You couldn't use pure water in the sun to float a mirror because algae would soon grow in the water. I don't know what kind of clear liquid is used in my Silva compass that uses this liquid to dampen the needle. Perhaps there's a little alcohol added to keep it sterile.
John John L. Carmichael Jr. Sundial Sculptures 925 E. Foothills Dr. Tucson Arizona 85718 USA Tel: 520-696-1709 Email: [EMAIL PROTECTED] Website: <http://www.sundialsculptures.com> ----- Original Message ----- From: "Steve Lelievre" <[EMAIL PROTECTED]> To: "Sundial Mail List" <[email protected]> Sent: Sunday, January 06, 2002 8:04 AM Subject: Re: Ceiling Sundials: Mirror Placement > John Carmichael suggested floating the mirror in mercury to level it, and > then Dave Bell pointed out that the clean surface of the mercury could be > the mirror. > > Since mercury is a bit of a problem to work with, could a dish of water > serve instead? In John's case, he just needs the mirror to be able to float > on the liquid. I just tested a CD and it floated on water. The plastic is > more dense than water but if the CD is dropped gently into place, it floats > due to surface effects. A small piece could be cut from a spare CD to make a > mirror of the required size, or the hole at the centre of the annular > reflection of an intact CD could act as the spot. A CD is not as reflective > as a mirror of course, but I think it would be good enough. I can't test > this - it's cloudy here today. The dish would need to be only slightly wider > than the mirror to prevent it floating off centre. Also, the dish might need > to be full to the brim so that the sunray does not need to travel through > its the walls. Alternatively, could the reflection from water itself be > enough, like Dave's way with mercury? > > A vessel such as a wineglass on the window sill would look quite welcoming > from outside. Of course, the choice of liquid would be important, and > contrary to the sundialling norm, Moonshine might work better than a Tequila > Sunrise. > > Steve > > > > >
