Maria I am puzzled as to why you don't want reports of practical experiences. These are what determine the value of such devices. We use our visitor's books to do the following. 1. Give visitors a chance to provide feedback. This is for THEIR benefit. 2. Identify our strong points/weaknesses in their eyes. This is for OUR benefit. 3. Have something to show our sponsors and my board- 99% of comments are very positive and the wide geographical origins of those who fill in the books is impressive. We realise that only a narrow subset of people fill in the books. We use other methods to produce statistical information. Glen Moore Director, Science Centre and Planetarium Wollongong, Australia [log in to unmask] fax: 61 42 836665 web: http://www.uow.edu.au/science_centre/home.html