<p>‘Whereby’ is a fairly commonly used word. It means “by which” or “through which.”</p>
<p>For example, you would say: “the best method is the method whereby you achieve the best results.” It is the method through which you achieve the most.</p>
<p>“The means whereby he took his life” = “The means through which he took his life”</p>
<p>All you have to do is use the dictionary. “Whereby” doesn’t fit in the sentence at all.</p>
<hr>
<p>The two clauses are:</p>
<p>1) Watermelons have been cultivated for more than 4000 years
2) Thumping watermelons to test for ripeness has an equally long history</p>
<p>The first clause implies that cultivating watermelons has a long history.
The second clause implies that thumping watermelons has an EQUALLY long history.</p>
<p>All you need is the conjunction “and” to connect them.</p>
<p>(1)Watermelons have been cultivated for more than 4000 years, and (2)thumping them to test for ripeness has an equally long history.</p>
<p>or</p>
<p>(1)Cultivating…has a long history, and (2)thumping…has an equally long history.</p>