What is one early example of air conditioning?

One early example of air conditioning is the practice of hanging wet towels across an open window. This method takes advantage of the principles of evaporative cooling, where the water from the wet towels evaporates and absorbs heat from the surrounding air. As the air passes through the damp towels, it is cooled before entering the living space, thus lowering the indoor temperature somewhat.

This approach does not rely on advanced technology or machinery, making it a simple solution to heat relief that people have used for centuries. It effectively demonstrates early human ingenuity in addressing comfort in hot weather, showing how basic materials and natural processes can be leveraged for cooling purposes.

The other options, while they may also relate to cooling methods, do not specifically represent air conditioning in the historical context. For instance, using ice blocks can create cooling effects, but it lacks the efficiency and intent of modern air conditioning systems. Installing ceiling fans circulates air but does not lower the temperature. Creating a cool basement can help avoid heat but isn't an active method of cooling the air in the same way that evaporative cooling does.