We have two external book drops available to library patrons. The “Bostock” book drop is an aluminum box that sits under an archway between our two library buildings. It is somewhat protected from the elements by being under a stone archway and nestled against the library building. The “Drive By” book drop is a powder-coated steel box located at the back of the library near the parking lot. It sits in a sunny spot and is exposed to the elements. Last fall, a coworker in Circulation came to me with his concerns about the conditions of the books he retrieved from the external book drops. He said they often felt damp and even warm. I thought it would be interesting to put a HOBO datalogger in each of our external book drops to see what was happening inside.

Last August we put one HOBO in the Drive By book drop for a short test. I knew it was likely to be hot and humid in that box. I was eager to see the actual data. My advice? If you aren’t prepared for the truth, do not seek it. At its hottest, the Drive By box  reached 131 degrees Fahrenheit. At its most humid it reached 99% rH.

That test brought up a lot of questions. Since we were moving into the cooler and drier fall and winter seasons, we decided to do a longer test during the spring semester. This January, we put a HOBO in each of the external book drops and set them to record at the same time and interval rate so we could compare them to each other.

This afternoon I downloaded the data for the past week. This week was a typical North Carolina winter week. We had low temps in the 30F’s and high temps close to 60F. There were rainy days and sunny days.

You can see that even in winter that steel box gets quite warm on sunny days. The humidity levels range from very wet to very arid. The aluminum box has its extremes, but they don’t spike as high as the steel box. It’s interesting to think about how the different metals, and the different locations, may be effecting the interior conditions.

I do not expect external book drops to have perfect preservation environments. I am, however, concerned about the extremes these environments present. I’m sharing this data with the Head of Access and Delivery Services so we can figure out what, if anything, we should recommend to the library in terms of these boxes.

I really love these HOBOs. They are easy to use and reasonably priced, and the data  can be easily downloaded in a variety of ways. Henry wrote a review of these HOBOs recently if you are interested in learning more about them.