If you’re a rescue worker or boy scout, this illustration may not be what you are expecting, so to get the confusion out of the way first, there are two different ties called a French Bowline.
The French Bowline used in rescue work is a variation of the Simple Bowline, which forms two loops that can then be placed around a column (a body, or arm or leg).
In rescue work, one would be placed in the armpit and another around the thigh, or one around the body under the arms and the other as a seat, for hoisting a person. The weight of the person keeps both loops tight and prevents the person from falling.
You can see how that might be helpful in suspension bondage, and if you want to learn that tie, there is a clear step-by-step guide here
Another quick single-column French Bowline tie is illustrated on Wikipedia.
This tie is different again, and it’s elegance is that each of the rounds is threaded through the first loop, which means that when you pull on the standing end it will pull on the column with nice, even pressure.
It’s quick and easy to tie off at the end, and once is settles into position it won’t slip. It also only requires one running end, which makes it useful in the many situations when two running ends are not available.
There are many different single column ties, but this is a particularly nice one and will make you look like a professional.
• Two Knotty Boys (video) – The French Bowline Shackle