THE electronic mailing list proposed in Issue no. 3 of Sphæra is now active and has some 280 subscribers. Hosted by the Museum, it provides a space for questions, discussion and announcements concerning the history of scientific instruments. It does not carry advertisements or other commercial material. Anyone with an E-mail account can join by sending the message ‘subscribe rete’ to the address email@example.com. ‘Subscribe’ is, of course, merely a term of art: there is no charge for joining the list.