The stretchers on this table, I believe, are the element that has allowed it to survive as long as it has. They are low to the ground and cut into the legs. On the original they are nailed in place. Once in place they make the table quite stable. The stretchers are parallel to the ground and the legs are splayed which makes for angled cuts into the legs. I used a direct method to lay out the slots to be cut into the legs.
The first thing I did was mill the stock for the stretchers, then I marked the position of the stretcher on one of the legs. With the table sitting level on the bench I then cut a piece of scrap the height of the bottom of the stretcher. Using that piece of scrap I marked the bottom of the stretchers on all the legs.
Next using a small piece of the stretcher stock I marked the height of the top of the stretchers on all sides of all the legs.
One leg marked. The legs were marked with a knife I highlighted the knife cuts with a pencil for the photo, but not very straight. Using this method I was able to lay out the stretcher positions without doing any measuring or angle calculation.
After marking I sawed the slots for the stretchers.
Cleaned out the waste with a router plane.
Stretcher stock inserted into the slots in the legs.
With the stretcher stock in position I marked the miters. I used long clamps to make minor adjustments in the leg spacing while doing the marking.
All the miters cut and the stretchers glued in place. I used wood pegs instead of nails.