Looking at your drawing, I assume you mean the lashing between the bowsprit and the jib-boom.
You see that the spars are spaced by the bowsprit cap. There is also a chock or spacer at the foot of the jib-boom so the spars are parallel.
In this case there are two lashings, also called cruppers or sometimes woodlings. They are made by simply wrapping a rope around both spars seven or eight times, then tightened by wrapping a few turns (4 or 5) around the first ones between the spars.
The whole is stopped by simple half hitches.
There are a lot of other possible arrangements, and the drawing you show appears to be of quite a small vessel. I confess the lashing appears much smaller and single in most illustrations from my rigging manuals.