Abstract: Brush gear for electrical machinery comprises a brush movably mounted on a support and a flexible housing which connects the brush with the support and contains a quantity of liquid metal to form a current flow path between the brush and the support. The brush, which is preferably composed of resilient fibres, may be adjustable by a positive drive mechanism, the necessary movement being permitted by bellows walls or diaphragms forming the housing.

Abstract: A photo-voltaic hetero-junction is formed by chemical conversion of surface regions of a sheet of one conductivity type into material of a second conductivity type, the areas which are not to be converted being covered by a developed photo-resist layer which has previously been exposed to light through a mask. Electrical contacts are deposited on the regions of the second type and contacts to the material of the first type are formed by a layer deposited on a substrate under the sheet of material of the first type. This deposited layer of electrically-conductive material can also form the mask for initial exposure of the photo-resist layer.

Abstract: In a method of explosively welding a metal pipe into a bore in another metal member, such as tube plate or another pipe, the explosive charge is surrounded by a body of impacting medium which is spaced from the inner surface of the pipe wall so that upon detonation of the explosive the impacting medium reaches a high velocity, without disintegrating, before it strikes the pipe wall to effect expansion thereof.