Harper lee satirises the white community by making them look bad by making mr. Ewell be angry at Atticus even though he knows he was wrong. On the other hand she contrasts miss stephanie and miss maudie with one giving atticus cake to show nothing has changed and the other willing to spread rumours and in contrast to the black community who rewarded him heavily with food.
Tom Robinson can be compared to a mocking bird.
A mocking bird : Sings for humans and does no harm. Gets shot by humans for fun without doing nothing bad. Is lower then humans.
Tom Robinson : Helped mayela ewell with hard work. Got sent to court without doing the crime. Is in a part of community considered lower.
” I shivered, though the night was hot. The feeling grew in the court room was exactly the same as cold February morning, when the mocking birds were still, and the carpenters had stopped hammering. ”
Semantics is all about the field in which a text can be interpreted. Some people after reading this would diagnose scout with Diaphoresis a case where a person is feeling cold in a warm room but is still sweating without the need for heat or work. “Diaphoresis can come from pain, lack of oxygen or sugar in the bloodstream, or from fear”. In this case it could be diaphoresis also known as cold sweat because there is an element of fear which can trigger the reactions as scout is scared about what will happen to Tom Robinson during the case.
However I believe that Harper Lee used a semantic to explain the cold athmosphere that was happening in the court room. When she Speaks about the mocking birds that were still and the hammering that stopped she could have related to create tention as if the whole world has focused on the court case like it all depended on it making it important enough to put emotional strain on everyone.
sources: Diaphoresis http://firstaid.about.com/od/glossary/g/09_Diaphoresis.htm