickly.

Also, the animal power did not have to conquer grades. The whole idea of a canal system was not simply to create an inland water system, but to create a series of "spaghetti lakes" laid end-to-end, still ponds with no grades and no current. (If the current was three m.p.h., the boat has to be overcome the drag of four m.p.h. going upstream in order to move one m.p.h. in relation to the shore, which meant over five times the drag needed by comparison to still water.)

Of course, the major drawback was that each "lake" had to be absolutely level, which was beyond the earth-moving capabilities of the day. Therefore, locks had to be used to get from one lake to the next. A lock can be considered a solar-powered hydraulic elevator, relying on the sun's energy which has raised water (via a rainstorm) from sea-level to the mountain-top.

Another attribute of the canal system was the need for the towpath for the animals to supply the power. At some unusual locations, the canal boat could be given enough momentum to float across to another towpath, such as across a river. (A dam across the Delaware River at Lackawaxen, PA created a still pool, as the Company originally had "Lack-a-wampum" to build an aqueduct). However, this was an exception, and was a major bottleneck which was corrected in 1849 with one of John Roebling's pioneering suspension bridges to carry a wooden trough holding the water.

A similar crossing of a river, the mouth of the Schoharie on the Erie Canal, was eliminated at great cost in 1845 with a stone viaduct.

In Jim Shaughnessy's The Delaware & Hudson, there were pictures of the D&H canal running along the side of the Delaware River, but separate from the river. A canal system back then couldn't just connect the natural waterways, but had to be continuous its entire length. The original Erie Canal ran level and parallel to the Hudson River from Cohoes to Albany, a distance of about 10 miles, before terminating in Albany.

If you think about it, a canal has an even more important reason to follow a "water-level" route than the New York Central, and that means it will always in general follow preexisting water courses. Yet because of the low power system which could fight a current, the canal was kept separated.

Apparently the canal was made "two-lane" or twice the width of the barges, so they could pass at any spot without having to meet at a "passing track." (Had communications allowed some sort of signaling system, they could have built the canal with almost half as little earth-moving.) The locks were made just big enough for a barge, so therefore the maximum size of the "vehicle" was absolutely limited in both width and length. The D&H canal boats were so small at first that they were not "river-worthy" and the coal had to be trans-loaded at Kingston for travel on the Hudson River.

Because the canal was so narrow, and had earth banks for most of its length (i.e., an earth container), replacing the animals with steam-power was not practical. If the barges were speeded up, the resulting wake would damage the canal walls. As it was, the canal was lined with a natural hydraulic cement (I think another word for compacted mud in this case), and leaks were always a problem. The D&H canal lasted to 1898, but never was powered other than with mules. The only powered vehicle was a steam launch used for the paymaster, which traveled up and down once a week. It was narrow, so the wake had some room to dissipate before it hit the side walls.

The D&H canal almost lasted to 1900, but the company long had had a better way to "ship" items, over rails, so their canal system was simply abandoned. The Erie and Champlain canals were owned by the State of New York, which didn't own any parallel rail system. When technological advances were leaving the old canal system in the backwaters, they couldn't abandoned it for another of their transportation system. Instead, they "canalized" the rivers.

The New York State Barge Canal used the parallel water ways, namely the Hudson and Mohawk Rivers, instead of the previous separated still lakes of the old canal system. Steam and later diesel-powered tugs had enough energy to deal with current, although part of the project was to build a series of dams along the Mohawk to tame it somewhat.

From an article in the July 16, 1915 Railway Age, the dimensions of the NYS Barge Canal were given as 12 feet deep, an increase over the 7-foot depth of the last version of the Erie Canal. The locks were to be 45 feet wide and 328 feet long. The author (H.G. Moulton) went on to estimate that if all the costs of construction were added in, including rebuilding highways over the canal, damage claims, new port facilities, etc., the total cost would be $175 million. Dividing that by the total mileage, including the length of the Hudson, which was essentially "free" mileage, the cost per mile would be $340,000, compared to an average at that time of $60,000 per mile for a railroad.]]

Locks

Another technological advance helped the canalization in the matter of locks. In theory, there is no limit to how much a lock can change elevation. Normally there is a single lock at each location where the water-level has to be finally adjusted up or down enough to warrant the cost. At Waterford, NY, a series or "flight" (as in "flight of stairs") was used to lower the canal from the top of the Mohawk River to the Hudson. I believe some 7 locks were used, one after another.

The use of locks so curtailed the speed (I believe it took 24 hours to go from Schenectady to Albany via the Erie Canal, a distance of about 15 miles), that a radical solution was sought shortly after the opening of the Canal. An overland transportation system was proposed, following the portage route between the cities, more direct than the great crescent the Mohawk follows. This was to use rails for the roadway, and the company was chartered as the Mohawk & Hudson Railroad.

The reason for a flight of locks rather than a single one was that a lock has to have a gate made of wood, capable of holding back the weight of water when filled. How much water was a function of the elevation between the two canal levels connected by the lock.

The NYS Barge Canal was able to use steel gates, which being stronger, could hold a greater pressure of water. I believe that the three original locks of the Champlain Canal in Waterford were replaced with just one for the Barge Canal.

Power Canals

The year after the opening of the Erie Canal in 1825, the Cohoes Company was founded. Two of the founders, in fact had been involved in the Erie Canal. Canvass White was one of the three major engineers, and Stephen Van Rensselaer was a promoter and chairman of Canal Commission. (That Van Rensselaer owned vast tracts of land in the immediate area which would benefit from a vast manufacturing center arising in Cohoes, helped fuel his interest.)

The idea was to take water from the top of the Cohoes Falls and distribute it throughout the city to a series of rectangular ponds. Each pond drained to one lower by some 18 to 23 feet, and a factory built there could use the resulting water power. The company started with the idea of being a manufacturer, but shifted over the years to an overseer, landlord and power company to a number of other manufacturers. The company owned most of the land around their canals. They were able to decree that all the mills were to be built of brick or stone, and prohibited any dangerous or obnoxious operation such as a chemical or gunpowder factory.

Power was sold ("Mill Privilege") by a unit of water passing through a 10-inch square opening (analogous to electrical current) dropping by 20 feet ("voltage"). In 1911, the entire system was abandoned, and a hydroelectric plant built by the Cohoes Company supplied power. This did away with the hassle of maintaining the entire water system, including removing weeds and refuse from the canals and fixing bridges, etc. over the canals.

By 1836, the system was almost two lines long, with a total drop of 120 feet, which allowed for 6 levels. In 1840, the Erie was relocated so it could be enlarged, and the old section sold to the Cohoes Company. The major extent of the system was reached in 1880. After the 1911 conversion to electrical power, the canals served no real purpose, but only slowly were drained or filled in over the next half century or more.

The canals were four feet deep, trapezoidal in cross-section, and varied in length and depth. Some of the power canals, like most of the Erie Canal, had earth banks. In some sections, rectangular course limestone was used for the walls. An arch-shaped opening allowed water into the spillway. Some sections were connected by hollowed tree trunks some four to five feet in diameter. (The technology of the time did not permit for large iron pipes or corrugated culverts. Wood, if continually immersed, holds up pretty well to rotting. Even today ever so often we hear of a wood trunk failing in the local water system, but only more than a century later.

Despite the reuse of a section of the Erie Canal, a power canal system was different. A regular canal system was to float boats, so the cross-section could not fall below a certain minimum, and the reason it was exposed is obvious. A power canal system was simply a means to channel water to various locations, and today would have been accomplished by an underground pipe system, not an open shallow waterway. Normally a watercourse would be deeper and narrower to minimize the area in contact with the earth, a similar reason as to why a pipe is round. (A pipe or tank is round because a circle has the minimum ratio of perimeter to area. Under pressure, any other shape would tend to distort toward a circular shape.) The power canals were so shallow because every foot deeper was a foot shaved off the drop between levels.

The canals were part of the city's rectangular grid. Circular or squarish ponds could have been created at each level to act as a reservoir, but apparently that wasn't needed, and would have eaten up valuable real estate.

The mills powered by the canal system were long, tall, and narrow. As with other Victorian architecture, the height was held in check by available building technology of masonry, they were narrow as the sunlight, the only practical source at the time for lighting, could only reach in so far. Hence the only way they could get enough building volume was in length.

Number 3 building of the Harmony Mills complex was almost 1,100 feet long, making it perhaps the longest mill in the world. It was 75 feet wide and five stories high, the fifth being the usable attic under the Mansard roof. Power was developed via three Boyden-type turbines, geared together. Six leather belts distributed the power to the various floors, with the drive-shaft on each floor extending the entire length of the building. (This meant the building had to stay in line.)

Thus the power canals were shaped like their transportation counterparts, but for different reasons.

On The NEB&W

At that start of this layout, we were planning to use a double-track through truss bridge built for the last layout. As it had to go where we had double-track, which was only between Troy and Saratoga, it was to wind up in Cohoes. The scene was to be based on where the D&H crosses the Barge Canal in Waterford, with the lock gate in the background to hide where the water hit the backdrop. The Barge Canal bridge is only about half as long as our model bridge, so the scene was already compromised. The bridge was so long it seriously affected the rest of the Cohoes scene, leaving no room for any sufficient industries, so this idea and this bridge were abandoned.

The original Green Island Railroad Bridge was a covered bridge, with a 30-foot wide movable span at the Troy shore to clear the small watercraft going upstream. (Troy was founded at the head of navigation of the Hudson.) After the great fire of 1862 (started when a spark from a locomotive set the bridge on fire, which in turn burned down the rest of the city), the bridge was rebuilt in wood. In 1888, an iron or steel series of trusses replaced the covered bridge. The span nearest the shore was a swing truss, with the pivot on the shore itself, and half the bridge swung around on dry land.

As part of the canalization, the Green Island bridge was rebuilt. The swing span was replaced with a fixed span, and the next span, the one across the major section of the river, was made to lift by means of a tower added on both adjoining spans. This work was completed in 1925.

In our scene of Cohoes, we plan on modeling the Hope Knitting Mill, which had a power canal between it and the tracks.

Reference

  • Coal Boats To Tidewater - This book by Manville B. Wakefield covered the history of the D&H Canal. I don't know the publisher.



Howell-North

  • The Delaware & Hudson - The book by Jim Shaughnessy covered the history of the D&H transportation conglomerate, from its start as a canal system, along with its ownership of the steamship lines on Lake George and Champlain, and that of the local trolley systems. A good portion of book is devoted to the canal system, which used a combination of waterways and a gravity railroad to conquer the mountains of Pennsylvania. Order form for this book.]



Smithsonian Institution

  • A Report Of The Mohawk-Hudson Area Survey - This work, edited by Robert Vogel, is composed of studies and plans of various industrial artifacts. It was conducted by the Historic American Engineering Record (HAER), in fact, I believe this was the pioneering report.
    It contains studies of the Delaware Aqueduct at Lackawaxen, PA on the D&H Canal, the Schoharie Creek Aqueduct on the Erie Canal at Hunter, NY, the locks at Cohoes and Waterford, NY, on the Erie and Champlain Canals, and the power canals of Cohoes Company. Steingart Associates.