Finally got the spring cleaned out enough to see the spring box. The right hand board is made out of oak while the other two are made out of poplar. The aze marks are still visible on the bottom board. Suprizingly it is still white colored after all these years. When poplar is exposed to air, it will typically turn brown in less than 5 years. I measured the temperature and it read 64 degrees. Not refrigerator cold but refreshing on an 85 degree day. There is evidently a board missing on the end. It won't hold the water as deep as it needs to. I am going to add a couple of boards and see how it works.