Construction on the solar greenhouse continues between other projects. We are in the middle of installing the 20 tons of rock into the base of what will be the growing beds. The perforated pipe is for delivering warm air that is distributed to the rock bed from the peak of the greenhouse where the air temperatures are the warmest. The idea is to warm up the large mass of rock during the day and have it help maintain growing temperatures during the night, a very useful arrangement in our climate.