It appears necessary to give the reader some idea of the principles of the steam engine which is to produce such novel and strange effects; and this I will endeavour to do in as few words as I can, by shewing the extent to which the principles are applied already.

To make a steam as irresistible, or powerful as gunpowder, we have only to confine and increase the heat by fuel to the boiler. A steam engine with a working cylinder only nine inches in diameter, and a stroke of the piston three feet, will exert a power sufficient to lift from 3,000 to 10,000 pounds perpendicularly, two and a half miles per hour. hour. This This power applied to propel a carriage on level roads or rail-ways, would drive a very great weight with much velocity, before the friction of the axletree or resistance of the atmosphere would balance it.

This is not speculative theory. The principles are now in practice, driving a saw-mill at Manchacks on the Mississippi; two at Natchez, one of which is capable of sawing 5000 feet of boards in 12 hours; a mill at Pittsburgh, able to grind 20 bushels of grain per hour; one at Marietta of equal powers; one at Lexington, (Ky.) of the same powers; one a paper-mill, of the same; one of one fourth the power at Pittsburgh: one at the same place of 3 times the power, for the forge, and for rolling and splitting sheet iron; one of the power of 24 horses at Middletown, (Con.) driving the machinery of a cloth manufactory; two at Philadelphia of the power of five or six horses, and many making for different purposes; the principles applying to all purposes where power is wanted. OLIVER EVANS.

Ellicott's Mills on the Patapsco,

Νου. 13, 112.

A new fire engine.—Make a small engine of tin and leather, to contain one cubit foot, or 6 gallons of water, which weighs 62; lbs. with a piston to project the water

through a pipe to be guided by the hand. This may be carried by a man on his breast, hung by straps round his neck and must have two stirrups pending from the lower end of the piston rod.

Fifty men thus equipped, who would on an alarm, proceed immediately to the fire, and on their way fill their engines and ascend to the roof, or upper loft, or as the case may be, to come near the fire; then by stooping and pute ting their feet in the stirrups, and straightening themselves, they might exert such force as to eject the water thirty feet, horizontally, or fifteen feet perpendicularly, to strike the burning materials. Three hundred gallons of water, carly applied and so immediately powerful to the spot wanting it, would extinguish most fires before the great engines could get into play. But the great engines must be preserved, and used on other occasions.

O. E.

Extract from the (Philadelphia) Democratic Press of January 28, 1813.

"An experiment was lately made in Charles River, near Boston, to shew the velocity of a steam boat, constructed for the conveyance of passengers, &c. in the Middlesex canal. The boat was driven seven miles and six furlongs in sixty minutes; and there is no doubt by the best informed that it will go nine miles."

The steam engine in the said boat was constructed by Oliver Evans, on his improved principles adapted to the purpose of propelling boats and land carriages; and which he is convinced, will propel boats ten miles and upwards per hour, through still water.

The improvements made by Mr. Watt, may be sum. med up thus,

1st. Condensing the steam in a vessel separate and at a distance from the cylinder, which is now no longer Vol. II.

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cooled by the injection water, as in Newcomen's or the atmospheric engine.

2dly. Making an approach to a vacuum by pumping out the air, which always, to a certain degree, accompanies the steam, and by its elasticity re-acts against the under side of the piston.

3dly. Keeping the outside of the cylinder in which the piston works, hot, by the intervention of steam between it and a casing.

4thly. The parallel motion of the beam, by which the stiff upwright rod attached to the beam and the piston presents its perpendicularity during the stroke.

5thly. Depressing the piston by steam instead of the atmosphere.

6thly. Keeping the top of the piston hot by the casing between the piston and the outward air, so that the steam let on above, is of the same temperature always as that below.

7thly. Consuming the smoke of the fuel, by making it pass through and over the red-hot coals.

8thly. Supplying the boiler with the hot injection

water.

9thly. The application of the steam pipe above the water in the boiler, to ascertain when the water is too high: and the mode of opening the valve of the feeder, when the water sinks too low in the boiler; by the floating stone instead of the ball-cock.

10thly. The circular motion communicated to the fly wheel by means of the sun and planet wheels.

Mr. Cartwright's improvements consist in

1st. The method of giving the necessary perpendicu lar motion to the piston rod.

2dly. The condensing the steam by expanding it in a thin surface between metal balls cooled with water inside and outside, so that a great surface of steam is exposed

to the action of cold, in the manner as a great surface of air is admitted to the wick of Argand's lamp.

3dly. The accurate fitting of the metal piston to the cylinder by means of springs, which saves much trouble and expence in packing.

4thly. As all the steam is brought back into the boiler, it enables us to use ardent spirits, if necessary.

An account and drawing of Cartwright's engine may be seen in 1 Tilloch's Phil. Mag. 1.

I do not find, however, that Cartwright's engines are much in use.

Mr. Hornblower's improvements do not seem to consist in the adaption of any new principle, for reasons stated by professor Robison, in the article steam engine, in the Edinburgh Encyclopedia, p. 771, but in the methods used to make his collars air tight, in the structure of his condensing vessel, and the framing of his beam. A plate of Hornblower's engine is given by professor Robison in that article, and by Dr. Gregory in the 2nd vol. of his mechanics.

in

The improvements introduced by Mr. Woolf consist

1st. His ascertaining the law of the expansion of steam, by a volume for each pound per square inch on the safety-valve: hence

2dly. In his using steam at much higher temperature than in the common engine: and

3dly. In his using it twice over in separate cylinders; though this idea seems to have occurred also to Mr. Hornblower.

4thly. In applying heat to the hot steam in the second cylinder and using as the metalline substances as the mean of communicating and preserving heat to the steam. 5thly. In the form of his boilers, of which I shall give

a drawing in my next number, as I apprehend it is a great improvement on the common form.

But there is some similarity to Mr. Woolf's ideas in the patents of Mr. Sadler and Mr. Trevethick, as will appear from the description of his engine in the second volume of Nicholson's Journal, quto. series, p. 231.

Mr. Sadler's improvements consist in

1st. His working without a lever or beam.

2dly. Part of the steam previous to condensation, is employed a second time in another cylinder, the piston of which is depressed by the atmosphere. By this second application, it performs the office of an air pump, and adds to the total force of the machine.

Mr. Trevethick's engine worked by the force of a column of water inclosed in a pipe, may be understood from the description of it in 1 Nicholson's Journal, 8vo. p. 161. But his steam engine appears to be worked by steam of very high temperature, which is not condensed but permitted to escape.

The article "Steam Engine," to be concluded in the

next.

INSRUCTIONS FOR PARENTS.

BY CH. GOTTH. SALZMANN.

1. How to make yourself hated by your children.— Treat them with injustice, their hatred will naturally follow. Or this purpose may be effected by one parent's setting the children against the other.' Mr. S. here instances the very common practice of mothers threatening children with being punished by their father, or condoling with them when their father has corrected them. Be insensibie to the caresses of your children, or take no share