Oh and that too. 
That requires a little common knowledge. Google can’t do it for you. 
He is not making this up.
Here is a link for it and look on page 5.
Haven’t seen this type of stair build in decades.
He must have read about it. Doubt if he evever built stairs like it. :)
Mortise and ploughed rabbit for wedge insert.
And here;
http://buildingownhouse.com/stairs/30-building-finish-stairs.html
**Glue and wedges lock the stairs together
**
With the housed stringer on a flat floor, I put the bottom tread and riser tight together in their mortises. I squeeze enough glue behind the riser to cover both sides of the wedge. Glue holds the stairs together and keeps them from squeaking. I use lots and don’t worry about squeeze-out here; it will be hidden. While keeping the riser seated in its mortise, I hammer in the wedge until its butt starts to splinter. Then I pull the tread out and install the rest of the risers the same way. The treads go in later.
Keeping the risers and treads seated in their mortises is crucial. Their square cuts are what keep the stairs square.
The next step is easier with a helper, but not impossible alone with a nail gun. I nail the mitered stringer to the risers with 1 in. finish nails through the miters. It isn’t necessary to glue the miters. Glue blocks from behind will reinforce them with little chance of glue dripping on the finished surfaces. I keep the joints between the risers and stringer flush; otherwise, the returns on the treads may not fit tightly to the stringer. It’s easiest to sand these miters before installing the treads.
Next, I run a bead of glue down the back of the first tread. I stay toward its bottom to minimize squeeze-out; it will show here. I put the nose of the tread in the mortise with its other end flat on the notch and rotate the tread into place. I check that the overhanging end on the return fits tightly to the mitered stringer. If it doesn’t, I remove the tread and trim some from the housed end. Bracing the stringer with my body, I drive 8d finish nails through the tread into the mitered stringer, being mindful of where I’ll later drill for balusters. Moving to the housed stringer, I spread glue in the mortise and then wedge the tread in place.
I see that Marcel but I don’t think it has anything to do with the picture in post #1
And they call out a wedge in your posted diag. but don’t show it.
He may have read it but he couldn’t come up with when asked.
Although the wedge is not there in that picture, believe me, they were used, I seen them. Those pictures are hard to find.
Post #1 did not use wedges for it’s construction. 
Actually the one in the picture is new and yes it had the wedges. Some contractors are still doing it here and the one that went to the dump was 28 years old. It could not be saved.
Kevin, the pictures posted are of two different stairs in post #1.
The first stair would not have wedges. The treads slide in to the rabbetted groove and glued and screwed or nailed.
The second picture is a closed stairs where the treads could be mortised and the wedges are used to tighten the joint between the tread and the riser and mortised joint.
I believe you Marcel. I understand that construction method.
My point was that KEVIN was speaking about those stairs in post 1 with no understanding, just something he may have read in a book.
And the pics in post 1 are both the same stairs.
I am talking about my picture Marcel! I find this is big problem on the MB unless you read every post and now who is responding to who.
I guess I should use the quote button more often.
Duh! :roll::roll:
That being said I have seen both designs and both with wedges.
BS KEVIN WOOD
Your post 8 was talking about post 1
Why lie?
Well if you are talking about this poor picture of a winding stair that is unsafe and don’t meet safety standards, it is a poor example, I am afraid.
Don’t even have a railing on the right side.
There should only be 3 pie shapes in the winder to get a 10" tread away from the axis.
Hope you noted all of that. ;)
Yes It was a very bad example Marcel. Nothing was correct.