Apparatus for Electrically Measuring the Height or the Pressure of Fluids at a Distance

20,056. Perret, D. Sept. 9, 1905, [date applied for under Patents Act, 1901]. Water-level indicators.-An apparatus for electrically measuring the level of a liquid at a distance consists of a manometrical column of conducting-liquid such as mercury, the variation of the height of which causes a corresponding variation in the readings of an ammeter, in series with aresistance acted on by the liquid conductor, so that the resistance is increased as the level rises, and variations of level of the liquid when low produce greater variations in the indicating-instrument than equal variations at higher levels. In the form shown, the reservoir communicates by a pipe b with a U-tube d containing mercury. A bare copper wire e and a highresistance wire e are supported on an insulating- rod e in the arm of the tube d , which is in connexion with the reservoir, and are connected in series with a battery and ammeter. The other arm of the U-tube may be connected with a widened part d or may be closed. Instead of the rod e and resistance wire e , the mercury column may be arranged to connect in parallel successive resistances, connected to contacts inserted through the U-tube. In modifications, the resistance wire e may be wound spirally on the rod e, the pitch of the spiral increasing as it ascends, or the leg of the tube containing the rod may be arranged obliquely. The Specification as published under the Act of 1901 describes modifications in which a single tube dipping into a reservoir of mercury is used, and in which the resistance is decreased as the level rises and in which the manometric column is immersed in the reservoir, and also states that the scale of the ammeter may be graduated in levels. This subjectmatter does not appear in the Complete Specification as accepted.