It's pretty endearing watching Watson helplessly attempt to coax the stick away from Nell, who clearly isn't having any of it, and who Holmes rather admires for her dedication to watching Watson plead so very insistently. He's almost chuckling when Watson finally turns to him, and he's certainly grinning widely, very proud of Nell.

"In that case, you ought to know that there's nothing to do but give up the chase." While Watson had been attempting to get the stick away from Nell, Holmes had spotted another one nearby; he picks it up and offers it to her, holding it up and making to throw it once or twice.

Nell at first is unsure. It has the smell of a trap, but it's also another stick, and it's about to escape, and if it does she had better be ready for it. Holmes watches her body start to tense, and by the time he finally throws it, Nell is ready to drop the hold on the current stick and run for the second. Holmes stoops to pick up the first and holds it out to Watson, smiling triumphantly.