This is an extremely rare example of a first generation Buescher True Tone saxophone. Its estimated that this saxophone was manufactured in the late 1890's, before the banrupcy and reorganization which changed Buescher's name from The Buescher Manufacturing Company to The Buescher Band Instrument Company in 1904.
Buescher had completed many important experiments with the saxophone, using an original instrument from Adolphe Sax as a model. While a foreman with C.G. Conn, Buescher spearheaded the efforts there to produce the first saxophone in America circa 1887. While starting off on his own in 1894, it was a few years before Buescher started making saxophones for himself. Only about 1000-2500 Buescher saxophones were made under The Buescher Manufacting Company name.
These early Buescher saxophones feature soldered on tone holes and the older style double octave mechanism. As expected, they are nearly identical to the first series Conn saxophones. In 1901, Buescher saxophones were advertised at $40 for the soprano, $50 for the alto, and $98 for the bari sax, all in silver plate finish.
Note the unique engraving on this instrument. It is typical of gunsmith engraving. You see three distinct engraving styles represented here. There is "fern leaf" engraving which is the feather like engraving that spirals around and surrounds the Buescher name. There's "rose cut" engraving further out which is made with a wiggle & rotate action and used as a decorative fill for background space. Lastly, you also see "push cut" engraving which is done with a pushing motion where the engraver can angle left to right while pushing to make deeper or more shallow cuts. Push cut can be identified here as the more straight or slightly curved lines that you see in this engraving.