<p>The radiation emanating from the Sun has been very nearly constant for millions of years, but the amount of heat that falls on Earth’s surface (depends on both the length of the period of daylight as well as on) the angle of incidence of incoming sunlight.</p>
<p>In the sixteenth century, (the forests were destroyed in Britain, which meant not only a shortage) of the most important building material of the time, but also a fuel shortage.</p>
<p>What should it become? And more importantly, why?</p>
<p>(depends on both the length of the period of daylight as well as on) should be (depends on both the length of the period of daylight AND)…BOTH…AND is the correct correlative conjunction. </p>
<p>In the sixteenth century, (the forests were destroyed in Britain, which meant not only a shortage) of the most important building material of the time, but also a fuel shortage.</p>
<p>I don’t see anything wrong here.</p>
<p>
</p>
<p><a href=“depends%20on%20both%20the%20length%20of%20the%20period%20of%20daylight%20as%20well%20as%20on”>quote</a> should be (depends on both the length of the period of daylight AND)…BOTH…AND is the correct correlative conjunction.
[/quote]
</p>
<p>Additionally, you have to drop the second “on.”</p>