For the Macbook Air, you cannot daisy chain monitors through the Thunderbolt/MiniDisplay Port Connect. You can however use a USB 3.0 to HDMI converter (you will need to install the associated driver) like this one: SIIG USB 3.0 to HDMI/DVI Multi Monitor Video Adapter. Once you install the driver and restart the computer, the Macbook will detect the second monitor and you can configure the monitor layout.
I had bought a pair of Dell U2417H monitors and was surprised when they would not work in a daisy chain configuration. I am also very happy that this solution worked as it has turned my wife’s Air into a much more powerful workstation.
