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ARTICLE XII.

DIRECTIONS FOR WORKING A STEAM ENGINE ON

THE NEW PRINCIPLE.

It has been shown that a vacuum will probably receive and contain a greater quantity of heat in a latent state than a plenum, (see article 4): and it is evident that the piston of an engine leaves a perfect vacuum behind it in the cylinder at every stroke, which is to be filled with latent heat from the fire, besides active heat to give power to the steam to carry its load; now it appears plain, that if the engine be started before the steam has acquired a sufficient power, and let it move briskly with the load it is'able to carry, that the piston will create vacua so fast, as to carry off all the heat of the fire, as fast as generated, to supply the latent heat to fill the vacuum: it will therefore be very difficult to use the power of the steam to its proper degree, and thus fuel may be consumed without producing the desired effect. To save the fuel retain and confine the steam in the boiler until the power is raised to a greater degree than is sufficient to carry the load, which will be shown by the lifting of the safety valve with the weight farther from the centre than it is commonly hung; then start the engine, and the power will be reduced to its proper degree before the cylinder becomes hot; take care that the engine does not dart with too quick a motion, and it will carry off less heat in a latent state at every stroke, but more in an active state, producing power in the steam to carry its load, and the engine will work on, if the fire be kept up, and produce great effects.

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If propelling a boat against the Mississippi, fix the valve to shut off quick, say at 1/6 or 1/4 part of the stroke, when in an eddy or slow current; let the supply pump work to fill the boiler, and augment by these means the elastic power of the steam so as to be ready to lift the safety valve with a double load by the time you arrive at the strongest current; to ascend which alter the valve to shut off at 1/2 the stroke, and stop the supply pump until you have passed the rapid, (see article 8,) and the power of the engine will be quadrupled, which may be kept up by increasing the fire until you surmount the difficulty: you may regulate the power by closing and opening the throttle valve to let more or less steam out of the boiler into the cylinder; but there will be a great loss of power this way, because it would be working with weak steam in the cylinder while you have strong in the boiler, and returning to the old exploded principle.

If propelling a land carriage, on turnpike roads, while on level or descending ground, gear the wheels to move fora~rd quickly, and fill the boiler, reserving the steam, as above stated; so as to quadruple the

power of the engine by the time you arrive at the foot of a hill; then alter the gears to move the carriage with

or 1/2 velocity, as the ascent may require, and you ascend with 8 or 16 times the power, with 21 or 1/4 velocity, which enables you to ascend any hill on which the wheels will not slide. If the driver of a 5 horse waggon could have at his command 75 more to hitch on to help him, he would easily ascend hills. At all steady work, such as grinding, sawing, &c. fix the valves to shut off so as to keep up the power in the boiler and you will

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produce much greater effects from the same consumption of fuel, (see article 4.)

These principles have been proven as follows:

I constructed for the Board of Health of Philadelphia a machine for cleaning docks, called the Orukter Amphibilos or Amphibious Digger. It consisted of a heavy flat bottomed boat, 30 feet long and 12 feet broad, with a chain of buckets to bring up the mud, and hooks to clear away sticks, stones, and other obstacles. These buckets are wrought by a small steam engine set in the boat, the cylinder of which is 5 inches diameter and the length of stroke 19 inches. This machine was constructed at my shop, 1 1/2 miles from the river Schuylkill where she was launched. She sunk 19 inches, displacing 551 cubic feet of water, which at 62.5 pounds, the weight of a cubic foot, gives the weight of the boat 34,437 pounds, which divided by 213, the weight of a barrel of flour, gives the weight of 161 barrels of flour that the boat and engine is equal to. Add to this the heavy pieces of timber and wheels used in transporting her, and the number of persons genelally in her, will make the whole burden equal to at least 200 barrels of flour. Yet this small engine moved so great a burden, with a gentle motion up Market.street and around the Centre Square; and we concluded from the experiment, that the engine was able to rise any ascent allowed by law on turnpike roads, which is not more than 4 degrees.

When she was launched we fixed a simple wheel at her stern to propel her through the water by the engine. Although she is square at each end and fully constructed for sailing, (excepting that she is turned up short at

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bottom) and drew 19 inches water, yet we concluded diat if the power had been applied to give the paddle wheel the proper motion we could have stemmed the tide of the Delaware. It has been ascertained by accurate experiments,* that a boat formed to the proper angle at her bow and stern, will pass much easier through the water than one formed as this was; and that the increase of length does not sensibly increase the resistance: we may therefore safely conclude, that an engine 4 times as powefful would propel a boat 16 feet wide, 90 feet long drawing 2 feet water, the weight of which would be 86 tons, equal to 903 barrels of flour, about 7 or 8 miles an hour through the water, every thing being properly and well constructed. This force would be sufficient to propel the like burden against the stream of the Mississippi at the rate of 4 miles an hour. Considering the temporary manner in which the works were constructed for this experiment of propelling the Orukter both by land and water; the great friction there was to be overcome, and the disproportion of the load to the engine, there cannot remain any doubt but that a steam carriage may be constructed to carry 100 barrels of flour 50 miles in 24 hours, on any well made and well regulated turnpike road; and when every thing is properly arranged for supplying the machine with water and fuel at proper stages, one such carriage will clear as much net profit as 10 five horse waggons. Conceiving that those who are proprietors of turnpike roads are the only persons

*See the American edition of the Encyclopedia, vol. xvi. art. "Resistance."

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whose interest directs them to engage in the enterprise, I made the following statement, to be laid before the managers of the Philadelphia and Lancaster Turnpike Company.

TO THE LANCASTER TURNPIKE ROAD COMPANY:

GENTLEMEN,

PERMIT me to lay before your respectable body the following statement.

I conceive that carriages may be constructed, to be propelled by the power of steam engines which I have invented, to transport merchandise and produce from Philadelphia to Columbia, and from thence to Philadelphia, much cheaper than can be done by the use of cattle.

	Dolls
The enigne I estimate at	1500
The carriage	500
Say for unforseen expenses	500
Total	2500

This carriage I allow to carry 100 barrels of flour, and to travel 3 miles per hour on level roads, and 1 mile per hour up and down hills; say about 40 miles per 24 hours; making a trip from Columbia to Philadelphia in 2 days.

It requires 5 horse waggons, of S horses each, to transport 100 barrels the same distance in 3 days. The expense I estimate as follows:

	Dolls
5 Horse waggons at the cheapest rate, 100 dolls. each	500
25 horses at 100 dolls. each	2500
Gears for 25 horses at 7.75 dolls.	193.75
5 waggon covers at 7 dolls.	35
30 bags for feed at 1 doll.	30
5 jack screws at 6 dolls.	30
5 whips at 75 cents	3.75
5 feed troughs at 2 dolls.	10
5 grease cans at 33 cents	1.65
	3304.15
Expense of the steam waggon	2500
	2500
First cost in favour of the steam wagon, exclusive of the drivers	804.15
The steam waggon will perform the journey in two days, and carry 100 barrels of flour at 1 doll. 25 cents	125
The expense of fuel, 20 bushels of coals per 24 hours, 40 bushels at 37 1/2 cents, or wood equal thereto	15
3 men at 1 doll. per day for 2 days	6
	21
Profits of the steam waggon per journey, or 52 dollars per day	104
The horse waggons will perform the journey in three days and carry 100 barrels at 1 doll. 25 cents	125
The expense of feed for 25 horses at 33 1/3 cents per day, 3 days	25
5 men drivers at 1 doll.	15
	40
Profits on 1 journey, 85 dolls. which is 28 dolls. 33 cents per day	85

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The expenses of repairs, of horses, waggons, and gears of each horse waggon will be fully equal to the repairs of the steam waggon.

	Dolls
From the profits of the steam waggon per day	52
Deduct for repairs	2
Nett profit of the steam waggon per day	50
From the profits of the 5 horse waggons per day	28.33
Deduct for each 2 dolls.	10
Nett profit of all the 5 horse waggons per day, or 3.66 dolls. each per day	18.33

Add to all this that the steam waggon consumes nothing while standing, will roll and mend the roads, while the horse waggons will cut them up.

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Upon the whole it appears that no competition could exist betwween the two. The steam waggons would take all the business on the turnpike roads.

I have no doubt but you will duly appreciate the importance of such an improvement, and conceive it to be your interest to appropriate the sum necessary to put it in operation. I have invented the only engine that will answer that great purpose, as well as many others for which power may be wanted.

It is too much for an individual to put in operation every improvement which he may be able to conceive and invent.

I have no doubt but that my engines will propel boats against the current of the Mississippi, and waggons on turnpike roads with great profit. I now call upon those whose interest it is to carry this invention into effect. All which I respectfully submit to your consideration.

Gentleman,

Your obedient humble servant,

OLIVER EVANS.

Philadelphia, Sept.

26th, 1804

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