Maxwell-hosel irons are characterized a pattern of holes drilled into the hosel.  This design was the brainchild of Ben Sayers and covered under a Briitish design registration issued to Sayers on Sept 18, 1909.  The idea was simply that of moving weight out of the hosel and into the blade. This example has a flange on the sole which is a rarely seen on an antique hickory shaft iron.

Maxwell irons had issues, however.  If the wood exposed in the hosel became wet the shafts were liable to rot, though efforts were occasionally made to prevent such deterioration.

Measuring 36 1/2" in length and marked "Special Niblick" along with the owner's "K" initial on the back of the blade, this is a fine all-original example of a Maxwell iron with a leather wrap grip.  TCA2 V2 p451 presents an iron with a Maxwell-style hosel and provides more historical information.