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operator's table; a metallic button, fig. 30, plays over their surface. This Fig. 30. button connects each brass stud with its opposite, and a change in its position changes the direction and channel of the current at pleasure. Thus, the intermediate operator wishes to break and close the "through circuit, (this is synonymous with main circuit,) he turns his button, bringing B in contact with D; the course of the current can be easily traced. But again, cutting off his left hand neighbor, he wishes to converse with his right, the button changed so as to connect A with C, the current passes directly to the ground through his instruments. Supposing a binding screw at S, the left or right hand wire may thus be brought in connexion with the ground. The buttons 1, 2, and 3, are simply used as convenient duplicate keys, or circuit closers, when the operator is re ceiving."

Fig. 31.

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When the line is found deranged at an intermediate office, by the evidence of a current unnaturally strong or weak, the impression is that the wire is broken at one or both sides of the office. Supposing the wire continuous from one end of the line to the other, and a battery at each, the current passes through the intermediate magnet without interruption, and the circuit established is termed a "through circuit." When a derangement is perceived, the intermediate operator alters the through circuit, and by connecting with the ground, makes two short circuits.

Several methods have been devised to obviate the disastrous consequences that sometimes result from violent electrical action during thunder storms, such as the melting or breaking of wires, total destruction of long distances of the circuit, injury to office furniture or the operators connected with it; among the most important of which are those that combine the readiest communication with the ground to convey away the superabundant fluid; one is to have the circuit closer of a receiving magnet, employed for this sole purpose, pass into the earth; another is the metallic connexion with the surface of a brass ball, surrounded by a ring situated in and forming part of the circuit, from the inner circumference of which minute metallic points project towards, but do not quite touch the ball; both of these, however, are inefficient at times.

Professor Morse, has deservedly received the highest approbations of the American people for the invention that not only calls forth wonder at its accomplishments, but has proved itself an invaluable agent in political economy. Excepting efficient and economical batteries, most of the discoveries in this department of science had been made, which were essential to a proper foundation of his invention; some hand was necessary to elicit the remaining facts, combine and give them a mechanical VOL. XXII.-THIRD SERIES.-No. 3.-SEPTEMBER, 1851.

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arrangement and application, and then to thrust it before a distrustful public, to solicit the attention and patronage of the government for the proper attestation of its merits.

It was novel to the American people; no one had projected the thing here successfully, though many had thought of, and some tried it; through Professor Morse's indefatigable perseverance, the adjuvant resources of science were united in the form of utility; though dependant for most of his information upon others, he had the confidence in its final success, to master opposing obstacles, and bring to his aid, those who had labored honorably and prosperously in the progress of knowledge.

To be Continued.

For the Journal of the Franklin Institute.

On P. V. Du Trembley's Combined Vapor Engine.

At the works of Messrs Stillman & Allen, New York, there is now in operation, one of Du Trembley's combined vapor engines, which is worthy of notice from its peculiar construction; but more particularly as it is claimed by the inventor, that 50 per cent. of the fuel used in the ordinary steam engine and boiler, will in the combined engine be saved; or, in other words, a given amount of fuel will do twice the work in the combined vapor engine, that it will in the ordinary steam engine, a result most devoutly to be wished, no matter how cheap fuel may become. A description of the engine is here given in the inventor's own language:

"This invention is applied either to a single engine, with two cylinders and pistons, or, as is usual for maritime purposes, two distinct engines, with a cylinder and piston each. In either case, one of the pistons is acted upon by steam, and the other by the vapor of perchloride, or of any other easily vaporized liquid, termed auxiliary liquid. The steam power is generated and applied as in the ordinary engine; but upon the escape of the steam from the first cylinder, after having exerted its expansive force therein, it passes into an air-tight case, termed a vaporizer, containing a number of small tubes charged with perchloride, or some easily vaporized liquid, penetrates into the space between, and comes in contact with the entire surface of the tubes. The faculty of absorbing caloric, possessed by liquids of the before mentioned class, is so powerful, that immediately upon the steam coming in contact with the surface of the tubes charged therewith, a large portion of the caloric of the steam is absorbed by the liquid in the tubes, which becomes thereby vaporized, and the steam being thus deprived of its caloric, is immediately condensed and is then returned into the steam boiler. The vapor thus obtained by the action of the steam, or perchloride, or other liquid in the tubes, termed auxiliary vapor, is conducted into the second cylinder, and after exerting its elastic force (which is greater than steam) upon the piston in the second cylinder, is condensed, and by means of a force pump is returned into the vaporizer, which it thus keeps regularly supplied, and is alternately vaporized and condensed. The saving effected by this engine is in the small quantity of coals required for the steam, the smaller room occupied by it, and the avoidance of incrustation in the boiler, the water being completely distilled by the reiteration, vaporization, and condensation. The perchloride is a very cheap fluid; when once charged, the quantity in the tubes will last a considerable time, the alternate condensation and vaporization occasioning a very trifling loss in the bulk or quantity employed. Every liquid boiling at a low temperature can be used. The best, according to the trials, are sulphuric ether, sulphur of carbon, chloroform, chloride of carbon; the first two are inflammable, the last two are not."

Without discussing the practical merits of the invention, I should like to enquire if the same economic result could not be produced by using the easily vaporized liquid directly in the boiler itself. Second, what evil result (if any) would be produced by the oil, which has occasionally

to be used in every working cylinder. In long voyages, this oil in the aggregate, amounts to a large quantity, and some means are absolutely necessary to get rid of it. Will not the mixture of oil with the easily vaporized liquid change in some way its nature? I hope that Mr. Du Trembley has accomplished all he states, and that his engine will prove FULTON. something more than a model.

For the Journal of the Franklin Institute.

Passage of the Steamer Baltic from Liverpool.

The Quickest Trip on Record, has been made by the steamer Baltic of the Collins line of steamers. She left Liverpool at 4 o'clock P. M., on Wednesday the 6th of August, and passed the battery at New York, at 20 minutes past 6, on Saturday morning the 16th. Apparent time 9 days, 14 hours, 20 minutes. Actual time 9 days, 18 hours, 45 minutes. She had good weather and fair winds for the greater part of the passage, and her daily run was as follows:

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On the arrival of the Baltic, the engineers of the Pacific presented to the engineers of the Baltic, the wreath of championship which they had received at the time they made their quick trip, it being well understood. that the one who makes the quickest trip, is to have the custody of the said wreath, and is of course, by right, the champion of the line, to say nothing of the Cunard steamers, which are now allowed to arrive and depart without note, so far as speed is concerned.

H.

For the Journal of the Franklin Institute.

Lake Steamer Buckeye State.

This vessel, recently added to our lake flect, has some peculiar features in her machinery, which render her worthy of special note. She has one of Smith & Baird's compound expansion annular beam engines, being the first of the kind applied to any steamer in this or any country; the whole has been arranged by Erastus W. Smith, Esq., engineer, of New York City, and is a good specimen of engineering. The peculiar feature of this engine, is the employment of two cylinders, one being situated within the other, both having the same stroke of piston. The small cylinder has a diameter of 37 inches, and a stroke of 11 feet, and into it the steam from the boiler of 40 lbs. average pressure is admitted, by a set of double balance valves, of the usual form. The larger cylinder surrounds the inner one, its diameter is 80 inches. The space between the two

forms an annular chamber, and the large piston has two rods, and is packed on its inner and outer circumference; with this exception, the engine is of the usual form; but the advantage of admitting steam of high pressure, full stroke, or nearly so, on to the piston of the small cylinder, and expanding it into the large cylinder, must be apparent, as the great shock caused by the admission of steam of high pressure on to the area of a large piston, is almost entirely got rid of, and the method of expansion is inore efficient. The following are some of the dimensions of the Buckeye State:

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Consumption of Bituminous Coal per hour, 3158 While the Mayflower, a boat of about the same size and speed, consumes 6160 lbs per hour, showing a decided saving of fuel. She has three boilers with square fronts, 9 feet wide, and round shells 9 feet diameter, and in length 17 feet 9 inches. Each boiler has but one furnace, 8 feet wide, with grates 6 feet 6 inches long, with two lower flues of 20 inches diameter, and one of 26 inches; the return to the chimney, which is in front, is through 190 tubes of 3 inches internal diameter, which tubes rise 4 inches at the front end; whole number of tubes 570; diameter of chimney 6 feet; height above grate, 65 feet; draft natural, and steam abundant; no trouble has yet been experienced from the great length of tube. It would be desirable to know the temperature in the chimney, as it is possible that the tubes may be longer than is necessary, as it has generally been supposed that very long tubes gave no additional evaporating power. This question is an important one, and I shall have it examined into, and will report at some future time,

X.

Recent Improvements in Photography. By ROBERT HUNT.* With the advance of this beautiful art there appears to be a progressively increasing desire to produce more artistic results; and numerous manipulatory improvements have recently been introduced, many of them with the most decided advantage. It is thought desirable, therefore, to devote a short space to the description and consideration of such of these as are the most important.

The use of collodion promises to be of exceeding importance. Collodion is a peculiar preparation, formed by dissolving gun-cotton in ether; it is a very mucilaginous solution, of a volatile character, and the ether evaporating, leaves a film of the utmost transparency behind. It is not all kinds of gun-cotton which dissolve equally well in ether; the most easily soluble is prepared by soaking good cotton in a saturated solution. of nitrate of potash for some time: it is then, in a moist state, plunged into • From the London Art Journal for July, 1851.

sulphuric acid, with which but a small quantity of nitric acid has been mixed. After remaining in the acid for about a minute, it is well washed with water, until no trace of an acid taste is discovered, and then dried at a temperature but very slightly elevated above that of the apartment.

Having obtained the collodion, the mode of proceeding best adapted for insuring success appears to be the following:

Iodide of silver is precipitated from a solution of the nitrate of silver by adding iodide of potassium to it, the yellow precipitate being well washed so as to remove every trace of nitrate of potash; it is then dissolved in a saturated solution of the iodide of potassium. This mixture is added in small quantities to the collodion, and the whole well agitated; by this means we obtain a combination of this peculiar substance with iodide of silver and potassium. Mr. Archer, who has devoted. considerable attention to this preparation, prepares what he calls a collodoiodide of silver, whether in the above manner we are not certain. Mr. Archer's preparation is exceedingly sensitive, but the above is believed to be equally so. To use it, no other manipulation is necessary than to pour the mixture over a glass plate held upon the hand, moving the glass to and fro, to ensure the complete coating of every part; the fluid is poured off by one of the corners, and the film which adheres to the glass dries almost immediately. This is then washed over with the gallo-nitrate of silver, in the same manner as on the albuminised glass plates, and it is ready for the camera. Where the proportions have been happily hit upon, the result is the production of a picture almost instantaneously. Very fine portraits are obtainable in about ten seconds in diffused light; the image is developed in the same manner as in the calotype process, by the use of the gallo-nitrate of silver, and fixed by means of the hyposulphite of soda.

By the kindness of Mr. Horne we are enabled to add the following mode of operating. Mr. Horne has been so successful an operator with the collodion that we print his communication entire, that no part of his instructions may be lost:

"The first article is the collodion, and most persons are aware that this is a solution of gun-cotton in ether, but, for the purpose now under consideration, should contain a small quantity of iodide of silver dissolved in excess of iodide of potassium. It should be sufficiently limpid to run freely over a plate when poured on, or ether must be added until this result is obtained. If the collodion is too thick, great difficulty will be experienced in obtaining an even coating; but when of a proper consistence, plates of any size may be readily coated.

"The plan which I have adopted, and with great success, is as follows:-Take a piece of flat glass cut to the size of frame, and, having washed it with water, and wiped the same quite dry, then, either, by holding at one corner, or if large, placing it on a levelling-stand, pour on the centre of the plate a good body of liquid which will readily dif fuse itself equally over the surface. Immediately pour the liquid off again into the bottle from one corner; and by bringing the hand holding the plate down a little, that the liquid may run to the lower edge, and drawing the mouth of the bottle along, those lines first formed will run

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