a proper ''western union'' splice or staggered WU splice (two + wires)
http://www.tpub.com/content/neets/14176/css/14176_46.htm is to bring the stripped wire butts 1/2 way together and wrap each side round the other. solder. tape
i now use heat shrink
it works for solid and stranded, got it's name from . . . . you guessed it right
the railroad telegraph, 1861 Western Union completes the first transcontinental telegraph line, providing fast communications during the Civil War.
more insane railroad trivia
SPRINT
stands for
S outhern P acific R ailroad I ntigrated N etwork T elecommunications