This section is from the book "A Treatise On Architecture And Building Construction Vol3: Stair Building, Ornamental Ironwork, Roofing, Sheet-Metal Work, Electric-Light Wiring And Bellwork", by The Colliery Engineer Co.. Also available from Amazon: A Treatise On Architecture And Building Construction.
11. A portion of the upper edge of the riser may be tongued into a groove in the under side of the tread, as shown at a in (a), Fig. it, instead of letting the whole thickness of the riser into the tread, as shown at (b). The lower edge of the riser may also be tongued into a groove in the upper surface of the tread beneath it, as shown at b in (a), in which case the tread would have to be nailed up into the riser as at c; this method, however, does not give as good results as that shown at a in (b).
The finished treads and risers are glued, and clamped together with handscrews until the glue has set. From two to four well fitted blocks are then glued and nailed to the internal angle of the tread and riser, as shown at b in (b). In Fig. 9 (b) are also shown the dovetails for inserting the balusters.