Answer: experimental steps: pour a proper amount of water into the wellbore and measure the liquid level height of water H 1;

Float eggplant in a well tube, and measuring that wat level H2;

Dip eggplant into water with a pencil tip and measure the water level of H3.

Eggplant floats in the water, the gravity of eggplant is equal to the buoyancy of eggplant, and the buoyancy of eggplant is equal to the gravity of eggplant drainage.

Therefore, G=F float =G row = ρ water gvrow =ρwater gS(h2-h 1) (let the bottom area of the wellbore be s),

So the quality of eggplant is: m=Gg=ρ water gS? (h2-h 1)？ G =ρ rho water S(h2-h 1),

The volume of eggplant is v=S(h3-h 1),

The density of eggplant is ρ=(h2-h 1)ρ water H3-H 1.

So the answer is: (H2-h1) rho water H3-H 1.