Spiral staircase

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Description

FIG. 1 is a front, left side perspective view of the design for a spiral staircase;

FIG. 2 is a left side elevation view thereof;

FIG. 3 is a front elevation view thereof; and,

FIG. 4 is a top plan view thereof.

Claims

The ornamental design for a spiral staircase, as shown.

Referenced Cited
U.S. Patent Documents
D271524 November 22, 1983 Suckno
6155007 December 5, 2000 Murase
6523310 February 25, 2003 Tseng
Patent History
Patent number: D673691
Type: Grant
Filed: May 26, 2011
Date of Patent: Jan 1, 2013
Inventors: Piero Alessandrini (Rome), Chiara Alessandrini (Rome)
Primary Examiner: Doris Clark
Attorney: Young & Thompson
Application Number: 29/392,782
Classifications
Current U.S. Class: Stepped (12) (D25/63)