Allen & Hall Alto Horn, Boston
Joseph Lathrop Allen probably came up with the idea for his
unique rotary valves with small diameter and flat airways
sometime around 1848.  This was the time that several German
craftsman were making Boston their home and likely were hired
by Allen to apply this technology to his new design.  These are
among the best quality brass instruments made at the time not
just in the US but Europe as well.  This alto horn was made
during a short partnership with David C. Hall in 1861.  For
more information about Allen see
Robert E. Eliason, Early
American Brass Makers, The Brass Press, 1979

The abused a deteriorated state of this instrument would negate
the wisdom of the restoration in most cases, but instruments by
Allen and Hall are extremely rare and valuable to collectors and
museums.  It was missing the mouthpipe,the entire tuning slide
assembly as well as all three valve levers and mounts and a few
other small bits.  The German silver that it is made of has
deteriorated to the point that not only are there numerous gaping
cracks but hundreds of hairline cracks.  A big challenge is to
remove dents as best as possible without causing additional
cracks.  Careful work was rewarded with very nice results.  
Some cracks were patched and others in the bell flare were
closed as much as possible and left.  Future owners will need to
handle this instrument with much care, which should certainly
be the case with all important historical instruments.  Accurately
reproducing the missing parts was possible using my notes,
sketches and photographs from past restorations of other
instruments of the exact model.  As bad as the rest looked, the
valve assemblies are actually in quite good condition and this
alto is an excellent player.