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tain some glimpses into the nature of those causes which have induced, and are now apparently inducing, those changes in respect to the aspect of his rings, which have, more especially of late, attracted so much attention. If Saturn also be so hot, that his future ocean is supended as a vast vapor envelope around him, it is possible, I conceive, that some portion of this vapor may migrate, by reason of the peculiar electrical conditions which it is probable his rings may be in, in respect to the body of the planet; and that such migration of vapor in an intensely frozen state, as it must be in such situation, may not only appear from time to time, as the present phantom ring does, but also incrust the inner portion of the interior old ring with such rast coatings of hoar-frost as to cause the remarkable whiteness which so peculiarly distinguishes that portion of his rings. In fact, such are the extraordinary phenomena presented by this planet, that one is led to hazard a conjecture or two on the subject; and, I trust, such as I have now the pleasure to offer may meet with a kind reception from the Royal Astronomical Society. January 13th, 1853."

For the Journal of the Franklin Institute. Description of a Portable Gas Apparatus, patented by STRATTON & BRO

THER, Philadelphia, Pennsylvania. Our improvement consists in constructing a stove, retort, and cooler, all arranged so as to be portable in the strict sense of the term, which may be used for the manufacture of illuminating gas from rosin or other suitable material.

The stove is constructed of any desired size; but differs from others, in having the front and back end plates cast in two pieces, so as readily to admit the retort to be placed in a suitable opening, and a portion we term a gate afterwards inserted above the retort. By our mode of balancing the retort on the furnace or stove ends, the projecting ends and heads of the retort counterbalance the weight of the centre thereof, which heretofore has destroyed other apparatus by their sinking in the middle when softened by the requisite heat to eliminate the gas profitably; there being also no connexion between the retort and the stove, there is no destruction of the latter from the expansion and contraction of the retort. By the form of the stove, and use of the additional section, damper, &c., there is great control and advantage in melting the resin with the waste heat from the retort.

The form of the retort possesses the advantage of greater strength from the vertical sides, which, with the flat floor, gives additional fire surface, and as there is little coke or anthracite coal used as a distributing material, this flat floor is very advantageous; the heads of the retort being provided with ground disks inserted in the bolted heads, the disks are readily removed, and inspection made of the working condition of the retort, by withdrawing the clamp screw, thus avoiding the necessity of break. ing the clay lute and removing bolts in the heads, to ascertain the working condition of the apparatus.

The cleaning tap at the rear, affords by the introduction of an iron rod, facility of removing obstructions in the outlet pipe, which is a descending (instead of ascending) one, by forcing them down or up the outlet pipe; the outlet being placed below the floor, prevents all the fluctuations of the


resin backwards and forwards, as in the case of neck retorts; should any tar be formed, it descends the outlet pipe into the well of the condenser. In the feed pipe, instead of the ordinary syphon, which is troublesome to clear, and liable to clog from the deposite at the bend, ours is a vertical tube, through which the melted resin descends into the front of the retort (when the cup is filled) by the pipe rising in the said cup.

Fig. 1.

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Fig. 1 is an exterior elevation of the stove, &.c.

Fig. 2.


Fig. 2 is a vertical longitudinal section of the stove, retort, and cooler. The same letters refer to the same parts in each figure.

Fig. 1, a represents the side of the stove: B the ende: c gates in the ends: G is an additional section, placed under the resin holder, H, where the resin is melted: 1 is a stop cock: n, movable head screwed to the retort by bolts: r the cooler, supplied with water, covering the outlet pipe through which the gas passes down to the condenser.

Fig. 2, c represents gates in the ends: D, the grate bars: E, a plate near the top of the stove, to spread the heat to the ends of retort: F, a sliding damper, by which the heat may be thrown directly under the resin holder, or up the chimney: J, is a funnel and descending tube: K, an as

J cending tube rising from the front end of the retort, and extending an inch or two above the lower end of J: L, a retort of a D form, with the arch springing high from its sides, the bottom perfectly flat: P, P, clamps securing the ground heads of the retort: the rough lines under the retort represent the fuel: the lines in the retort represent the coke charging: the plug at the end of the outlet pipe can be removed, and an iron rod inserted, to remove any obstructions: the stop cock immediately over the outlet pipe is used to blow off gas when it is made too rapidly.

For the Journal of the Franklin Institute. Remarks on the Indicator Diagrams of the Steamer Magnolia.By S.

H. GILMAN, Esq. To the Committee of Publications:

GENTLEMEN:— The steam gauges used on the steamer Magnolia, (the subject of my communication of Feb. 24th, p. 258,) were of the mercury compressed air variety, made by Borden, of New Orleans, and graded to the pressure of an open column of mercury, by which they were readjusted before leaving port on that trip. One was attached to the steam 'drum, (26 inches in diaineter and 20 feet long,) laying transversely on the top of, and attached to all of the boilers; the other was attached to the steam pipe, three feet above the cylinder; there could not be any variation observed between the two. It is well known that on gauges of this description the index points for high pressures are exceedingly fine, and it is somewhat difficult to determine the exact pressure indicated. The indicator was verified by weights on its piston, and found to be correct, and was repeatedly examined to ascertain if the indicated vacuum was not due to some derangement; but the instrument was believed to be correct and in good order. After noting, with no little astonishment, the apparent identity of boiler and initial cylinder pressures on the first cards taken, they were observed with the utmost care, and if any difference existed between the two gauges, or the gauges and indicator, the instruments were not uniformly graded, which is quite possible. The great diameter of steam pipe and pressure of steam is, however, a great reason, and perhaps a sufficient one, why there should be no perceptible difference indicated by the gauges used; by a more sensitive gauge like the æneroid, a marked difference could probably be observed.

The anomaly of a vacuum in an exhaust steam pipe open to the atmosphere, has frequently been observed by the collapsing of such pipes when made of too thin copper, and especially when used for heating cane juice. A pipe, 5 inches in diameter and 240 feet long, open at the end to the atmosphere, and made of 20 pound copper, with the steam from a 15 inch cylinder, 5 feet stroke, exhausting through it, collapsed 60 feet of its length when cane juice of a temperature of 70° Fahr. was. poured on it. Upon attaching an air pump to the same pipe, it required an atmospheric pressure of 20 inches of mercury to collapse a portion of the remaining piece. A safety valve pipe, 3 inches in diameter and 12 feet long, made of 18 pound copper, was observed to collapse upon closing the valve suddenly while steain was blowing off. It was observed when using the indicator on the Magnolia, that a medium initial cylinder pres

a sure, with a full supply of cold water to the heaters, always produced a marked vacuum in the cylinders, while a maximum or minimum pressure of steam in the cylinders produced a less marked effect.

Respectfully, &c. Cincinnati, April 18th, 1853.

Process for taking Photographic Landscapes on Paper. By Jno. STEWART,

Esquire.* Allow me to request your insertion in the Athenæum of the annexed communication, on the subject of Photography, in the form of a letter to myself from my brother-in-law, Mr. John Stewart, resident at Pau,who has been singularly successful in his application of that art to the depiction of natural scenery,—and whose representations of the superb combinations of rock, mountain, forest, and water, which abound in the picturesque region of the Pyrenees, are among the most exquisite in their finish, and artistic in their general effect, of any specimens of that art which I have yet seen.

The extreme simplicity of the process employed by him for the preparation of the paper, its uniformity, and the certainty attained in the production of its results, seem to render it well worthy of being generally known to travelers. It need hardly be mentioned that the air-pump employed may be one of so simple a construction as to add very little to either the weight, bulk, or expense of the apparatus required for the practice of this art. The obtaining of a very perfect vacuum, for the imbibition of the paper, being a matter of little moment, a single barrel (worked by a cross handle by direct pull and push), furnished with a fexible connecting-pipe, and constructed so as to be capable of being clamped on the edge of a table, would satisfy every condition. I remain, &c.

J. F. W. HERSCHEL. 32, Harley Street, Dec. 7.

My Dear Herschel ---Thanks to the valuable indications of Prof. Reg. nault, of the Institut, I have been enabled to produce, what appear to me, most satisfactory results in Photographic Landscapes on Paper. In this remote corner (so deficient also in resources for experiment) I feel that I am but very partially acquainted with the results obtained and the progress making in the great centres, Paris and London; but I think that, in detailing the simple process and manipulation I now adopt, indications of some value, and suggestive of further improvement to fellow-laborers in the art, may be found; and if you are of the same opinion, you will per

* From the London Atheneum, December, 1852.

pure water.

haps facilitate the communications of these details to our photographers at home.

The following observations are confined to negative paper processes, divisible into two-the wet and the dry. The solutions I employ for both these processes are indentical and are as follows:

Solution of iodide of potassium, of the strength of 5 parts of iodide to 100 of

Solution of aceto-nitrate of silver, in the following proportions : 15 parts of nitrate of silver; 20 of glacial acetic acid; 150 of distilled water.

Solution of gallic acid, for developing a saturated solution.

Solution of hyposulphite of soda; of the strength of 1 part hypo. of soda to from 6 to 8 parts water.

The solutions employed are those reduced to their simplest possible expression, for it will be observed that in iodizing I employ neither ricewater, sugar of milk, fluorine, cyanure, nor free iodide, &c. &c.; but a simple solution of iodide of potassium (the strength of this solution is a question of considerable importance, not yet, I think, sufficiently investigated).

For both the wet and the dry processes I iodize my paper as follows: In a tray containing the above solution I plunge, one by one, as many sheets of paper (twenty, thirty, fifty, &c.,) as are likely to be required for some time. This is done in two or three minutes. I then roll up loosely the whole bundle of sheets, while in the bath; and picking up the roll by the ends, drop it into a cylindrical glass vessel with a foot to it, and pour the solution therein, enough to cover the roll completely (in case it should float up above the surface of the solution, a little piece of glass may be pushed down to rest across the roll of paper and prevent its rising). The vessel with the roll of paper is placed under the receiver of an air-pump and the air exhausted; this is accomplished in a very few minutes, and the paper may then be left five or six minutes in the vacuum. Should the glass be 100 high (the paper being in large sheets) to be inserted under a pneumatic pump receiver, a stiff lid lined with india rubber, with a valve in the centre communicating by a tube with a common direct. action air-pump, may be employed with equal success. After the paper is thus soaked in vacuo it is removed, and the roll dropped back into the tray with the solution, and then sheet by sheet picked off and hung up to dry, when, as with all other iodized paper, it will keep for an indefinite tiine.

I cannot say that I fully understand the rationale of the action of the air-pump, but several valuable advantages are obtained by its use:- 1st, The paper is thoroughly iodized, and with an equality throughout that no amount of soaking procures, for no two sheets of paper are alike, or even one, perfect throughout in texture; and air bulbs are impossible. 2d, The operation is accomplished in a quarter of an hour, which generally employs one, two, or more hours. 3d, To this do I chiefly attribute the fact that my paper is never solarized even in the brightest sun; and that it will bear whatever amount of exposure is necessary for the deepest and most impenetrable shadows in the view, without injury to the bright lights.

Wet Process.—To begin with the wet process. Having prepared the

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