Appeal No. 98-0026
Application 08/536,304
the conduit. See ancient U.S. Pat. No. 77, 857,
granted to Young on May 12, 1868.
Cited in Mikkelson for this same principle are three other
patents which issued in 1891, 1894, and 1920. These are
consistent with the appellant’s information disclosure
statement
(Paper No. 2), wherein he cites U.S. Patent No. 501,744
(issued in 1893 to D.H. Streeper), in which steam is passed
through a flexible hose that is unreeled from a coil and “run
into the frozen pipe” to melt the ice, with the coil being
further unreeled and pushed into the pipe until it is
completely thawed out (page 2, line 41 et seq.). We therefore
view Mikkelson as being directed to improving upon the well-
known technique of applying heat to an ice blockage in a pipe
in order to melt it. A most important teaching presented in
Mikkelson is that of introducing the source of heat through an
aperture in the pipe through which water normally flows.
Regardless of the fact that Mikkelson teaches that the
apparatus disclosed also can be used to convey a suitable
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