The mirrors are placed in concentric semicircles facing a tower , on top of which the boiler and the turbine sit .

这些镜子放在面向塔的同心半圆上，塔上就是锅炉和涡轮。

It is only recently that researchers have started looking at the strange squiggles , semicircles , lines and zigzags that surround them .

只有到了现在，研究人员才刚刚开始观察石壁上那些奇怪的胡乱书写的文字、半圆图形、线条和锯齿形。