provements in the construction of the tubular flues of Steam Boilers. Enrolment Office, May 6, 1842.

The inventions which are the subject of this patent are less " improvements in the construction of the tubular flues of steam boilers," than improvements in the mode of manufacturing tubes in general; and it is in the latter sense, in fact, that the most important of them are claimed by the patentee. Nothing, however, is better settled than that a patent which is founded on a deceptive title, and linked to a specification which claims more than the title can possibly cover, is invalid (though possibly not past mending). What the inventions are, may be gathered from the claims of the patentee, which we subjoin.

"What I claim, as the first part of my invention, is the mode of welding iron or steel tubes, by drawing them through dies or between grooved rollers, when, and at the same time as, drawing such tubes or mandrils, the mandril being a necessary and important part of the mechanical apparatus in producing the welding.

"Secondly, I claim the welding of iron or steel tubes by hammering upon a mandril, at the same time I am drawing the tube from the fire along a mandril, so that the tube is welded on and drawn over a mandril at one process.

"Thirdly, I claim the application of either iron or steel tubes when coated with copper, brass or other alloys of copper, in the construction of tubular flues for steam boilers.

"And Fourthly, I claim in the construction of tubular flues of steam boilers, the application of welded iron or steel tubes, which have been drawn through a circular hole or die, or between rollers, and which have been drawn over a mandril, for the purpose of smoothing the external and internal surfaces of the tubes, and for regulating the thickness of the metal.".

NOTES AND NOTICES.

Imprinting without contact or agency of Light.Mr. Breguet the celebrated watchmaker, has addressed a letter to the French Academy, in which referring to the discovery of Dr. Moser of Konigsberg, (see Mech. Mag No. 992, and p. 156,) that the figures of objects can be transferred from one surface to another without contact, or the agency of light, he states, that he has frequently seen on the polished inner surface of the gold cases of watches, a distinct impression in reverse of the name of his house, which had been transferred from the engraved letters, on the covering of the works, which did not touch the case. Our friend Mr. Prosser of Birmingham, has also informed us (before the announcement of Mr. Breguet's communication,) that having thrown a newspaper loosely on the top of a

speculum, which was lying on a table with the concave side uppermost, he was sometime after surprised to observe, on removing the paper, and looking at the speculum, that there was a distinct impression upon it of several lines of the print, and that the impression was strongest in the centre, where it is certain no contact could have taken place. As there appears to be some difficulty in giving this new phenomenon a sufficiently distinctive name, we beg to suggest that it may very fitly be called after its first promulgator-Moserotype.

Recovery of H. M. S. Magnet.-Accounts from Sweden state that this vessel has been raised from the bottom of the Malmo roads, by means of a diving apparatus, invented by Count de Wenkerheing. Her masts, sails, and rigging are stated to be in good condition. In the hold were discovered three skeletons, and the body of a man in nearly a perfect state of preservation. The Magnet (built of oak,) mounting 18 guns, foundered in the above roads in the year 1809, thus making the time of her lying under water a period of 33 years.

The Papal Steamers.-The arrival in Rome of the three steamers constructed in England for the Pope, was the occasion of a popular feast, at which the principal functionaries of the State, the Cardinals, and a number of distinguished foreigners assisted. Notwithstanding the shallowness of the Tiber, the windings of the river, and the sand-banks which frequently obstruct its bed, the steamers ascended, in four hours, a distance which generally required nearly as many days.

Continental Barbarism.-The Moniteur des Chemins de Fer states that nearly one-half of the labourers employed on the Vesdre Railroad are females, who are preferred by the contractors to men for works of importance, from their superior docility, strength, and courage. "The country of Liege has," it is said, "this peculiarity, that the females undertake all those works which require superior skill and application that in other countries are reserved for men."

Mines and Minerals of the United States.-The production of iron, in 1840, amounted to 286,903 tons, in which 804 furnaces were employed; of bar iron the production was 197,233 tons, in which 795 forges, &c., were employed, the consumption of fuel for both these branches being 1,528,110 tons, while the amount of capital invested was 20,432,131 dollars, and the number of hands employed, including mining operators, 30,497. The production of lead amounted to 31,239,453 lbs., which employed 120 smelting-houses, 1,017 men, and an investment of 1,346,756 dollars. The production of gold was valued at 529,605 dollars, employing 157 smeltinghouses, 1,046 men, and an investment of 234,325 dollars; and the production of all other metals at 370,614 dollars, affording employment to 728 men, with an invested capital of 238,980 dollars. From the coal mines the products were 863,489 tons anthracite, and 27,603,191 tons bituminous; in the former of which there was invested 4,355,602 dollars, and in the latter 1,868,862 dollars. From the salt mines the produce was 6,179,174 bushels, in the raising of which 6,998,045 dollars was expended, and 2,365 men employed. And the value produced from the granite, marble, and other stone works was 3,695,884 dollars, employing 7,859 men, with an invested capital of 2,540,159 dollars.

INTENDING PATENTEES may be supplied gratis with Instructions, by application (postpaid) to Messrs. J. C. Robertson and Co., 166, Fleet-street, by whom is kept the only COMPLETE REGISTRY OF PATENTS EXTANT form 1617 to the present time).

The improvements which are the subject of the present notice are founded on the following general considerations. In the common barometer, the pressure of the column of mercury, added to the atmospheric pressure on the surface of the mercury in the cistern, being equal to the atmospheric pressure on the exterior bottom of the cistern, it follows, that if we place the cistern, with its contents, upon the top of a spring, or other exactly adjusted balance, the depression caused in the balance will be no more than what is due to the weight at the moment of the cistern and its contents, independently of the barometric column -the weight of that column being coun. terbalanced by the atmospheric pressure on the exterior bottom of the cistern. But, as the mercury in the cistern is the source whence the barometric column is derived, and as the quantity in the cistern is increased or diminished according to the height of that column, it follows also, that as the barometric column is caused to rise or fall by variations in the weight of the atmosphere, so the weight of the cistern will be proportionally increased or diminished, and the spring, or other balance on which it presses, be to the saine extent raised or lowered. It is further obvious, that if we ascertain how many inches, or parts of inches, are included within the extreme range of the barometric column, and what the weight of so many inches or parts of inches of mercury is, and to what extent the addition of such weight to the cistern will cause the spring or other balance to be depressed, we may from these data construct an index, which, being attached to the balance, will show on inspection the smallest changes in the height of the barometric column.

This, therefore, is what Mr. Readman, the present patentee, has done; and, by so doing, obviated three acknowledged defects in the barometers commonly constructed, namely, first, the difficulty of ascertaining the proper allowance to be made for the expansive effect of changes of temperature on the barometric column; secondly, the smallness of the range; and, thirdly, the disturbing influence of alterations in the level of the mercury in the cistern.

Fig. 1 of the prefixed engravings shows the manner of constructing a wheel barometer on this principle.

abc is a cylinder containing mercury; de, a second cylinder, which floats in the mercury within the other, forming the cistern of the barometer, (the mercury in the cylinder a b c serving the same purpose as the spring balance before spoken of;) a2, the barometrical tube; f, a brass rim, which runs round the top of the cistern d e, and to the bottom of which is soldered the projecting circular plate, g; hi are two uprights, which are screwed into the plate g, and are united at top by a cross-piece, k; l is a toothed rack, which rises from the centre of the cross-piece, k; m, a toothed wheel, into which the rack works, and to the axis of which wheel is attached the pointer of a properly graduated dial-plate; n o, anti-friction wheels, attached on each side to the projecting rim g, and which work in grooves in the frame-pieces, rs; p, a third anti-friction wheel, against which the rack works as it rises and falls. To keep the rack in a direct line with the centre of the cistern, the tube of the barometric column is bent aside a little at t, as shown in the engraving. The mode of action is as follows. As the quantity of mercury in the cistern de is increased or diminished the cistern rises or falls in the mercury contained in the outer cylinder a b c, and through the medium of the uprights hi, and rack and wheel 1 m, the exact amount of the rise or fall is communicated to, and indicated by, the pointer of the index. When it is desired to render this instrument portable, the plate g is brought close down upon the cylinder a b c, so as to serve as a lid to it. The instrument is then held in an inclined position, till the tube a2 is completely filled; the tube a2 is next unloosed from its fastenings, and pressed against the bottom of the cistern, which is protected by a piece of soft leather, after which the stopper u is slid down the tube a2, and closes the mouth of the cistern.

By applying a fixed scale to the side of the tube a2 of an instrument of the preceding description, very minute changes in atmospheric pressure might be rendered perceptible; for, besides the actual lengthening or shortening of the barometrical column by changes of pressure, such a scale would indicate the rise and fall of the cistern, the amount of which could be added to the range of the column. Thus, suppose the column to fall from 31 to 28 inches: if the cistern were

fixed, the scale would indicate a fall of only 3 inches; but if the cistern is made to float in mercury, in the manner before described, so that it rises and falls in proportion to any increase or diminution in the quantity of mercury in it; or if it is placed on a spring or other balance, which is affected in the same way, then the barometric column will have a farther fall, proportionate to the depression caused by the addition of the three inches of mercury to the cistern.

The patentee gives the following directions for graduating the instrument:

"Assuming the extreme range of the barometric column to be 3 inches, the weight of these 3 inches should be ascertained, and an equivalent amount of mercury taken from the cistern, marking exactly the position of the index pointer, both before and after the operation. A quantity equivalent to the excess of the column above 28 inches is then to be deducted, and the remainder returned. For instance, supposing the weight of the 3 inches of the barometric column is 3 oz., and that the cistern stands at 28 inches, you should then, (proceeding as above directed,) return only 2 oz. instead of 3 oz., theoz. being deducted to allow for the

inch which the barometric column exceeds 28 inches, and upon the flowing of which into the cistern the index pointer will be carried to its original position. The space included between the two points is to be divided in the usual manner.'

Mr. Readman describes, also, a very ingenious arrangement, by which a barometer on his improved plan may have a balance on the steelyard principle applied to it. A representation of this arrangement is given in fig. 2.

a b is a metal cylinder fixed to the bottom of the frame or case which holds the cistern ed, (the diameter of the cylinder being a little larger than that of the cistern,) and which partly incloses that cistern. Round the top of the cistern there is a metal rim, which projects a little beyond the sides of the cylinder a b, and is bevelled on part of its under surface, to keep the cistern exactly in the middle of the cylinder ab; ef is a lever or steelyard, with a sliding weight, g, resting on a fulcrum at h; the short arm of the lever has a termination of a crescent form, (as shown in the separate view given in fig. 3,) the two branches or horns of which have conical points, which enter into corresponding holes in the rim of the cistern. To ascertain the height of the column, the lever is brought to a horizontal position,

by causing the short arm to press upwards against the gauge-point 1, simultaneously with which the crescent end of the same arm, catching hold of the rim of the cistern, raises it also, and, by means of the conical points inserted in the holes of the rim, keeps the cistern always at the same distance from the fulcrum. The sliding weight g is then moved towards the fulcrum, and the height of the column thus ascertained. The adoption of this plan will not interfere with the ordinary scale, which may be still retained in combination with it. When the steelyard lever is not required to be in use, it may be placed out of the way, in the vertical recess i k, to which there is an opening in the side of the framework."

To register the indications of his improved barometer, Mr. Readman judiciously avails himself of the newly-discovered art of photography:

"I place at the back of the cistern, or spring balance, a circular plate of metal, covered in front with photogenic paper, of the same size as the dial-plate, and make the centres of the two plates to coincide exactly. Betwixt the circumference of the dial-plate and the graduated circle on the face of it there is a margin or border left, of about an inch and a half in breadth, and across this margin I make a narrow slit, directly over or under the centre of the plate. Behind the dial, and before this slit, I place a slip of metal, which is attached to the cistern balance, or spring balance, the bottom of which, when the mercurial column is at its highest point, is on a level with the upper end of the slit. Now, as the rising or falling of the cistern or spring balance increases or diminishes the length of the line of light admitted on to the photogenic paper, then, by causing the registering plate to revolve, (by a weight, or by any other convenient means,) a circular border is formed on the photogenic paper, the outer edge of which represents exactly the fluctuations in the atmospheric pressure. But, as the preceding method answers only for the daytime, I adopt the following plan when it is desired to continue the registration during both night and day. To the cistern or spring balance I affix a pencil, the point of which is made, by means of a spring, to press lightly on a surface of common paper stretched over the registering plate, so that on the plate being caused to revolve, (by a weight, or otherwise,) the pencil register, by corresponding lines on the paper, the rise and fall of the barometric column."