US867123A - Signal apparatus. - Google Patents

Signal apparatus. Download PDF

Info

Publication number
US867123A
US867123A US30646906A US1906306469A US867123A US 867123 A US867123 A US 867123A US 30646906 A US30646906 A US 30646906A US 1906306469 A US1906306469 A US 1906306469A US 867123 A US867123 A US 867123A
Authority
US
United States
Prior art keywords
signal
dial
visual
pipe
casing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US30646906A
Inventor
Frank Gowin
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to US30646906A priority Critical patent/US867123A/en
Application granted granted Critical
Publication of US867123A publication Critical patent/US867123A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B7/00Systems in which the movement produced is definitely related to the output of a volumetric pump; Telemotors
    • F15B7/06Details
    • F15B7/10Compensation of the liquid content in a system

Definitions

  • This invention relates to a signal apparatus of the pneumatic annunciator type, and particularly adapted for use in mines to indicate to an engineer both audible and visual signals to direct the starting of an engine to control the movement of a cage or lifting means in a mine shaft.
  • the present invention particularly embodies means for actuating the annunciator both from the top and a lower portion of a mine shaft to avoid confusion and accidents that might result if there was no definite or prearranged location of the signal operating means, and if there was no means by which the engineer could determine from what point the signal was given.
  • Figure 1 is an elevation of an apparatus embodying the features of the invention.
  • Fig. 2 is a detail elevation on an enlarged scale of a portion of the apparatus showing a part of the inclosing means therefor removed and a portion in section.
  • the numeral 1 designates an air pipe which extends from the top to the bottom of a mine shaft, and has a lower angular branch 2 and an upper similar branch 3. From the branches 2 and 3, compression cylinders 4 and 5 depend, one cylinder connected to each branch and having therein a piston 6 with a depending stem 7, terminating in a hand grip or projection 8 of any suitable form for operating the piston. The pistons 6 in the cylinders 4 and 5 will be provided with suitable packing to form a tight fitting in the cylinders.
  • a transmitting pipe 9 is connected to the pipe 1 and 111115 to the engine room forming part of the plant of the mine. The transmitting pipe is closed at its free extremity 10, and in like manner the 'branches 2 and 3 have their free extremities 11 similarly closed.
  • the pipe 10 cooperates with an annunciator apparatus, comprising a dial 12, having indicating means thereon, in the present instance being designated zero, or no signal point, and from then up to the numeral 8, in conformity with signal laws made and provided for the operation of a 'mine to protect life and property, and which, of course, varies in different localities, or according to specific State laws.
  • an annunciator apparatus comprising a dial 12, having indicating means thereon, in the present instance being designated zero, or no signal point, and from then up to the numeral 8, in conformity with signal laws made and provided for the operation of a 'mine to protect life and property, and which, of course, varies in different localities, or according to specific State laws.
  • an index hand or indicator 13 Movable over the face of the dial 12 is an index hand or indicator 13, which is operated by mechanism which will be now set forth.
  • the dial 12 is supported on a suitable casing 14, and the index hand or movable indicator 13 is attached to a shaft 15 centrally disposed in the casing 14 and dial 12, and having also secured thereon Within the said casing a ratchet wheel 16, the shaft 14 having one terminal of a return spring 17 attached thereto and the opposite terminal thereof secured to an adjacent part of the casing for automatically restoring the ratchet wheel 16 and the index hand or movable indicator 13 to normal position under certain releasing operations.
  • a reciprocating frame 18 is movably mounted in the casing 14, and is held by suitable guides 19.
  • This frame carries at one side a pull detent or dog 20, which is normally projected inwardly towards the wheel 16 and in engagement with one of the teeth of the latter, a spring 21 being used to hold the detent or dog 20 in its normal position.
  • a piston 22 Depending from the center of the bottom of the frame 18 is a piston 22, having a cavitied head 23, which is movable in a depending tubular extension 24, connected to the casing and having communication at its lower end with the pipe 9, as clearly indicated by Fig. 1.
  • the head 23 on the piston 22 snugly fits within the tubular extension 24, and is directly influenced by the pneumatic impulse transmitted thereto through the pipe 9 from pipe 1, when either of the pistons 6 is oper-- ated.
  • a stem 25 movable through the opening 26 in the top central portion of the casing 14, and having on its upper end a striker 27, which is adapted to contact with a gong or bell 28 supported above the indicator below 7 and providing a pneumatically controlled annunciator apparatus which will give both an audible and a visual signal or indication.
  • a stop dog or pawl 29 Cooperating with the main portion of the ratchet wheel 16 is a stop dog or pawl 29, fulcrumed at an intermediate point to a portion of the casing, and having its inner end toothed to take into the teeth of the ratchet wheel and prevent the latter from returning to normal position through the operation of the spring 17, until the said stop dog or pawl is-released.
  • the outer end of the stop dog or pawl is connected to a plunger 30, Working in a small cylinder or pipe 31 projecting upwardly through the casing 14 and having communieating therewith an angular branch 32 of a pipe 33 opening at its lower end into a dash pot 34 provided with a plunger 35.
  • a stem or rod 36 having a connection 37 which runs over to the lever of the controlling valve of the engine or within easy reaching distance of the engineer.
  • This dash pot apparatus just explained operates to release the stop dog or pawl 29 precisely at the time that the engine is started to either lower 01' hoist the cage in the mine shaft in accordance with the signal given to the en gineer through the medium of the pneumatic annunciator apparatus.
  • the inner toothed extremity of the stop dog or pawl 29 is normally held up in the path of rotation of the teeth of the ratchet wheel 16 by a spring 38 attached thereto and also connected to a part of the casing.
  • the proportions of the several parts of the apparatus explained may be varied, sincefrom practical experionce it has been found that the casing 14 should be about six inches in diameter and the dial about the same diameter, the casing being preferably three inches deep.
  • the ratchet wheel 16 should be about three inches in diameter, and provided with ten teeth.
  • the pipe 31 in which the piston or plug 30 is fitted is formed preferably of one-quarter inch gas pipe.
  • the preferred proportions with respect to the pipes l and 9 and the cylinders 4 and 5 are that said pipes be about two inches in diameter and the cylinders eight inches in diameter by eight inches in length. These proportions give the best effect in the operation of the signal apparatus.
  • the numerals used on the dial 12 are arranged in accordance with well known laws governing minesig nals, the numeral 1 being a signal to hoist the cage, 2 to lower the cage, and 3 men are coming up, and so on up to eight bells with the numeral 8.
  • the number on the dial at which the index hand or movable indicator stops will be controlled solely by the number of operations of the pistons 6 in the cylinders 4 and 5, and in accordance with the well recognized and legal code of signals, the operator at the bottom of the mine will give one push to the pistons 6 in the cylinder 4 and thereby cause the index hand 13 to move over the dial and stop at the numeral 1, which will notify the engineer controlling the hoisting and lowering of the cage that the cage is being elevated.
  • the operator at the top of the shaft will operate the piston6 in the cylinder 5 to give two distinct impulses, or push the piston twice and thereby throw the index hand 13 to the numeral 2, the index hand moving against the resistance of the spring 17, and the ratchet wheel 16 being checked against unreliable return movement by the stop dog or pawl 29.
  • the three bell signal will also be affected by operating the piston in the proper cylinder or prime actuating medium by giving three pushes thereto which will send as many impulses through the pipes l and 9 to'the casing 14. This same operation will be continued to give the number of signals de sired, and up to and including eight bells, or as many other bells as the indicator may permit, and in accordance with the prearranged signals by which the opera tion of the cage at the mine is controlled.
  • dial signal means Another advantage of this dial signal means is that should the engineer fail to hear the gong he can readily see by inspecting the dial 12 whether a signal has been given, and if he finds that the index hand 13 shows that a signal has been given he may at once respond thereto by operating his engine.
  • a signal apparatus of the class set forth involving visual and audible means, means for creating and transmitting a pneumatic impulse to the said visual and audible signal means for sinmltaneously operating the latter, means for automatically locking and temporarily holding the signal means in fixed position after movement, and means for simultaneously releasing both the visual and audible signal means :1.
  • a pneumatic nal apparatus in combination with a. controlling motor or engine involvinga visual and audible signal means, the visual signal means being provided with a movable indicator to temporarily tixcdly register the signal given, pneumatic impulse creating and conveying means. and means for automatically restoring the parts of the visual indicating means to normal position simultaneously with the actuation of the controlling motor or engine.
  • I11 a signal apparatus of the class set forth, the coinbination of a visual indicating means having a dial with signal indicating characters thereon, and an index movable thereover, means for temporarily holding the index in fixed position on the dial, means for creating and transmitting a pneumatic impulse to the dial, and automatically controlled means for automatically releasing and restoring the index to normal position.
  • a signal apparatus of the class set forth having means for creating and transmitting a pneumatic impulse, the means for creating the impulse being disposed at different elevations, simultaneously operating visual and audible signal mechanism interposed intermediately with respect to the said means and actuated by either of the latter, an automatic controlling means for restoring the signal mechanism to normal position 5.
  • a pneumatic signal apparatus having a simultaneously operating visual and audible signal mechanism involving respectively a dial bearing indicating characters thereon, an index hand movable over the dial, a ratchet wheel connected to the dial, a movable frame for operating the ratchet wheel having a depending piston element and an upwardly projecting striker, a pipe into which the said piston element projects, a gong arranged above the dial for engagement by the striker, devices for creating and transmitting a pneumatic impulse to the pipe having the piston element therein, and mechanism for automatically restoring the parts of the visual indicating means to normal position simultaneously with the actuation of a controlling motor or engine.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Testing Of Engines (AREA)

Description

No. 867,123. 4 PATENTED SEPT. 24, 1907.
P. GOWIN'. A SIGNAL APPARATUS.
APPLICATION FILED MAR.16,1906.
I fizveizfor 15%;? oal/L544 UNITED sTArps PATENT OFFICE.
' SIGNAL APPARATUS.
Specification of Letters Patent.
Patented Sept. 24, 1907.
Application filed March 16, 1906. Serial No. 306,469.
To all whom it may concern:
Be it known that I, FRANK GOWIN, a citizen of the United States, residing at Carlinville, in the county of Macoupin and State of Illinois, have invented new and useful Improvements in Signal Apparatus, of which the following is a specification.
This invention relates to a signal apparatus of the pneumatic annunciator type, and particularly adapted for use in mines to indicate to an engineer both audible and visual signals to direct the starting of an engine to control the movement of a cage or lifting means in a mine shaft.
The present invention particularly embodies means for actuating the annunciator both from the top and a lower portion of a mine shaft to avoid confusion and accidents that might result if there was no definite or prearranged location of the signal operating means, and if there was no means by which the engineer could determine from what point the signal was given.
It is well known that an engineer controlling the lifting apparatus at a mine must be guided to avoid mistakes and accidents by two different signals, one signal being given from the bottom of the shaft to indicate to the engineer that a hoist of the lifting means is desired, and a second signal from the top of the shaft to notify the engineer that a reverse or lowering move ment of the lifting means is desired. In the signal apparatus which has been commonly employed, it has often been perplexing to an engineer to determine whether he receives a signal from the bottom or the top of a shaft, and it the signal comes from the top of the shaft instead of the bottom, and the cage or skip is started off from the bottom when the men are just pushing a box of coal thereon, trouble and breakage will necessarily result. By the pneumatic annunciator or signal embodying the features of the present invention these disadvantages are avoided, as both a visual and an audible signal are conveniently presented to the engineer; and the visual signal will remain in its operated position, or to indicate an actuation by means of suitable numerals or other characters until the engine is started, when the index of the indicator will immediately return to zero position and be ready for a succeeding signal.
In the drawing, Figure 1 is an elevation of an apparatus embodying the features of the invention. Fig. 2 is a detail elevation on an enlarged scale of a portion of the apparatus showing a part of the inclosing means therefor removed and a portion in section.
Similar numerals of reference are employed to indicate corresponding parts in the views.
The numeral 1 designates an air pipe which extends from the top to the bottom of a mine shaft, and has a lower angular branch 2 and an upper similar branch 3. From the branches 2 and 3, compression cylinders 4 and 5 depend, one cylinder connected to each branch and having therein a piston 6 with a depending stem 7, terminating in a hand grip or projection 8 of any suitable form for operating the piston. The pistons 6 in the cylinders 4 and 5 will be provided with suitable packing to form a tight fitting in the cylinders. At an intermediate point a transmitting pipe 9 is connected to the pipe 1 and 111115 to the engine room forming part of the plant of the mine. The transmitting pipe is closed at its free extremity 10, and in like manner the 'branches 2 and 3 have their free extremities 11 similarly closed. The pipe 10 cooperates with an annunciator apparatus, comprising a dial 12, having indicating means thereon, in the present instance being designated zero, or no signal point, and from then up to the numeral 8, in conformity with signal laws made and provided for the operation of a 'mine to protect life and property, and which, of course, varies in different localities, or according to specific State laws.
Movable over the face of the dial 12 is an index hand or indicator 13, which is operated by mechanism which will be now set forth. The dial 12 is supported on a suitable casing 14, and the index hand or movable indicator 13 is attached to a shaft 15 centrally disposed in the casing 14 and dial 12, and having also secured thereon Within the said casing a ratchet wheel 16, the shaft 14 having one terminal of a return spring 17 attached thereto and the opposite terminal thereof secured to an adjacent part of the casing for automatically restoring the ratchet wheel 16 and the index hand or movable indicator 13 to normal position under certain releasing operations.
A reciprocating frame 18 is movably mounted in the casing 14, and is held by suitable guides 19. This frame carries at one side a pull detent or dog 20, which is normally projected inwardly towards the wheel 16 and in engagement with one of the teeth of the latter, a spring 21 being used to hold the detent or dog 20 in its normal position.
Depending from the center of the bottom of the frame 18 is a piston 22, having a cavitied head 23, which is movable in a depending tubular extension 24, connected to the casing and having communication at its lower end with the pipe 9, as clearly indicated by Fig. 1. The head 23 on the piston 22 snugly fits within the tubular extension 24, and is directly influenced by the pneumatic impulse transmitted thereto through the pipe 9 from pipe 1, when either of the pistons 6 is oper-- ated.
Rising from the center of the top of the frame 18 is a stem 25, movable through the opening 26 in the top central portion of the casing 14, and having on its upper end a striker 27, which is adapted to contact with a gong or bell 28 supported above the indicator below 7 and providing a pneumatically controlled annunciator apparatus which will give both an audible and a visual signal or indication.
Cooperating with the main portion of the ratchet wheel 16 is a stop dog or pawl 29, fulcrumed at an intermediate point to a portion of the casing, and having its inner end toothed to take into the teeth of the ratchet wheel and prevent the latter from returning to normal position through the operation of the spring 17, until the said stop dog or pawl is-released. The outer end of the stop dog or pawl is connected to a plunger 30, Working in a small cylinder or pipe 31 projecting upwardly through the casing 14 and having communieating therewith an angular branch 32 of a pipe 33 opening at its lower end into a dash pot 34 provided with a plunger 35.
Depending from the plunger 35 is a stem or rod 36 having a connection 37 which runs over to the lever of the controlling valve of the engine or within easy reaching distance of the engineer. This dash pot apparatus just explained operates to release the stop dog or pawl 29 precisely at the time that the engine is started to either lower 01' hoist the cage in the mine shaft in accordance with the signal given to the en gineer through the medium of the pneumatic annunciator apparatus. The inner toothed extremity of the stop dog or pawl 29 is normally held up in the path of rotation of the teeth of the ratchet wheel 16 by a spring 38 attached thereto and also connected to a part of the casing.
The proportions of the several parts of the apparatus explained may be varied, sincefrom practical experionce it has been found that the casing 14 should be about six inches in diameter and the dial about the same diameter, the casing being preferably three inches deep. The ratchet wheel 16 should be about three inches in diameter, and provided with ten teeth. The pipe 31 in which the piston or plug 30 is fitted is formed preferably of one-quarter inch gas pipe. The preferred proportions with respect to the pipes l and 9 and the cylinders 4 and 5 are that said pipes be about two inches in diameter and the cylinders eight inches in diameter by eight inches in length. These proportions give the best effect in the operation of the signal apparatus.
The numerals used on the dial 12 are arranged in accordance with well known laws governing minesig nals, the numeral 1 being a signal to hoist the cage, 2 to lower the cage, and 3 men are coming up, and so on up to eight bells with the numeral 8. The number on the dial at which the index hand or movable indicator stops will be controlled solely by the number of operations of the pistons 6 in the cylinders 4 and 5, and in accordance with the well recognized and legal code of signals, the operator at the bottom of the mine will give one push to the pistons 6 in the cylinder 4 and thereby cause the index hand 13 to move over the dial and stop at the numeral 1, which will notify the engineer controlling the hoisting and lowering of the cage that the cage is being elevated. The operator at the top of the shaft will operate the piston6 in the cylinder 5 to give two distinct impulses, or push the piston twice and thereby throw the index hand 13 to the numeral 2, the index hand moving against the resistance of the spring 17, and the ratchet wheel 16 being checked against unreliable return movement by the stop dog or pawl 29. The three bell signal will also be affected by operating the piston in the proper cylinder or prime actuating medium by giving three pushes thereto which will send as many impulses through the pipes l and 9 to'the casing 14. This same operation will be continued to give the number of signals de sired, and up to and including eight bells, or as many other bells as the indicator may permit, and in accordance with the prearranged signals by which the opera tion of the cage at the mine is controlled. The impulses coming through the pipe 9 ilom the pipe I to the casing 14 will directly affect the cavitied head 23 and cause the latter to move upwardly in the depending pipe 24 and correspondingly elevate the frame 18 with a sudden movement and cause the striker 27 on the stem 25 to forcefully contact with the gong or bell 28. At the same time the movement of the frame 18 causes the actuating dog or pawl 20 to pull the ratchet wheel 16 around the distance of one tooth against the resistance of the spring 17 and correspondingly move the index hand 13. This same operation will ensue until the desired number of signals are given, and a knowledge of the signal that was given can be reliably obtained by the engineer on inspection of the dial 112 so as to avoid mistakes as to desired direction of movement of the cage. Another advantage of this dial signal means is that should the engineer fail to hear the gong he can readily see by inspecting the dial 12 whether a signal has been given, and if he finds that the index hand 13 shows that a signal has been given he may at once respond thereto by operating his engine.
When the engineer sets the engine in motion in response to a signal he simultaneously actuates the plunger 35 in the dash pot 34 and releases the stop (log or pawl 29 from the ratchet wheel 16, and the latter is automatically returned to normal position by the spring 17 and the index hand 13 brought back to the zero point and ready for a succeeding signal which may be responded to at a proper interval.
From the foregoing it will be seen that many advantages will be present in the use of the improved signal apparatus, and that means are provided thereby for accurately informing an engineer, both audibly and visually, as to what movement of a cage operating in a mine shaft may be desired. The apparatus is comparatively inexpensive in its construction, and may be installed in operative position at a small expense.
Having thus described the invention, what is claimed, is:
1. A signal apparatus of the class set forth, involving visual and audible means, means for creating and transmitting a pneumatic impulse to the said visual and audible signal means for sinmltaneously operating the latter, means for automatically locking and temporarily holding the signal means in fixed position after movement, and means for simultaneously releasing both the visual and audible signal means :1. A pneumatic nal apparatus in combination with a. controlling motor or engine involvinga visual and audible signal means, the visual signal means being provided with a movable indicator to temporarily tixcdly register the signal given, pneumatic impulse creating and conveying means. and means for automatically restoring the parts of the visual indicating means to normal position simultaneously with the actuation of the controlling motor or engine.
3. I11 a signal apparatus of the class set forth, the coinbination of a visual indicating means having a dial with signal indicating characters thereon, and an index movable thereover, means for temporarily holding the index in fixed position on the dial, means for creating and transmitting a pneumatic impulse to the dial, and automatically controlled means for automatically releasing and restoring the index to normal position.
4:. A signal apparatus of the class set forth, having means for creating and transmitting a pneumatic impulse, the means for creating the impulse being disposed at different elevations, simultaneously operating visual and audible signal mechanism interposed intermediately with respect to the said means and actuated by either of the latter, an automatic controlling means for restoring the signal mechanism to normal position 5. A signal apparatus of the class set forth, involving simultaneously operating visual and audible signal mechanism, the visual portion of the latter comprising a dial having an index movable thereover, a ratchet element connected thereto, and means for locking the element against rotation beyond a predetermined point, piston means having a dash pot cooperating therewith for releasing the said locking means, the dash pot being operative from a controlling motor or engine, and devices for creating and transmitting a pneumatic impulse to the said visual and audible signal mechanism.
6. A pneumatic signal apparatus having a simultaneously operating visual and audible signal mechanism involving respectively a dial bearing indicating characters thereon, an index hand movable over the dial, a ratchet wheel connected to the dial, a movable frame for operating the ratchet wheel having a depending piston element and an upwardly projecting striker, a pipe into which the said piston element projects, a gong arranged above the dial for engagement by the striker, devices for creating and transmitting a pneumatic impulse to the pipe having the piston element therein, and mechanism for automatically restoring the parts of the visual indicating means to normal position simultaneously with the actuation of a controlling motor or engine.
In testimony whereof I have hereunto set my hand in presence of two subscribing Witnesses.
FRANK GOWIN.
Witnesses JOHN HOMER, GEO. W. Ennn'r.
US30646906A 1906-03-16 1906-03-16 Signal apparatus. Expired - Lifetime US867123A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US30646906A US867123A (en) 1906-03-16 1906-03-16 Signal apparatus.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US30646906A US867123A (en) 1906-03-16 1906-03-16 Signal apparatus.

Publications (1)

Publication Number Publication Date
US867123A true US867123A (en) 1907-09-24

Family

ID=2935573

Family Applications (1)

Application Number Title Priority Date Filing Date
US30646906A Expired - Lifetime US867123A (en) 1906-03-16 1906-03-16 Signal apparatus.

Country Status (1)

Country Link
US (1) US867123A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2646768A (en) * 1951-03-20 1953-07-28 Edwards Company Inc Gong construction and mounting

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2646768A (en) * 1951-03-20 1953-07-28 Edwards Company Inc Gong construction and mounting

Similar Documents

Publication Publication Date Title
US513601A (en) Mechanism foe conteolling engines
US867123A (en) Signal apparatus.
US2754788A (en) Fluid operated alarm system
US846305A (en) Combined train signal and indicating apparatus.
US745763A (en) Electrically-controlled motor-stopping apparatus.
US335934A (en) Signal system for telephone-exchanges
US80162A (en) Lobenzo fulton
US583326A (en) Engine stop mechanism
US469823A (en) Indicator for brake-pistons
US754847A (en) Audible alarm for air-braking systems.
US1010662A (en) Registering and indicating apparatus.
US1287927A (en) Engine-stop.
US406222A (en) lambinet
US1139948A (en) Automatic train-controlling device.
GB279189A (en) Improvements in or relating to signalling apparatus used in mines, shafts and like places
US623970A (en) Pneumatic-despatch apparatus
US1200454A (en) Automatic alarm for steam-gages.
US424450A (en) Engine
US410212A (en) smith
US228267A (en) Pneumatic annunciator
GB119514A (en) Improvements in Mine Signalling Apparatus.
US860165A (en) Water-governor for boilers.
US649523A (en) Signal.
US509459A (en) Indicating system
US802030A (en) Bell operating and controlling mechanism for blast-furnaces.