baber/WOPTO huggingface dataset:
Patent GB-1411616-A (GB)
Title: Preparation of olefin polymerisation catalysts
IPC: C08F4/00
Filed: 1972-11-17
Abstract: 1411616 Olefin polymerization catalysts SOC ITALIANA RESINE SIR SpA 17 Nov 1972 [27 Dec 1971] 53342/72 Heading C3P A catalyst for the polymerization of ethylene alone or copolymerization of ethylene with α- olefins is prepared by contacting an organometallic compound AlR 3 , AlR 2 X or ZnR 2  where R is a C 1 -C 4  alkyl group and X is halogen with the product obtained by impregnating in the absence of solvent a solid granular support, which is an activated sulphite of Ca, Mn, Mg or Zn, with a liquid halogenated derivative of a transition metal at a temperature of 50 to 160 C. for not less than 30 minutes the sulphite having been produced by (a) dissolving or suspending in water a Ca, Mg, Mn or Zn oxide, hydroxide or salt of an organic or inorganic acid with a pK of first acid dissociation exceeding 1.8 in a quantity of at least 5% by weight based on the weight of water (b) bubbling through the resultant solution or suspension having a temperature of 20 to 60 C., SO 2  in a quantity exceeding by 50 % at least that stoichiometrically necessary to transform the oxide, hydroxide or salt to a sulphite, (c) separating solid residues from the solution or suspension, (d) slowly eliminating unreacted SO 2  by slow agitation and by gradually lowering the pressure above the solution to a pressure corresponding to the vapour pressure of the solution at the elimination temperature which is substantially the same as used in (b) over a period of not less than 1 hour so as to precipitate a hydrated sulphite of Ca, Mg, Mn or Zn, (e) separating the precipitate from the liquid phase, washing it with a polar organic solvent and drying it at 20 C. at below atmospheric pressure for not less than 1 hour and (e) activating the sulphite at 350 to 750 C. for 3 to 25 hours in a flow of inert gas; the organometallic compound being in molar excess with respect to the transition metal on the support in the contacting step. The transition metal derivative may be TiCl 4  or VOCl 3 . In the examples magnesium hydroxide is converted to magnesium sulphite hexahydrate, which is activated at 400 C., granulated, impregnated with TiCl 4  and the product is used with AlEt 3  to continuously polymerize ethylene in heptane in the presence of hydrogen or to copolymerize ethylene with propylene or butene-1 in heptane.
Patent GB-1373101-A (GB)
Title: Magnetic recording and reproducing apparatus
IPC: G11B5/31
Filed: 1971-11-17
Abstract: 1373101 Head circuits; head construction HITACHI Ltd 17 Nov 1971 [2 Dec 1970] 53406/71 Heading G5R A signal S 1  to be recorded on a magnetic medium, e.g. disc or drum R, is converted into two signals of opposite polarity which are recorded on adjacent tracks by juxtaposed magnetic heads H 1 , H 2 . On playback, opposite polarity signals from the tracks R 1 , R 2  are recombined to form a reproduced signal, and noise which gives rise to same polarity signals in the magnetic heads H 1 , H 2  is thereby eliminated. Recording/playback utilizes a transformer T 1  having oppositely-wound secondary windings W 21 , W 22 , while erasing utilises a transformer T 2  having similarly-wound secondary windings W 21 , W 22  to apply same polarity signals to the heads H 1 , H 2 . Magnetic heads.-The heads H 1 , H 2 , Fig. 3, are preferably manufactured as a pair from thin films laid down by evaporation, electrodeposition, &c. A base member 21 of insulating material, or having an insulating surface covering, carries two magnetic cores 23, 24 each formed from two laminations 231 (232), Fig. 4 (not shown) and 241, 242 of magnetic films defining gaps 233, 243, and an E-shaped winding 22 of conductive film which constitutes two singleturn windings having a common link 223. The winding 22 is insulated from the magnetic cores 23, 24 by films 25, 26. The magnetic characteristics of the cores 23, 24 may be made equal by imparting anisotropy to the laminations. The hard axis of magnetization may thus be made to coincide with the flow direction of magnetic
Patent GB-1195654-A (GB)
Title: Polyol Blends
IPC: C08G18/67
Filed: 1968-11-12
Abstract: 1,195,654. Bicyclo - [2,2,1] - heptene derivative. UPJOHN CO. 12 Nov., 1968 [11 Dec., 1967], No. 53500/68. Heading C2C. [Also in Division C3] The tetrol of formula is prepared by esterification of 1 molar proportion of 1,4,5,6,7,7-hexachlorobicyclo[2.2.1]-5- heptene-2,3-dicarboxylic acid with 2 molar proportions of trimethylolpropane.
Patent GB-1403728-A (GB)
Title: Parenteral fluid flow controllers
IPC: A61M5/168
Filed: 1972-06-14
Abstract: 1403728 Infusion apparatus SCI SYSTEMS INC 14 June 1972 [25 June 1971] 54068/74 Divided out of 1403725 Heading A5R The subject-matter of this Specification is identical with that of the parent Specification 1403725 but the claims relate to an intravenous fluid flow controller comprising a conduit including a drip chamber a magnetic valve within the conduit and magnetic means outside the conduit for actuating the valve at least once for every drip in the chamber.
Patent GB-1329741-A (GB)
Title: Powdered polymide compositions
IPC: C09D5/03
Filed: 1970-11-18
Abstract: 1329741 Laminated fabric E I DU PONT DE NEMOURS & CO 18 Nov 1970 [18 Nov 1969] 54834/70 Heading B5N [Also in Division C3] A powdered polymer composition comprising polyamide and an alcoholysed ethylene/vinyl ester copolymer is prepared by grinding the polyamide in the presence of the copolymer. The polyamide may be derived from a C 6-20  linear diamine and a C 2-48  linear dicarboxylic acid or a C 4-18  omega amino acid; it may be a copolymer of nylon 6 with 66 and/or 610, 611 or 612 having a melt index of 0À1 to 100 and a melting-point below 170‹ C., which would be difficult to grind in the absence of the alcoholysed copolymer. The copolymer may be derived from 70 to 98 mol. per cent ethylene and 2 to 30% vinyl formate, acetate, propionate, butyrate, palmitate or stearate by high pressure or catalytic polymerization using a free radical, ionic or Ziegler catalyst and should be 50 to 100% alcoholysed; it may be used in an amount of 1 to 100 wt. per cent related to the polyamide. Laminating fabrics.-A coating of the powdered composition of average diameter 20 to 1000 microns is applied to textile material and heated above the melting point. A second textile material is then ironed on to the first piece.
Patent GB-1236937-A (GB)
Title: Gas flow switching for chromatographic columns
Inventor: DEANS DAVID ROBERT
IPC: G01N30/46
Filed: 1967-12-01
Abstract: 1,236,937. Gas flow switching systems for gas chromatography. IMPERIAL CHEMICAL INDUSTRIES Ltd. 18 June, 1968 [1 Dec., 1967], No. 54866/67. Heading B1L. A gas flow switching process enabling the effluent from column 4 to be switched to trap 8 and thereafter from trap 8 to column 11 comprises passing the stream of carrier gas to both pressure controllers 1 and 12, the pressures being adjusted so that there is no flow in limb 7 when valves 2, 9 and 13 are open and valve 16 closed. Sample is injected at 3, separated in column 4, and an effluent fraction as desired trapped in cold trap 8. To pass the trapped effluent for further resolution in column 11, trap 8 is warmed, needle valve 15 appropriately adjusted and valve 16 opened. In other embodiments, two parallel cloumns (25, 26) are positioned downstream of a first column (23) so that the effluent from the first column may be switched as desired to one or other of the downstream columns (see Fig. 2, not shown); and three parallel columns (55, 56, 57) are situated downstream of first column (53) for similar reasons (see Fig. 3, not shown).
Patent GB-1444720-A (GB)
Title: Pipelines
IPC: F16L9/12
Filed: 1972-12-01
Abstract: 1444720 Reinforced plastics pipe; insulated ISLAND INTERNATIONAL ENGS Ltd 29 Nov 1973 [1 Dec 1972] 55708/72 Heading F2P A pipe-line comprises an internal resilient tubular membrane 1 of plastics material, e.g. P.V.C. around the outer surface of which are provided longitudinally extending wires 2, around which is coiled a second wire 3, said wires preventing rupture of membrane 1 under internal pressure and being covered by heat insulation 4, e.g. polyurethane or cork which in turn is covered by a protective layer 5 of plastics material, e.g. P.V.C.
Patent GB-1447940-A (GB)
Title: Construction and propulsion of ships for carrying oil or bulk  cargoes
IPC: B63H5/02
Filed: 1974-12-24
Abstract: 1447940 Tankers; paddle wheels A P PEDRICK 24 Dec 1974 55800/74 Headings B7A and B7V [Also in Division B8] A ship, has, extending substantially throughout its length, a vertical water-tight frame member 3 rigidly secured to the base structure and to its upper deck structure to provide an I-section girder and has chambers bounded by the frame member, the base structure and the upper deck structure adapted to receive containers floatable into and out of these chambers. The ship has a floodable bow 4 to adjust for and aft trim and carries tanks, containers A to H (e.g. for oil) or smaller navigable vessels, Fig. 4, not shown, and has near the bow telescopic hydraulically or pneumatically operated hull parts 14<SP>1</SP>, 14<SP>11</SP> for berthing. Propulsion is by means of two paddle wheels 10<SP>1</SP>, 1011 rotating about vertical axes inside longitudinal shields. Flow deflectors 12<SP>1</SP>, 12<SP>11</SP> are operated by transverse pneumatic or hydraulic pistons 13. A boiler and turbine, Fig. 1, not shown, or a diesel engine 7, 8, on either side of the frame member 3 drive individually, or in unison, the wheels 10<SP>1</SP>, 10<SP>11</SP> via a transverse shaft 20 which extends through the member 3.
Patent GB-1376928-A (GB)
Title: System for illuminating the travelling path of a vehicle and protecting the driver from dazzling
IPC: F21S8/10
Filed: 1971-12-01
Abstract: 1376928 Laminated anti-dazzle system BATTELLE MEMORIAL INSTITUTE 1 Dec 1971 [10 Dec 1970] 55842/71 Heading B5N [Also in Divisions B7 F4 G2 and H1] An interference line filter, for an anti-dazzle vehicle lighting system (see Division F4), either in the form of a screen or spectacles comprises, Fig. 3, a MgF 2  interference layer 12 disposed between two partially permeable reflector layers 13, 14 of silver which in turn are provided with a support plate 11 and a protective transparent layer 15 of SiO 2 . In a further embodiment, Fig. 5, the cryolite (Na 3 AlF 6 ), interference layer 18 is sandwiched between similar reflection systems 19-25 and 26-32. Layers 19, 21, 23, 25 and 26, 28, 30, 32 are formed of TiO 2  or ZnS and the intermediate layers 20, 22, 24 and 27, 29, 31 are formed of cryolite, MgF 2  or SiO 2 . In the examples respective thicknesses and refractive indices of the various layers are given.
Patent GB-1330185-A (GB)
Title: Enamel for coating aluminium ware
IPC: A47J36/02
Filed: 1970-11-24
Abstract: 1330185 Vitreous enamel composition OBERSCHWABISCHE METALLWARENFABRIK GmbH & CO KG 24 Nov 1970 [27 Nov 1969] 55888/70 Heading C1M An enamel has a composition in which cadmium, zinc, barium, strontium and lead oxides are all absent and contains in percentages by weight SiO 2  25-50; TiO 2  10-35; R 2 O 20- 40; Bi 2 O 3  2-15; B 2 O, 0-10; Al 2 O 3  0-7; SnO 2  0-15; CoO 0-5; NiO 0-5; MnO 0-5; CuO 0-5 and FeO 0-5; where R represents one or more alkali metals. The enamel is particularly useful for coating those surfaces of aluminium or aluminium kitchenware which come into contact with foodstuffs.
Patent GB-1146430-A (GB)
Title: Improvements in and relating to encapsulation
IPC: B01J13/08
Filed: 1966-03-04
Abstract: 1,146,430. Forming microcapsules. KEUFFEL & ESSER CO. 4 March, 1966 [5 March, 1965], No. 55907/68. Divided out of 9697/66. Heading B8C. Microcapsules are formed by dispersing the core material in a solution of vinyl acetate unsaturated acid copolymer and adjusting the pH value to precipitate the polymer round the core material. The solution is aqueous. Typical copolymers may contain up to 15% crotonic, maleic, acrylic or similar acids. Cores may be solid or liquid. A solution of the copolymer with an antifoaming agent such as silicone and an emulsifying agent such as triethanolamine is formed and the core material, e.g. an oil and dye are mixed to produce the emulsion and the pH lowered by addition of an acid with continuous stirring. The capsules are filtered out and may be hardened, e.g. with formaldehyde. As one of a number of examples given, three solutions are prepared. (A) 10 g. of the copolymer 1 ml. triethanolamine 75 ml. sodium hydroxide (I.O.N.) 225 ml. water 2 drops silicone anti-foaming agent (B) 30 ml. carbon tetrachloride 2 g. diphenylamine (C) 30 ml. hydrochloric acid (I.O.N.) An emulsion was prepared by agitating solutions A and B together with a high speed stirrer until the desired droplet size was obtained. Solution C was slowly added with stirring to form the shells.
Patent GB-1486194-A (GB)
Title: Olefine polymer olefine polymerisation process and catalyst
IPC: C08F10/00
Filed: 1973-12-04
Abstract: 1486194 Polymerization catalysts; propylene polymers IMPERIAL CHEMICAL INDUSTRIES Ltd 4 Dec 1974 [4 Dec 1973 28 March 1974] 56168/73 and 13741/74 Heading C3P An olefin polymerization catalyst comprises (a) a solid component containing TiCl 3  and having a specific surface area of at least 50 m.<SP>2</SP>/gm., (b) an organometallic compound, (c) a Lewis base, and optionally (d) a polyene, preferably cyclic. Component (a) is prepared by reducing TiCl 4  with an organo-aluminium compound, separating the reduced solid from the reaction medium, treating the solid with a complexant which is an ether, thioether or thiol, separating off any excess complexant, contacting the treated solid with TiCl 4 , and isolating the resulting TiCl 3  component. The Lewis bases (c) are defined as cyclic amines, diamines, alkanolamines, amides, ureas, esters and ketones and thioanalogues thereof, silanes, siloxanes, and organic phosphorus compounds, e.g. phosphites, phosphates, phosphines, phosphine oxides and phosphoric amides. Polymers of propylene obtained using these catalysts usually contain, without purification, not more than 60 p.p.m. of Ti and not more than 250 p.p.m. of halogen, and exhibit a flexural modulus of at least 1 GN/m.<SP>2</SP>. Examples refer to the homopolymerization of propylene in a diluent, in liquid monomer or in the gas phase using preformed polypropylene carrier, usually in the presence of hydrogen, and in the presence of (a) the TiCl 3  obtained by reacting TiCl 4 /Et 3 Al 2 Cl 3  or Et 2 AlCl, separating, complexing with diisoamyl ether, and reacting with further TiCl 4 , (b) Et 3 Al or Et 2 AlCl, (c) tetramethylethylene diamine, hexamethylphosphorictriamide, N,N,- N<SP>1</SP>,N<SP>1</SP>,N<SP>11</SP> - pentamethyl - N<SP>11</SP> - # - dimethylaminoethyl phosphoric triamide, octamethylpyrophosphoramide, γ - picoline, 2 - dimethylamino - 1,3 - dimethyl - 1,3,2 - diazophospholidine - 2 - oxide, triphenylphosphine oxide, or 2,4,6,7 - tetramethyl - 2,6,7 - triazo - 2 - phospholidino - [2,2,2] - bicyclooctane - 2 - oxide, and (d) cyclooctatetraene or 1,3,5-cycloheptatriene. In some cases the porosity of the component (a) and the particle size distribution of the polymers produced are given. Reference has been directed by the Comptroller to Specification 1,391,068.
Patent GB-1371976-A (GB)
Title: Process for d- - -mepivacaine
Inventor: AF EKENSTAM B T
IPC: C07D211/60
Filed: 1972-12-06
Abstract: 1371976 Process for D-( - )-mepivacaine BORFORS AB 6 Dec 1972 [6 Dec 1971] 56296/72 Heading C2C [Also in Division A5] The invention comprises a process of preparing D-( - )-mepivacaine, or a pharmaceutically acceptable acid addition salt thereof, which comprises the steps of: (a) replacing the active hydrogen of the -NH group of D-( + )-pipecolic acid with the carbonylbenzyloxy group; (b) reacting the protected D-( + )-pipecolic acid formed in step (a) with iso-butyl chloroformate, (c) reacting the product of step (b) with 2,6- dimethyl aniline; (d) reducing the product of step (c) with hydrogen to eliminate the carbonylbenzyloxy group; (e) N-methylating the D-( - )- pipecolic acid-2<SP>1</SP>,6<SP>1</SP>-xylidide formed in step (d) to produce D-( - )-mepivacaine, and, if desired, (f) forming a pharmaceutically acceptable acid addition salt of D-( - )-mepivacaine.
Patent GB-1292647-A (GB)
Title: Latch opening apparatus for knitting machines
Inventor: FLAD KARL
IPC: D04B15/28
Filed: 1969-11-18
Abstract: 1292647 Knitting-machine K FLAD 18 Nov 1969 [27 Nov 1968 21 Oct 1969] 56423/69 Heading D1C A latch opener for a parallel or circular machine comprises a permanent magnet, or d.c. energised electro-magnet moving across the needle bed(s) with the cam carriage or stationarily positioned across the full width of the beds, and means for supplying an alternating field for demagnetising the latches. Demagnetisation may be achieved by energising the magnet with an a.c. supply on alternate traverses. Alternatively two magnets may traverse the beds and a switching arrangement may be provided to ensure the a.c. energised magnet precedes the d.c. or vice versa. If a traversing permanent magnet is used it is placed between a.c. demagnetising electromagnets. If a magnetising rail is provided along the machine demagnetisation occurs when the carriage is at the end of the bed. The needle bed may be demagnetised by a coil attached to it; or may be of non-magnetic material. The needle bodies may also be of non-magnetic material; the bodies, hooks or latch depressions may be chromium plated.
Patent GB-1281555-A (GB)
Title: Improvement in and relating to hydraulic overload safety devices for presses
Inventor: HARTUNG WOLFGANG
IPC: B30B15/28
Filed: 1969-11-19
Abstract: 1281555 Hydraulic safety devices for presses PRESSEN-UND SCHERENBAU ERFURT VEB 19 Nov 1969 56664/69 Heading F1P A hydraulic overload safety device for a press comprises a hydraulic cushion 6, Fig.2, for each pressure transfer point (two of which are shown) and each cushion 6 is connected by a duct 9 to an associated control unit 10 and by a common duct 15 to a compressed air operated hydraulic pump 13 drawing at 14 from a tank 12; each control unit 10 having a control plunger 21, Fig.1, subjected at its lower end to cushion pressure transmitted through duct 9 and having a closure valve 18 also subjected to cushion pressure in duct 9 and acting against a closure spring 17 together with pump delivery pressure in duct 15 transmitted through ducts 19, 20, 38 the arrangement being that on a predetermined rise in cushion pressure at 6 control plunger 21 lifts to connect the underside of valve 18 and also connect the pump delivery duct 15 through ducts 19, 20, 38, 39, 40, 11 to the tank 12, and at the same time valve 18 opens to connect cushion 6 to duct 11 and tank 12. The control plunger 21 on being lifted operates a limit switch 28 to stop the pump 13. An adequate initial cushion pressure is indicated by closure of a limit switch 35 by the rod 33 of a piston 32 when moved by cushion pressure against a compressed air loading pressure admitted at 30.
Patent GB-1153050-A (GB)
Title: Improvements in or relating to Magnetic Records
Inventor: MCKEE FREDERICK BRIAN
IPC: H04L13/08
Filed: 1966-12-23
Abstract: 1,153,050. Electromagnetic printing. MARCONI CO. Ltd. 28 Sept., 1967 [23 Dec., 1966], No. 67655/66. Heading B6C. [Also in Division G5] A magnetic record 1 runs over a supply of ferro-magnetic or ferri-magnetic powder, placed on a sheet or tray 14 and subjected to a lowintensity constant magnetic field so that it adheres to the record 1, and is then brought into contact with a record member 8, e.g. damp photographic film, to which the powder is transferred and adheres mechanically. Preferably the sheet or tray 14 is vibrated and has a permanent magnet 15 mounted adjustably beneath it, and the magnetic powder contrasts in colour with the surface of the record member 8. If the magnetic record 1 is in the form of a closed loop of tape driven past a recording head 18, it is cleaned and erased at 19 and 21 between contact with the record member 8 and further passage past the recording head 18. It may previously be illuminated by light sources 20, a small proportion of fluorescent powder preferably being mixed with the magnetic powder.
Patent GB-1211209-A (GB)
Title: Improvements in and relating to frame structures
Inventor: BOGGIO F GEORGE
IPC: B30B15/04
Filed: 1967-12-21
Abstract: 1,211,209. Press frames. BAROGENICS Inc. 21 Dec., 1967 [3 Jan., 1967], No. 58037/67. Heading B5F. [Also in Division B3] A frame structure particularly for a forging or extrusion press comprises at least two frames 20, 20<SP>1</SP>, Fig. 2, each of which comprises oppositely disposed crossheads 22, 24 and 22<SP>1</SP>, 24<SP>1</SP> coupled together by tie means 26, 28 and 26<SP>1</SP>, 28<SP>1</SP>, the end portions of the crosshead members of at least one of the compound crossheads 22, 22<SP>1</SP> being in overlapping relationship. In one embodiment, Fig. 2, each frame is identical and comprises a pair of spaced upper and lower crosshead beams coupled together through hinge pins by spaced tie beams. Each crosshead beam and tie beam may be independently jointed so that each frame 20, 20<SP>1</SP> is formed of two independent frames. The frames 20, 20<SP>1</SP> are arranged in interleaving and overlapping relationship with one another, the crosshead beams being formed with openings (23, 25) and 23<SP>1</SP>, 25<SP>1</SP> to receive the ends of the tie beams. In another embodiment, Fig. 6, a frame, comprising preferably single upper and lower crosshead beams 52, 54 having depending portions 53, 55 coupled through pins to tie beams 56, 58, is interleaved and overlapped with a frame comprising spaced upper and lower crosshead beams 52<SP>1</SP>, 54<SP>1</SP> having depending portions coupled through pins to spaced tie beams 56<SP>1</SP>, 58<SP>1</SP>. In a further embodiment, Fig. 10, the tie beams 83, 88 of each frame 80 are joined to crosshead beams 82, 84 by pins passing through plates 83, 85, 87, 89. The pins (92), (97), 90<SP>1</SP>, 95<SP>1</SP> respectively passing through the plates 83, 85, 87<SP>1</SP>, 89<SP>1</SP> may also pass through the beams of the adjacent frame in order to interlock the frames 80, 80<SP>1</SP>.
Patent GB-1244263-A (GB)
Title: Apparatus for cleaning paper webs
Inventor: GROSSHAUSER HEINRICH
IPC: B41F23/00
Filed: 1969-12-01
Abstract: 1,244,263. Printing apparatus. SCHNELLPRESSENFABRIK KOENIG & BAUER A.G. 1 Dec., 1969, No. 58576/69. Heading B6C. Dust and dirt on a paper web 1 travelling to a printing machine is subjected to electric discharge by elements 23, prior to being blown from the web into discharge conduits 16, 17 by air jets 9 and 10. The housing accommodating the discharge elements and air jets is made in two parts which are swingable away from the web about pivots 5, 6.
Patent GB-1332599-A (GB)
Title: Air line lubricators
IPC: F16N7/34
Filed: 1971-12-17
Abstract: 1332599 Mixing by sonic waves PARKERHANNIFIN CORP 17 Dec 1971 [5 Jan 1971] 58718/71 Heading B1C An air line lubricator has an air passage 7 within which is a said wave generator 26 (as shown, a whistle 27) to which lubricant is delivered through a dip-tube 20, metering valve 16, sight glass 22 and tube 23. The whistle tube has a plugged end 28 and triangular side opening 30, and the lubricant is delivered to it partly by excess pressure in the bowl 11 generated by the upstream facing entrance 25 of the tube 24, and partly by induction through the downstream facing end of tube 23. The whistle causes dispersion of the lubricant in the air stream. In modifications the whistle tube 27 may be formed as a venturi and the tube 23 terminate flush with its throat (see Fig. 2, not shown); the air passage 7 may be venturiform in the region of the aperture 30 (see Fig. 3, not shown); the size of the aperture 30 may be adjustable by a threaded sleeve (43, Fig. 4, not shown); the tube 23 may enter the whistle tube opposite the side aperture (see Fig. 5, not shown); the frequency and particle size may be controlled by making the whistle tube length adjustable by means of a threaded end plug (56, Fig. 6 not shown); the whistle tube may be open at both ends (see Fig. 7, not shown). Alternatively the whistle tube may be replaced by a reed or other device.