Billeder på siden
PDF
ePub

Yardley's, for manufacturing Glue.

239

is to be cut into square cakes, and dried upon nets, as in the ordinary process of glue making.

It is observed in the specification that "the boiler should be proved at one hundred and fifty pounds to the square inch, as it is worked at about one hundred. The extractor, also, made of cast or wrought metal, should be proved at fifty pounds to the square inch, as it is worked at fifteen. The forcing supply pump, and other details of the boiler, forming no part of my invention, I have omitted."

Inrolled, May, 1822.

[ocr errors]

At the premises, in Camberwell, where this apparatus was erected, an unfortunate accident occurred, on the 29th of September last; the boiler of the engine exploded; two persons were killed, several severely hurt, and the buildings shattered into a heap of ruins. This explosion appears to be attributable to two causes; first, the injudicious form of the boiler (which was waggon. shaped), and, secondly, the badness of its manufacture. Waggon-shaped boilers, which generally prevail, are extremely injudicious, because a volume of steam, expanding equally on all sides, always tends to press the vessel which contains it into the form of a globe, or of a cylinder with spherical ends. The bottom of a waggonformed boiler' usually protrudes inwards, forming an arch over the fire, against which convexity the steam in the inside exerts a force, tending to press the boiler into the reverse form; hence the angular parts at bottom experience the greatest strain.

The bottom of the boiler in question was attached to the sides by a single row of stout rivets, the perforations for which were so exceedingly close to each other, that

more than half the substance of the metal at the rivet holes was removed, and the upper and lower parts of the boiler, united only by the intervening pieces, of less than half an inch in breadth. The fracture took place at one end of the boiler, in the line of the rivets, and the force of the steam rent it in that weak part from end to end, leaving the bottom stationary, and carrying away the upper part of the boiler, in an oblique direction through the walls of the building, to a distance of forty or fifty feet.

The mode by which this boiler appears to have been proved is a very inaccurate one; cold water was forced into it so as to produce a pressure equal to about seventyfive pounds upon every square inch of its surface; and, when the force exceeded that sum, a valve was to rise and allow vent. This valve, however, was formed of the frustum of a cone inverted, and it was presumed that the smaller section of the frustum, against which the column of water acted, represented the surface (say equal to a square half inch), upon which the pressure was exerted; but by the water insinuating itself into the seat of the valve, under the whole surface of the cone, the pressure exerted was upon an area equal to the surface of the broadest part of the frustum, (say equal to a square inch,) so that the boiler was only proved at about one quarter the pressure calculated.

There is another circumstance, which, though of minor importance, seems to indicate that proving by cold water pressure is not perfectly conclusive; the particles of metal, under the temperature of cold water are held together by a certain attraction of cohesion; but when the metal becomes heated, these particles are farther removed from each other, the attraction is weakened, and, consequently, the vessel is not so strong.

THE DEN PUBLIC LIBRARY

ASTOR, LENOX AND TILDEN FOUNDATIONS

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][subsumed][merged small][merged small][merged small][subsumed][merged small][merged small][merged small][merged small][merged small][merged small][graphic][subsumed][subsumed][merged small]

Gardner's, for a Stay to correct Deformity of Shape. 241

To DENNY GARDNER, of Edmund Place, Aldersgate Street, London, for a Stay, particularly applicable to supporting the body under Spinal Weakness, and correcting Deformity of Shape.

THIS invention is a jointed, lateral steel stay, one of which is proposed to be placed under each arm of the patient, and may be attached to the shape or body, of ordinary stays for a female, as shewn by dots, Plate XIII. fig. 7; or to a riding, or body belt for a male patient. This improved stay is composed of steel, with joints, as shewn at fig. 8; and is intended to be secured to the ordinary body of a woman's stays, by means of flaps and lappets, tied or laced tightly to the shape. The ends of each steel support is to be formed as a crutch head, and covered with leather, or other soft material; the upper crutch to sit close under the arm; and the lower crutch to rest upon the hip, the requisite length being adjustable by means of screws, so as to suit the size and circumstances of the wearer.

Fig. 8, shews one of these improved supports, removed from the body of the stays. Circular holes, b, are made in the upper crutch piece, which are tapped and intended to receive screws; a, and b, are elongated holes in the upper adjusting plate, through which these screws are to pass; c, is another screw, which is to form the pivot, or joint, upon which the crutch shall be enabled to move a short distance, backward or forward; e, e, e, are several holes, into which screws, d and ƒ, are to be introduced, by which the length of the stay is to be regulated. d, or f, may either of them form a pivot, or joint, enabling the middle part of the stay to move; which may be found desirable, either in addition to, or as a substitute for, the I i

VOL. IV.

« ForrigeFortsæt »