US 476484 A
Description (OCR text may contain errors)
W. R. PATTERSON.
Patented June '7, 1892.
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(,6 Q4, We 1/ UNITED STATES PATENT OFFICE.
\VILLIAM R. PATTERSON, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE IVESTERN ELECTRIC COMPANY, OF SAME PLACE.
SPECIFICATION forming part of Letters Patent No. 476,484, dated June 7, 1892. Application filed October 29, 1891. Serial No. 410,241. (No model.)
T aZZ whom it may concern.-
Be it known that I, WILLIAM R. PATTER- SON, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois,have invented a certain new and useful Improvement in Cables, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawing, forming a part of this specifi- Io cation.
My invention relates to cables in which a core consisting of insulated conducting wire or wires is surrounded by a sheath of lead or similar material; and its object is to secure a I5 cable of low electrostatic capacity and at the same time one in which the sheath will not be liable to buckle when the cable is bent. It is well known that in order to make at cable of the lowest electrostatic capacitya large part of the insulating material. must be air and the core must fit loosely in the sheath. To accomplish this, a soft and yielding core is required, so that when a large cable so made with a soft and yielding core is bent,
as it is necessary to do in coiling it around manholes and in other similar situations, the pipe buckles to such an extent that it is impracticable to straighten it out without breaking the pipe. If, on the other hand, the core 0 is made hard and dense and the sheath fits the core tightly, the cable can be bent more readily; but the electrostatic capacity of the conductors is thereby increased and the electrical efficiency of the cable consequently diminished. To secure rigidityand atthesame time retain the soft core and the air-spaces, which are an essential feature of the lowcapaeity cable, I make the sheath with interior projecting longitudinal ribs, preferably integral with the sheath. These ribsbear against the core, leaving the spaces between the ribs filled with air.
A better understanding of my invention will be obtained by reference to the accompanying drawing, in which the pipe a has 5 upon its interior and running longitudinally with the pipe the ribs 1) b 7), preferably integral with the pipe and formed upon itsinner surface in the process of drawing the pipe. The air-spaces c c c are between outer serv- 5o ing (1 of the core 6 and the inclosing sheath or pipe, which is preferably formed of lead, or an alloy of lead.
Having thus described my invention, what I claim as new, and desire to secure by Let- 5 5 ters Patent, is
In an electric cable, the combination, with a core of insulated conductor or conductors, of an exterior metallic sheath havinginterior projecting longitudinal ribs in contact with the core, substantially as described.
In witness whereof I hereunto subscribe my name this 17th day of October, A. D. 1891.
IVILLIAM R. PATTERSON.
FRANK R. MCBEETY, GEORGE L. CRAGG.