Vacuum Cleaner
a mechanical device for getting rid, by means of air suction, of dirt and dust from the floors and other parts of a house. It consists in the main of a nozzle which is run over the area that needs cleaning, a pipe connecting the nozzle with a separator where the dust and dirt are removed from the air, and an exhausting apparatus for producing a vacuum. The nozzles are in such shapes and sizes as the work may require. Some vacuum cleaners are operated by current which is derived from connection with a lamp socket. Another of a more extensive kind, mounted on a carriage and driven by an internal combustion engine, is stationed outside the building to be cleaned and the hose passed through the window. The third ssed throu type is located as a rule in the basement of a building and is connected by permanent pipes with outlets to which nozmammals, such as the Ornithorhynchus, opens into cloaca, while in the kangaroos and other Marsupialia it opens into a canal named the uro-genital canal, which receives the efferent ducts of the urinary organs. In higher quadrupeds the vagina is distinct both from the rectum and the urinary ducts. In the human subject it attains a length of about four inches measured along its anterior wall and six inches measured on its posterior surface. It lies between the bladder and rectum; constricted at its commencement it becomes dilated toward its uterine end. The coats of the vagina number three-an external or muscular layer, a layer of erectile tissue, and an inner or mucous layer. The mucous layer is thrown into folds or rugæ, which permit the distension of the canal in the process of parturition.