There has been some confusion in the discussion so far. Here is my take: The sundial pictured is called a “vertical disk dial.” It is an altitude sundial. The example pictured is similar to one at CHSI (inv. 7270) signed “I W” with a punch mark of a crown and date 1672. It is for latitude 52° 35'.
Most of the vertical disk dials are for single latitudes, and have a single suspension point. However, a few try to be adjustable for latitude. At Harvard, an example is inv. 7264, which is signed and dated “ P. L. K. / 1755.” I will tweet images of them and post them in this Dropbox: https://www.dropbox.com/sh/9qg1p0kejm3o842/AACoYez5bVtRU5JhPJuJgOK8a Sara Sara J. Schechner Altazimuth Arts 42°36'N 71° 22'W West Newton, MA 02465 http://www.altazimutharts.com/ Sara J. Schechner, Ph.D. David P. Wheatland Curator of the Collection of Historical Scientific Instruments Department of the History of Science, Harvard University Science Center 251c, 1 Oxford Street, Cambridge, MA 02138 Tel: 617-496-9542 | Fax: 617-496-5932 | sche...@fas.harvard.edu http://scholar.harvard.edu/saraschechner http://chsi.harvard.edu/ On Sun, Jun 1, 2014 at 6:13 PM, Steve Lelievre <steve.lelievre.can...@gmail.com<mailto:steve.lelievre.can...@gmail.com>> wrote: Hi folks, http://www.pinterest.com/pin/301178293801331061/<https://urldefense.proofpoint.com/v1/url?u=http://www.pinterest.com/pin/301178293801331061/&k=AjZjj3dyY74kKL92lieHqQ%3D%3D%0A&r=Y3uaNkd%2BN%2BBEMo7BAxbEQqOqpMk6uxYnCJsB4uxugzo%3D%0A&m=izSTWMgNnFv8DfKU%2Bd249F%2B%2FyJSDHvIkXOyVUqkC8%2FU%3D%0A&s=7631973f481f1363e8d75a48591133eaed99295b1faf9d05a8f4a1ea4c25175d> What type of dial is this; I realize it's a form of altitude dial, but is there a specific name for it? The accompanying note states that the dial can be adjusted for latitude by moving "the attachment point". I don't understand which part of the mechanism does that. Can anyone explain it for me? Lastly, I'm appreciate references for articles or webpages that discuss these dials - history and mathematics. Thanks, Steve --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial<https://urldefense.proofpoint.com/v1/url?u=https://lists.uni-koeln.de/mailman/listinfo/sundial&k=AjZjj3dyY74kKL92lieHqQ%3D%3D%0A&r=Y3uaNkd%2BN%2BBEMo7BAxbEQqOqpMk6uxYnCJsB4uxugzo%3D%0A&m=izSTWMgNnFv8DfKU%2Bd249F%2B%2FyJSDHvIkXOyVUqkC8%2FU%3D%0A&s=dcc654938564a18e96ec2bb9f94d253a409277009b33d3b5467c6486ffb43f43>
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