paper that the expansive force of the explosion might also be employed; but his machine was not founded on this principle.

3. Clymer's Improved Ploughs.

Our readers are no doubt aware, that two methods have already been published for forming the mouldboards of ploughs, the one by Mr. Amos, in the Transactions of the Agricultural Society, and the other by Mr. Jefferson, which has been published in the Philosophical Magazine, and in the Edinburgh Encyclopædia, article AGRICULTURE. Mr. Clymer, however, seems to have improved upon these methods, and to have produced a mouldboard which turns the furrow with less friction and resistance than any other plough, the force exerted in pressing laterally and in lifting the clod being equally divided.

Mr. Clymer forms two mouldboards, one to be used on light land, and the other on stiff or wet land; but the geometrical rules are too long to be given here; so that we must refer the reader to Newton's Journal of the Arts, No. XL. p. 170.

Another of Mr. Clymer's improvements consists in a new construction of the beam and its appendages, by means of which the draught of the plough may be adjusted to produce any required depth and width of furrow, and also to suit a single or a double team.

4. Hydro-Pneumatic Lamp.

The discovery of M. Dobereiner of the remarkable action of Spungy Platinum upon Hydrogen Gas, has led to the construction of an elegant lamp for producing instantaneous light.

This lamp was, we believe, first made for sale by Mr. Garden of London; but it has since been constructed in an improved form by Mr. Adie, Optician in this city.

The form given to the lamp by Mr. Garden is shown in Plate I. Fig. 3, where AB is a glass globe fitting tightly by a ground shoulder into the neck m n, of another globe or vessel CD. The globe AB terminates downwards in a hollow neck, m n o p, in the lower end of which is placed a small cylinder of zinc o p. Into the neck of the vessel CD is fitted a brass piece, a b c, through which the gas contained in CD can escape at the point c, by turning a cock d. An arm e ƒ slides through h, and carries in a brass box P a piece of the spungy platinum, which can be brought nearer to c, or removed from it by sliding the arm eƒ through h.

If we now pour diluted sulphuric acid into the vessel AB by the mouth at S, it will descend through the neck m n, compressing the air in CD if the cock d is shut. The diluted acid will now act upon the ring of platinum, o p, and produce hydrogen gas, which after the common air in CD is let off, will gradually fill the vessel CD. When the gas is thus collected in the vessel CD, a stream of it may at any time be discharged through the aperture c, and thrown upon the spungy platinum P, when it will produce such an intense heat as to make the platinum red hot, and thus afford an instantaneous light.

"In Mr. Garden's lamp, the ring of zinc op floats upon a piece of cork, so that when the vessel CD is filled with gas, the dilute acid does not touch the zinc, and consequently no more hydrogen is produced; but the moment any of the gas is let off at c, the pressure of the head of fluid in AB overcomes the elasticity of the remaining gas in CD, and the diluted acid is forced up to the zinc, to reproduce the wasted hydrogen. - By this ingenious contrivance, the diluted acid is pressed up against the zinc when more hydrogen is wanted, and withdrawn from it when the vessel CD is full.

The form given to the lamp, by Mr. Adie of this city, is shown in Fig. 4, where the different parts are marked by the same letters as in Fig 3. In this construction, a cone of glass k formed on the bottom of the vessel AB is made to hold the ring of zinc, op, which remains permanently in that position. This lamp has the advantage of greater stability, and is less liable than the other to be deranged by an accidental cause.

Professor Cumming of Cambridge, who constructed one of these lamps in December 1823, found it necessary to cover up the platina with a test tube, or a cap, after every experiment. With platina foily of an inch in thickness, and kept in a close tube, he produced the same effect; but when the thickness of the foil was it was necessary to raise it previously to a red heat.

These lamps, besides their extreme beauty as philosophical toys, are of great use in counting houses, as well as in private houses, in summer, when there is no fire at which a taper can be lighted.

5. White's Floating Breakwater.

Among the practical and useful inventions of the present day, the floating breakwater of Mr. White, for which he has received a patent, promises to hold a respectable place.

This contrivance consists of a series of square frames of timber, connected by mooring chains, or cables, attached to anchors or blocks; they are disposed so as to enclose either a rectilineal or a curvilineal space for the reception of ships, which may ride there, protected from the breaking of the sea or surf.

These frames consist of logs of Quebec yellow pine, from thirty to fifty feet long, and from eighteen to twenty inches thick. The logs are bolted together so as to form a square frame, consisting of two parallel frames. The separate frames are connected by ropes or chain cables, secured to anchors or mooring blocks. The height of these frames may be increased by logs or pieces of timber on the tops of the frames, not exceeding five tiers in a vertical position, for the purpose of breaking the waves more completely in places where the water is violently agitated.

The advantages of this breakwater have been actually experienced at Deal, and certified by some respectable persons of that place.

The inventor recommends it particularly for fishing coasts, where the surge often prevents boats from putting off and landing; and also for bathing places, where it will always produce smooth water, and protect VOL. I. NO 1. JULY 1824.

L

the machines. A drawing and more minute description of this invention will be found in Newton's London Journal of Arts, &c. vol. vii. p. 232.

6. Perkins's Steam Engine.

We understand that Mr. Perkins has at last completed his apparatus, so as to demonstrate to a select party of friends the power of his engine, by lifting a given volume of water through a certain height. The particulars of the experiment, with which we are not yet acquainted, will, we have no doubt, be communicated to us before the appearance of our next number. *

The history of this great invention, which Mr. Perkins has published for the use of his friends, exhibits an interesting picture of the progress of discovery in a mind capable of availing itself of those facts and views which accident and speculation frequently present to it. The tremendous explosions which often take place in iron foundries when a drop of water has got into the mould, and other facts, convinced Mr. Perkins that water confined by pressure until it became sufficiently charged with heat, was capable of exerting a force almost incalculable. The interest excited in England by steam engines, turned his attention particularly to their construction. In his earliest speculations he was convinced that much heat was lost, in consequence of a sheet of steam being sometimes formed at the bottom of the boiler, at the commencement of ebullition. In this case the bottom becomes red hot, and the heat escapes by radiation, in place of being given off to the water. Hence Mr. Perkins was led to the idea of compressing the water in a close vessel with high pressure, in order to prevent ebullition, and compel the water to take up the heat.

In the ordinary condensing apparatus, where 1170 degrees of heat are absorbed in generating the steam, 1070 are lost by entering into the condensing water. Mr. Perkins, however, has contrived, after much labour, a method by which nearly all the heat has been absorbed from the steam, and returned to the generator.

The next object of Mr. Perkins was to save the heat that was lost in the common mode of supplying the furnace with air. In order to prevent the escape of the heat up the chimney, Mr. Perkins forces the air in at the top of the furnace. The effect of this is also to consume the smoke, which, in steam vessels, is a matter of considerable importance. In order to give an idea of the force of steam, and the saving of fuel, when it is raised under high pressure, Mr. Perkins makes the following observations.

"It is a well-known fact, that water does not boil under atmospheric pressure until it has been heated to 212°, after which all the heat that can be applied cannot increase the temperature of the steam or water. Now, add an artificial atmosphere by loading the escape valve (the surface of which is equal to a square inch) with 14 lbs. and it will receive

It has been stated to us, that Mr. Perkins has received the sum of L.36,000, from an enterprising individual, for a share of his patent.

250° of heat with a very little addition of fuel, and the pressure on the square inch will be doubled, or 28 lbs.; the mechanical action will not be double, yet it will be increased much more than the consumption of fuel. Let the valve be loaded with two addi additional atmospheres, or 42 lbs. and the temperature will be raised to 280°, and will again produce double pressure, or 56 lbs. in the inch, and so on. If the generator be made strong enough, as I have no doubt it may be, to withstand 60,000 lbs. load on the escape valve, the water would not boil, although it would exert an expansive force equal to 56,000 lbs. on the inch, and be at about 1170 degrees of heat, or cherry red. Water thus heated would, if it were allowed, expand itself into atmospheric steam, without receiving any additional heat from what surrounded it. It is not, however, necessary to heat the water to more than about 500° to have it flash into steam, if the generator be properly constructed."

Mr. Perkins's engine, as drawn under his own eye, is shown in Plate VIII. Fig. 1, where AA is the generator, now made of one piece of wrought iron, and placed in the furnace FFFF. The induction pipe BBB at its entrance into the generator is closed with a valve loaded with a variable weight L, and rising obliquely, terminates in a rotatory valve MM, which opens alternately a communication between the upper end of the induction pipe and the upper or under sides of the piston, which moves horizontally in the cylinder or pump KK. The arm NN fixed to the extremity of the piston, gives motion to the fly wheel OOO, which maintains the rotatory motion of the valve M. The eduction pipe G passes from the valve M through the condenser and collector of heat HH along CCC uu to the reservoir E filled with water under simple atmospheric pressure. The condenser HH is a cylinder of copper about 20 feet long and four inches interior diameter, from the bottom of which proceeds a pipe DD connected with the pump PP, whose piston is raised by the lever and variable weight R, at the end of which is a chain QQQ, by means of which it is wrought by the arm NN.

A tube I, I, I, I descends from the upper end of HH, and after forming several spiral turns round the bottom of the furnace F, it rises to the valve V, which opens upwards and downwards, and is turned with a variable weight W, with 50 atmospheres, or 700 lbs. on the square inch. From V the tube I I is continued to within an inch of the bottom of the generator A, as shown by the dotted line.

A tube SS proceeds from the top of the generator to the dial U which shows the number of atmospheres with which the machine works, and at the part T of the tube SS is the safety valve of copper, which is torn up when the pressure exceeds greatly the ordinary one. There is a small

apparatus at Y, to furnish oil to the piston rod. The two tubes with stop cocks at X X allow the atmospheric air to escape from the spaces above and below the piston. The parallel motion apparatus, which is not shown in the figure, is fixed to the pillar Z.

The generator being now filled with water, up to the valve at B, water is also poured in at V, so as to descend into the pipe I, I, I, and flow

into the generator till it is filled up to the valve. By working the pump P, water is driven by the pipe DD, into the condenser HH, which is filled to the top, the water redescending by the tube I,I,I, which it fills, and also the spiral of the ascending branch, till the compressed water, arriving at the valve V, shut by the weight W, opens the valve, and joins the rest of the water in V, I, I, I. It is almost unnecessary to say, that the cylinder K, the induction pipe BB, and the eduction pipe CC, which passes through the condenser, are empty. The induction pipe being now supposed to communicate with one of the sides of the piston, let the furnace be lighted. The heat will then rise through the water, and expand it, till it is nearly able to overcome the weight L. At this time the pump P is made to act so as to introduce a given quantity of water into the generator at its bottom. In forcing in this water, the force raises the valve, and a quantity of water equal to that admitted enters the induction pipe at B, and instantly flashing into steam, acts upon the piston, and drives it to one end of the cylinder. The eduction pipe being opened at this time, the steam, after having acted upon the piston, passes through the collector and condenser HH, giving out its heat to the water in HH, and passing, in a cold state, through CC to the reservoir E, from which it is re-pumped for use through the tube D. The motion of the piston having turned the fly-wheel, enables the rotatory valve M, which is put in motion by the fly, to shut the communication between the first side of the piston, and open a communication with the other side; so that when a fresh quantity of water is forced into the generator, and a fresh quantity of steam flashed out of it, the piston is drawn back to its first position, and so on, a continued motion being thus kept up. The reader is no doubt aware that the water in the tube D coming from the pump P, and also the water in the condenser HH and the tube I I, is compressed with a weight equal to that exerted by W on the valve V. See the Bibliothèque Universelle, from which the drawing is taken, and the preceding description abridged, the original being drawn up by Mr. Gibbons Spilsbury, a friend of Mr. Perkins.

Mr. Perkins is, we learn, busily employed in fitting out a steam boat, with one of his engines, to go to Calcutta by the Cape of Good Hope. A steam boat from the Thames entering the Ganges will complete the triumph of this distinguished mechanician.

7. M. Bracconnot's Process for making the Schweinfurt Green Dye. THIS green dye, which has acquired great reputation, and the secret of making which was known only to a manufacturer at Schweinfurt, hás been analyzed by M. H. Bracconnot. He found it to consist of arsenical acid, deutoxide of hydrated copper, and acetic acid; thus approaching, in its ingredients, to Scheele's Green. After much difficulty, he succeeded in finding the following method of recombining these materials:

1. Dissolve six parts of sulphate of copper in a small quantity of warm water.