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Apparatus for determining the velocity of currents
396
~lechanics, Physics, and Chemistry.
publish a description of the apparatus, but, having inspected it minutely, and seen it in operation, we are enabled to state that great ingenuity and mechanical skill have been bestowed upon its contrivance. Of course the discovery has rendered a counter improvement in the safe itself absolutely essential to security ; and it is with much pleasure that we are m a position to announce the introduction of such an improvemeat. By the eourlesy of the Metropolitan Police authorities, Mr. Chubb, the eminent lock and safe manufacturer, of St. Paul's Churchyard, has been allowed to examine and experiment with the instrument, and he has succeeded completely in providing a simple method of baffling its operation. The improvement consists in placing throughout that portion of the door which is in fror~t of the lock a number of hardened screwed steel plugs, sufficiently close to each to prevent either an ordinary drill or circular hollow cutter from passing through without encountering several of the plugs. These plugs of hardened steel have the effect of utterly destroying the edge of every description of cutter which can be used with the burglar's apparatus, and consequently render the safes secure from its operation. All Chubb's fire-proof safes and strongroom doors are now made with the above improvement, and old safes may readily have it applied. It has been protected by Letters Patent.
./tpparatusfor Determining the Velocity of Currents. M. Darey has proposed an improvement upon Pitot's tube apparatus for determining the velocity of currents. In Pitot's apparatus two parallel tubes, connected together at top and open below, the plane of the opening of one being parallel, and that of the other perpendicular to the current, were lowered into the stream, and the velocity of the current was determined by the difference of heights of the liquid in the tubes. The disadvantages were, that the instrument itself produced an eddy which modified the velocity to be determined ; that the extremities of the tubes were not sufficiently close, to be under the same circumstances ; and when a deep seated current was to be examined, the tubes required were of inconvenient length. In M. Darey's modification, the tubes have stop-cocks attached to them near their lower extremities, which are opened and shut by the same key, worked by cords from above : below the stop-cock, the tubes are both bent at right angles, and prolonged sufficiently to clear the eddy made by the solid part of the apparatus, and then terminated by openings, one parallel to, the other perpendicular to the current. The tubes are fixed upon a board attached to a vertical rod, upon which it works as a vane, so that the current itself keeps the openings of the tubes in the proper positions. The apparatus being lowered to the proper depth, the stop-cocks are opened, and when the levels of the liquid have been attained in the tubes, the eock is again elosed, and the tube raised and examined. Another stop-cock at the top of the apparatus allows the air to be compressed in the tubes, when it has to be entirely submerged, and thus avoid the inconvenience of using very long tubes.--Cosmos.
~lechanics, Physics, and Chemistry.
publish a description of the apparatus, but, having inspected it minutely, and seen it in operation, we are enabled to state that great ingenuity and mechanical skill have been bestowed upon its contrivance. Of course the discovery has rendered a counter improvement in the safe itself absolutely essential to security ; and it is with much pleasure that we are m a position to announce the introduction of such an improvemeat. By the eourlesy of the Metropolitan Police authorities, Mr. Chubb, the eminent lock and safe manufacturer, of St. Paul's Churchyard, has been allowed to examine and experiment with the instrument, and he has succeeded completely in providing a simple method of baffling its operation. The improvement consists in placing throughout that portion of the door which is in fror~t of the lock a number of hardened screwed steel plugs, sufficiently close to each to prevent either an ordinary drill or circular hollow cutter from passing through without encountering several of the plugs. These plugs of hardened steel have the effect of utterly destroying the edge of every description of cutter which can be used with the burglar's apparatus, and consequently render the safes secure from its operation. All Chubb's fire-proof safes and strongroom doors are now made with the above improvement, and old safes may readily have it applied. It has been protected by Letters Patent.
./tpparatusfor Determining the Velocity of Currents. M. Darey has proposed an improvement upon Pitot's tube apparatus for determining the velocity of currents. In Pitot's apparatus two parallel tubes, connected together at top and open below, the plane of the opening of one being parallel, and that of the other perpendicular to the current, were lowered into the stream, and the velocity of the current was determined by the difference of heights of the liquid in the tubes. The disadvantages were, that the instrument itself produced an eddy which modified the velocity to be determined ; that the extremities of the tubes were not sufficiently close, to be under the same circumstances ; and when a deep seated current was to be examined, the tubes required were of inconvenient length. In M. Darey's modification, the tubes have stop-cocks attached to them near their lower extremities, which are opened and shut by the same key, worked by cords from above : below the stop-cock, the tubes are both bent at right angles, and prolonged sufficiently to clear the eddy made by the solid part of the apparatus, and then terminated by openings, one parallel to, the other perpendicular to the current. The tubes are fixed upon a board attached to a vertical rod, upon which it works as a vane, so that the current itself keeps the openings of the tubes in the proper positions. The apparatus being lowered to the proper depth, the stop-cocks are opened, and when the levels of the liquid have been attained in the tubes, the eock is again elosed, and the tube raised and examined. Another stop-cock at the top of the apparatus allows the air to be compressed in the tubes, when it has to be entirely submerged, and thus avoid the inconvenience of using very long tubes.--Cosmos.