Information is displayed in a stacked series of tubes of diminishing sizes that fit within each other, each tube being removable to allow the information held by the tube to be read separately. The system allows information to be displayed in a compact manner and is suitable for standing on tables etc.

A lens system for imaging infra-red radiation comprises two elements, one of Zinc Selenide and the other of either Zinc Sulfide or Cesium Bromide (5). Lens configurations are shown which allow imaging at a common image plane over at least both the 3-5 .mu.m and 8-12 .mu.m optical wavebands.

A detector for an alarm system receives a disturbance signal and transmits an alarm signal to a remote station. A group of such detectors can be connected in circuit to operate a common alarm. The detector has means (6, 26, 33) for suppressing a first disturbance signal so that only a second and subsequent ones trigger the alarm. There are also means (8, 30) whereby a disturbance signal only of a given length can pass to trigger the alarm. With another facility (38, 43) the detector registers wh...

A method of deploying a cable or other line in a fluid transportation pipeline while in normal operation full of and transporting a fluid under a positive pressure. A collapsible centralizing device is attached to the leading end of the cable and is then fed in a collapsed state into the pipeline via a first fluid sealing means at the cable entry position. That device maintains the cable end centralized in the pipeline cross section while the cable is fed into the pipeline. Magnetic sensing mean...

In an inductive communication system (11) in which transmit (16) and receive (18) aerials are in communication with a transponder (40), one of the aerials, e.g. the receive aerial (18), is arranged in two parts (61,62), one of the parts (61) being closely mutually-inductively coupled to the transmit aerial, and the other part being remote from the transmit aerial, so that the interference signal received by the receive aerial from the transmit aerial is substantially cancelled by the mutually in...

An indexing system made of a plurality of arranged index sheets, each provided with indicia such as a letter, color, or symbol on an extended area thereof and a plurality of holes so that when the sheets are arranged one on the other, a viewer can see the specific indicia through the holes.

A retaining wall comprises a facing, a counterfort connected to the rear of the facing, a footing supporting the facing and the counterfort, backfill behind the facing to provide a support surface for traffic, and a traffic barrier along the top of the wall. The counterfort comprises a reinforced concrete slab having a substantially vertical front portion at right angles to a base portion, and a rear portion running from substantially the top of the counterfort to the rear of the base portion th...

A vehicle security system can be fitted to a vehicle which has a radio transmitting device such as a cellular telephone, PMR or CB set. A control unit is arranged to periodically alert the driver of the vehicle to record a location message. When an alarm condition is signalled to the control unit from an alarm system, a panic button or a ratio receiver co-operable with a remote panic button transmitter, the control unit initiates a transmission from the radio transmitting device. The message tra...

A magnet system (1) for a nuclear magnetic resonance (NMR) imaging apparatus comprising a magnetic core arrangement (7, 13, 15) shaped to provide two or more discrete gaps (3, 5) of different sizes in which objects to be imaged may be placed, the magnetic field across each gap being produced by a single drive coil arrangement (9) associated with the core arrangement. A system providing gaps of different sizes, for different types of NMR examination is thus provided at relatively low cost compare...

A cable entry or exit pipe is formed on a fluid transportation pipeline while in normal operation full of and transporting a fluid under a positive pressure, by a method which comprises the steps: (a) producing two semi-cylindrical shells, one of which carries an oblique branch pipe and has an aperture aligned with the bore of the branch pipe; (b) securing in a fluid tight manner around the pipeline the two shells so as to form a reinforcing collar carrying an oblique branch pipe lying at an acu...