1849.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



28 



leave a semicircular aperture between their conical and concave 

 circumferences corresponding to the groove. The effect of these 

 rollers is to bend the edges of the already bent plate in towards 

 each other, and down upon the mandril. The plate then slides, 

 with the mandril inside, under another revolving grooved roller, 

 which completes the bending down of the edges, and renders it 

 more effectual and permanent, and the tube is thereby completed. 

 The seam may be closed by the means usually employed. 



The tubes may be made oval or polygonal by forming the groove, 

 the concavities, and conve.xities of the rollers to suit the required 

 shape. 



BOOMERANG PROPELLER. 



Moses Poole, of the Patent Office, London, gentleman, for 

 '■'■ improremetits in propelling vessels." (Communicated from Lieut.- 

 Colonel Sir T. Levingston Mitchell.) — Granted May 2(i ; En- 

 rolled November 35, 1848. 



This propeller is called by its inventor the " Boomerang propel- 

 ler," from its action being supposed to be similar to that of the 

 boomerang, a wooden missile used by the natives of New Zealand. 

 On observing the motion of the boomerang in the air, whirling 

 round a hollow centre and leaving a vacant centre of gravity, it 

 occurred to Lieut-Col. Mitchell that its centre of motion would 

 be found to be on a right line, which wo\ild divide the boomerang 

 into tliree portions, in such manner as that the eccentric portions 

 should equal the central one ; and this he subsequently proved to 

 be the case. The bearing of the boomerang propeller, in which 

 the rotary shaft fits, is consequently to be placed in this newly- 

 discovered centre of motion, and suitably attached. The advan- 

 tages of this form of propeller are stated to consist in itS working 

 in the water obliquely to the radius of rotary motion, and being 

 free from lateral pressure. 



The form of this propeller and its centre of motion are shown 

 in the annexed diagram, A being the shaft on which it revolves, 

 and B the propeller blade. 



PREVENTION OF SMOKY CHIMNEYS. 



Sir Henry Hart, Commissioner of Greenwich Hospital, Rear- 

 Admiral R.N., for ^'■improvements in apparatus for preventing what 

 are called smoky chimneys." — Granted June 13 ; Enrolled December 

 13, 1848. 



The claim of the patentee of this invention is for the employ- 

 ment of wheels made to rotate by the wind, so as to withdraw tlie 

 air from the cliimney or flue, and brought into position by means 

 of an arrow or vane. The patentee represents three modes of 

 applying his invention. One consists in placing a fan-wheel par- 

 tially within the revolving part of the top of the chimney; so that 

 a current of air may act upon the fans which project above it, and 

 thereby create a draft. Another, in c\itting away a portion of the 

 top part of the chimney, and placing the fan-wheel therein, taking 

 care however to leave a portion of the fans exposed to the action 

 of the wind. A third, in placing the fan-wheel within the side of 

 the chimney fronting the wind, and covering the top fans with a 

 shield, so that tlie air may act upon the bottom ones, and drive the 

 smoke up the chimney. 



STEAM-BOILERS. 



William Seaton, of Camden-town, Middlesex, gentleman, for 

 " improvements in closing tubes, and in preventing and removing in- 

 crustation of boilers. — Granted May 30 ; Enrolled November 30, 

 1848. 



The first part of this invention consists in a method of closing 

 the ends of the tubes of steam-boilers, by contracting the metal 

 into a hemispherical form. When the tubes are of iron they are 

 heated to a welding heat, and placed on a vertical mandril, with 

 the end to be closed projecting slightly bej'ond it, and submitted 

 to the action of a suitably-formed die under pressure. When the 

 tubes are of copper, or of any alloy of that metal, they are sub- 

 mitted to the same process, with the exception of heating ; and as 

 the end cannot be perfectly closed, a small hole is left or made in 

 it, which is afterwards closed by a rivet of the same metal, in the 

 usual way. 



The second pai't of the invention consists in removing and pre- 

 venting incrustation in steam-boilers, by precipitating the lime 

 (of which the incrustations are generally formed), by oxalic acid, 

 or carbonate of potash, or carbonate of soda, or other chemical 

 agents, in a tank, and filtering it through charcoal and sand. Or, 

 in employing chemical agents, such as nitric, muriatic, or acetic 

 acid, «S;c., to hold the lime in solution, and enable it to be blown 

 off from time to time. Or, in using in the steam-boiler or gene- 

 rator, sawdust or charcoal, w hich by its mechanical action prevents 

 the formation of deposits. ^Vhen operating on salt water, salt, 

 soda, or saltwort is used. The relative quantities of the chemical 

 agents to be employed, are to be determined by a previous analysis 

 of the water ; and to remove any incrustation which may have 

 been previously formed, an excess of the chemical agent employed 

 must be used. 



GAS APPARATUS. 



Richard Barnes, of Wigan, Lancashire, gas-engineer, for "cer- 

 tain improved apparatus for manufacturing gas for illumination; part 

 of which improvements is applicable to retorts for distilling pyrnligneous 

 acid, and other similar purposes" — Granted June (J; Enrolled De- 

 cember 6, 1848. 



This apparatus is intended for the manufacture of gas in a small 

 way. The stove is built of fire-brick, with openings in the front 

 or side, but without grate or bars. The retort is suspended in the 

 stove by its flanges, which rest upon horizontal iron supports let 

 into the brickwork, and to which is attached a circular iron plate, 

 standing upwards. The cover is formed with two rims, one within 

 the other. The inside one takes into a groove formed by the pro- 

 jection of the retort above the flanges and the circular iron plate, 

 while the outside rim dips into another groove, filled with water, 

 and supported from the brickwork of the stove. The circular iron 

 plate passes up between these two rims, so as to intercept the ra- 

 diation of heat from the inside one, and consequently to prevent 

 the evaporation of the water which is contained in the groove in 

 which the outside rim dips. The tar, &c., which drips from the 

 cover between the projection of the retort and the inside rim, 

 together with the water-joint, prevent the escape of gas into the 

 atmosphere. 



Inside the retort is the cradle for holding the coal from which 

 the gas is to be evolved. The gas passes from the retort, through 

 a pipe fitted into the cover, into the refrigerator, the hydraulic 

 main, the condenser, the wash vessel, the puiifier, and lastly into 

 tlie gasometer. Tlie gasometer contains the purifier, the advan- 

 tage of which arrangement is, that the gas is constantly exposed 

 to the action of the lime. The gas, as it is evolved, passes through 

 the apparatus into the gasometer: and when the coal is exhausted, 

 the cradle is taken out, and placed in an extinguisher, so con- 

 structed as to prevent the admission of air to the coke, and also 

 the escape of noxious vapours from it. 



The patentee claims the constructing the stove with openings in 

 front or in the sides, but without grate or bars, and in closing the 

 mouth of the retorts used in the manufacture of coal gas, or py- 

 roligneous acid, or other similar purposes, by a cover made gas- 

 tight by a water-joint. Also, the peculiar construction and gene- 

 ral arrangement of refrigerator, condenser, wash vessel, purifier, 

 and gasometer, as described. 



