In 1910 by Charles Jacobus of Springfield, Massachusetts, patented the insert system built into the face of this driver.  According to his patent, the three wood dowels were placed "substantially parallel with the direction of the stroke, or at right angles to the grain of the head itself."  The longer side inserts were installed prior to drilling out the cavity for the shorter and wider middle insert—so the inner end of the middle insert would rest "against the shoulders formed on the other two parts."  Jacobus believe his face insert system would be more effective at standing up to the forces at impact. 

Jacobus assigned his patent to Spalding, which made the dowels out of mahogany. Spalding offered this design between 1913 and 1923, as it proved to be reasonably popular.

This is a solid example with a clean face and its original shaft, grip, and brass backweight.  For more on this club, see TCA2 v2 p403.

This club, likely made for a lady golfer, still has its 41" original shaft and leather wrap grip.