a question; but the result of the before-named experiments tend to lead to the supposition, that such may be the case.

Bridgewater Foundry, Patricroft, near Manchester, May 10.

Lond. Min. Journ.

Paper-hangings prepared by means of Nitrate of Silver and other Salts.

M. Larocque presented a paper to the Academie des Sciences, Paris, explaining a new process for coloring and designing paper-hangings. He observes, that nearly all the salts are volatilized under the influence of vapor from water or saline solutions, and that the nitrate of silver, among other salts, on account of its easy reduction, would furnish a great variety of shades of color; and by means of reserves made in the paper, any designs in white might be obtained. The following is the process employed:-Take of pure nitric acid, sp. gr. 1.50, two parts; and distilled water, one part. Place the mixture in a porcelain capsule and heat it, throw in about two ounces of silver, and continue to apply heat until the action of the acid on the metal has ceased; with this quantity of silver 700 or 800 sheets of paper may be colored. In this operation but a very small loss of silver will be found, for the residue can be formed into nitrate of silver and sold; or, if calcined at a red heat in a crucible with carbonate of soda, the metallic silver may be obtained and employed for a new operation. In order to obtain good designs, it is necessary to operate in a place well lighted and out of currents of air. Civ. Eng. & Arch. Journ.

Improvement in the Safety Lamp.

At a recent meeting of the Geological and Polytechnic Society of the West Riding of Yorkshire, the Rev. W. Thorp produced a new lamp which will remedy all the defects in the lamp of Sir H. Davy; affording five times more light, and being, it is said, safe in every condition of the coal mine. In order to obtain more light, the Rev. W. Thorp introduces the solar burner, characterized by the circular wick, and the air admitted through its centre from the bottom of the lamp, protected of course by gauzes of wire. Connected with this part is an adjustment, placed outside of the cistern, by which the wick can be raised or lowered. Over the light is applied a chimney of iron, based with a few inches of glass, with air admitted to supply the exterior of the flaine from the inside of the lamp. This is so fixed that it cannot be broken from the ordinary falls to which these lamps are liable to be exposed. Having obtained a much higher illuminating power than that generally used by miners, the next object being to ensure perfect safety in every condition of the mine, there are inserted into the chimney four or five chambers of wire gauze, so that the flame of ignited gas has to traverse eight or ten meshes before it can possibly reach the exterior fire-damp; but as one mesh, as in the old lamp, is safe unless exposed to a current, and as no lateral current of gas or air can be exerted upon the flame on account of the chimney

the lamp is perfectly safe. And it is found, by any artificial means, utterly impossible to pass flame through these chambers of gauze, so that it appears to be quite safe under every circumstance and condition of the mine. There are other advantages over the Davy lamp of no inconsiderable value:-1. It requires trimming only once a week; 2. The oil does not fall out if laid on one side; 3. It is much more easily cleaned; 4. The cheapest oil can be used in it. As no patent will be taken out for the new lamp, and the whole of the improvement is generously given to those interested in collieries, the Rev. W. Thorp expresses an earnest wish that all lamps may be purchased of Mr. W. Ramsden, of Wakefield, through whose assistance he has been enabled to produce the lamp.

London Athenæum.

Copper-wire Cord for Window-Sash-Lines, &c.

Messrs. Newall & Co. have greatly improved their patent copper wire cord, which is now made extremely flexible, and is well adapted for window-sash-line, hot-houses, lightning conductors, picture-cord, clock-cord, bell-hanging, and many other purposes for which hempen rope has hitherto been used; the advantages being that it is cheaper, much more durable, and one-sixth part the bulk of hempen rope. Civ. Eng. & Arch. Journ.

BIBLIOGRAPHICAL NOTICES.

Statistics of Coal, &c., &c. Prepared by RICHARD COWLING TAYLOR, Philadelphia: J. W. Moore, 1848.

Mr. Taylor, the author of this book, has long been known as a most assiduous and pains-taking geologist, to whose laborious and minutely accurate investigations we owe much of our knowledge, especially of our Pennsylvania coal fields. His unpretending modesty, and readiness to yield to others, has prevented his name from being as well known to the public as those of others, but we doubt, whether, in the whole list of those who have devoted themselves to American Geology, there is one of more solid acquirement, and more profound judgment a more accurate observer, or more indefatigable laborer, than Mr. Taylor. As President of the Dauphin Coal Company, it was his duty to watch the progress of mining industry, and we knew that he was in possession of a great mass of statistical facts upon this subject.When, therefore, it was first announced that he was about to publish a work upon this subject, our expectations were highly excited, and we should have been deeply disappointed, if we had found the proposed volume of only moderate value; yet we confess that we were in no wise prepared for such an extensive and elaborate digest of important information, as that which he has presented. We would scarcely have thought it possible, that one individual, especially in this country, where the facilities for such a purpose are so few, and with

other and laborious duties daily pressing upon him, should have collected together such a mass of facts, and made of them so well arranged, and so delightful a book. And now that, for about the twentieth time, we take it up to look over its contents, and read an occasional chapter, our astonishinent is in no degree abated at the extent and variety of the information which it affords; for this work is by no means confined to the development of mere tabular statements of the production of this important fuel, in various countries, but embraces within it every kind of information which those interested in this subject would be likely to seek. The geology of coal fields-the various fossils which characterize them-the mode of sinking, and of working the mines the precautions taken to secure the health and lives of the miners; in short, every matter which is of importance to those engaged in mining projects, or interesting to the general reader, are here considered. Nor is it confined to the study of coal only, but embraces all those fossil productions which bear an analogy to it-brown coal, peat, bitumen-and even the statistics of wood, as a fuel, have a place in its pages; and the reader will find, moreover, much valuable information on the subject of the manufacture of iron, a subject which the author justly observes, is "so interwoven with nfatters essential to our main subject, that a considerable mass of information has been necessarily incorporated in our pages."

The method in which these various subjects are treated, is worthy of their extent and importance. The style is perfectly plain and unpretending. Great care has evidently been taken to acknowledge the labors of those from whom the information was obtained. The work is properly and judiciously illustrated by maps and diagrams, and we especially recommend to the notice of our readers, the ingenious and striking method of presenting comparative results, by proportional

square areas.

We hope,

We cannot do more than notice this book at present. when we have had time to give it the study which it deserves, to recall the attention of the public to it, in a more extended review, and we shall, by the permission of the author and publisher, treat our readers, from time to time, with some of its valuable information.

We take our leave of it, for the present, with the sincere hope, that its publication may prove as profitable to the author, as it undoubtedly will be to the public.

F.

We have received a note from Prof. W. R. Johnson, the American editor of Knapp's Chemical Technology, requesting us to republish the article upon the cost of manufacturing illuminating gas, in our Journal, in order that our readers may certainly know how far our criticisms upon Prof. J. are well founded. We have given already the reasons why we do not believe our Journal to be the proper vehicle, either for personal accusations against the persons in charge of the Philadelphia Gas Works, or for their defence against such accusa

tions; we must, therefore decline acceding to Prof. Johnson's request. We have already said that, as the citizens of Philadelphia are those who are most interested in the truth or falsehood of these charges, the most of which have no scientific bearing whatever, it is in the daily press of our city that the discussion ought to be carried on, and if the charges find their way into the newspapers, the friends of the parties concerned will, we have no doubt, reply, and the truth will be developed. But the questions, whether the Superintendent of the Philadelphia Gas Works has, or has not, "a direct or indirect interest in keeping up the price of gas;" or if he has such, whether it influences him against the adoption of proper improvements; and whether he does, or does not, "surround the subject of gas making with mystery," and other questions of this nature, we again most respectfully suggest to Prof. Johnson, have no appropriate place in our Journal, nor do we think they have in his edition of Knapp's Chemical Technology. COM. PUB.

FRANKLIN INSTITUTE.

COMMITTEE ON SCIENCE AND THE ARTS.

Report on A. G. HECKROTTE's Self-Acting Safety Coupling for Rail road Cars.

The Committee on Science and the Arts, constituted by the Franklin Institute of the State of Pennsylvania for the promotion of the Mechanic Arts, to whom was referred for examination the self-acting safety coupling for railroad cars, invented by A. G. HECKROTTE, Washington city, D. C.,

REPORT

The apparatus consists of a flat box, figs. 1 and 2, containing the necessary arrangements for securing the head of the coupling bar A, which is received in an opening by guides which are constructed with a sufficient flare to allow of its entrance at any angle at which it would be likely to be presented. The bar on its entrance, finds itself opposed by a disk or friction roller, C, on one side and a tumbler, B, of peculiar shape on the other; a slight revolution of each of these allows the head of the bar to pass, until, in revolving, a notch on the tumbler is caught by a trigger, D, arranged for the purpose, and which prevents the bar, when acted upon by traction, from being drawn from the box. The trigger is allowed to extend beyond the box and front of the car, so that, when the train is brought into such a position as to endanger the passage of a car by being thrown too obliquely one to another, the trigger is acted upon by the front of the car preceding and the coupling is immediately disengaged.

The arrangement of the apparatus is such that the cars are coupled instantly by merely running them together, and the fastening is completed without any farther intervention; in this the chief merit of the invention consists; it also has the important advantage of permitting

the cars to be uncoupled at will, even when all the couplings are tightly strained, which cannot be done by the usual arrangement.

The committee are convinced of the great utility of Mr. Heckrotte's invention in the coupling and uncoupling of cars in a neat and effective manner, with much less danger to life and limb than the ordinary method.

The statistics in possession of the committee are not sufficient to assure them that the immediate uncoupling of cars in motion is more likely to prevent accidents than the retaining them together; there are facts enough, however, in which the lives of passengers have been saved by the continuity of the train being preserved, to warrant a doubt as to this question.

Mr. Heckrotte has a very ingenious and neat method of constructing the tumbler, the shape of which requires great nicety in its formation; a plan of this is shown in the drawing accompanying the report.

By order of the Committee,

June 8th, 1848.

Report on MR. S. COLTON's Improved Door and Pad-locks. The Committee on Science and the Arts, constituted by the Franklin Institute of the State of Pennsylvania for the promotion of the Mechanic Arts, to whom was referred for examination an improvement in Door and Pad-locks, invented by Sabin Colton, of the City of Philadelphia, Pennsylvania,

REPORT

That the peculiarity of Mr. Colton's locks is this:Three circular metal disks are placed in a frame having three grooves cut in it of the proper size, in which the disks turn freely and independently on the same axis. This frame carries the detent or catch