ensue为不及物动词，不可能后接从句或引导从句。

Immediately ensue puffing off of chimney smoke in the air，laughter and neigh， and wailing of horns from passing vehicles.

这是一个完全倒装句，主语后移到句末以突出强调主语。如果不倒装，句子是这样的：

Puffing off of chimney smoke in the air，laughter and neigh， and wailing of horns from passing vehicles ensue immediately.

四个并列的主语+不及物动词ensue+状语。

其中Puffing off of chimney smoke in the air 和 wailing of horns from passing vehicles ensue immediately 都是名词化的动名词，of介词短语为名词化的动名词的逻辑主语。

谓语动词ensue用一般现在时是为了描写生动，使读者产生亲临其境的感觉。这种现在时的用法称为“历史性现在”。