John Davis wrote: > Dear Dialling Colleagues, > > The British Sundial Society (BSS) has decided that a Glossary of dialling > terms would be a good idea. <snip> In the meantime, it can be viewed on my > rudimentary web site > at: > > www.btinternet.com/~john.davis > > I'd welcome any feedback, and am quite willing to be over-ruled on choices > of symbols etc, if there is a general consensus. > > John > ---------------------------------------------- > Dr J R Davis > Flowton, UK > 52.08N, 1.043E > email: [EMAIL PROTECTED]
Well done John, an excellent job. I have a few specific points, none, I think, covered by Fer: Declination: You are showing your age! For some time now, the maximum has been closer to 23.4 than 23.5 degrees. Dial types/analemmatic: Simpler to say "The gnomon position lies on the N-S minor axis, at a point...". Misspelling "gnomom" for "gnomon". I don't agree that it is for artistic purposes only - it is to allow you to calculate mean time. Analemmatic dials were originally most commonly used in a portable pair of sundials (one analemmatic, the other a conventional horizontal sundial) which is self-orienting. I would add a note that one should not confuse "analemmatic" with "analemma", or a reference to Fred Sawyer's article on the subject. Dial types/armillary sphere: Misspelling "equinoctal" Dial types/auxiliary: Misspelling "equinoctal". Also, isn't it "auxilliary" in the UK? Dial types/bifilar: I would say "...their heights above the plane being a function of the latitude of the dial.". You use the term "equi-angular" which isn't defined in the glossary, though "equiangular" is listed as a dial type. Personally, I think I would move "equiangular" out of dial types, into the glossary. Dial types/Butterfield: "consist" for "consists". I would prefer to say that the gnomon has adjustable angle, not height. Dial types/Capuchin: "Regiomontanus" needs a capital R here and under "Little Ship". Dial types/complementary: I find the description most unclear, even though I think I know what it is trying to say. Also, I think it is misleading in equating style height and wrong in its reference to the co-latitude. May I suggest "a horizontal sundial used as an aid to designing a vertical or reclining sundial. Its gnomon and hour lines are calculated not for the site of the proposed vertical dial but for the location where the earth's surface is parallel to the dial plate of the proposed dial. For a simple direct south vertical dial, for instance, the complementary dial would be identical to a horizontal dial for the point 90 degrees to the south. Dial types/cross: I don't find "..the top pointing south and parallel to the polar plane" clear, and the hyperlink is to "polar dial" which isn't helpful. I propose "..the top pointing south." Dial types/cube: I don't find the reference to co-latitude clear. I propose "..set the cube so that its 'top' surface is parallel to the equator." I would cross-reference "polyhedron" from here. Dial types/double horizontal: I am not familiar with this, but suspect that the projection of the sky might be "stereographic", not "stereoscopic". Dial types/equatorial: Why do you say this is a misnomer? I think it is a perfectly acceptable alternative term, indeed I prefer it to "equinoctial". Cousins uses it. Dial types/equiangular: Since equinoctial dials are equiangular, it is incorrect to say that the mounting of the gnomon must be movable. Dial types/equinoctial: As this glossary will be read by people living outside the UK, I would replace "BST" by "Summer Time / Daylight Saving Time". You describe only dials with a flat dial plate, but many equinoctial dials use instead the inside of a ring or section of cylinder. In these, there is no "underside", of course. Any equinoctial which is adjustable for latitude is universal. I would mention this here, as well as saying "See also 'universal equinoctial ring ~'". Dial types/Foster Lambert: You mention only one case - the diametral dial. But (as Fer points out, also,) Foster Lambert includes many other projections, such as the RGO sundial you mention under equiangular, and two horizontal equiangular forms. See http://www.iaehv.nl/users/ferdv/projdial.htm Dial types/globe: For "It can also indicate the meridian.." I would say "It indicates..". I think you are wrong to distinguish between the alignments of a globe dial and that of a terrella. Surely they are identical? Dial types/heliochronometer: I doubt if we will all agree about what makes a heliochronometer, but I certainly don't agree that it implies a "mechanism", and indeed your last example has no mechanism. Nor is it universally agreed that it must show mean time, I think. Dial types/hemispherium and hemicyclium: I don't think it is accurate to say it is "essentially a horizontal altitude dial", as that implies that the only marks are horizontal rings. The Roman example in Cousins' book seems to have correct hour lines and declination lines, so is really an equinoctial dial. Is there any real difference between these and a scaphe? Dial types/Little Ship: Misspelling "Venecian" for "Venetian". Dial types/magnetic: There is also a type, illustrated in Basserman-Jordan, where the compass needle indicates the time. Dial type/moon: Misspelling "Queen's" for "Queens'" (There were two queens.). Dial types/polar: I find the description a little difficult to interpret. I propose "in which the dial plate is south-facing, but reclines so that it is parallel to the polar axis." Dial types/polarised light: You say it is not particularly accurate, but I am sure I have read that it is very accurate. I cannot see how it could be, so you may well be right. Dial types/solar chronometer: I imagine this was a term invented by Wheatstone. I haven't heard it applied to other dials with clock faces. Dial types/universal equinoctial ring: As an alternative to an aperture, a nodus is sometimes seen, I think. Ecliptic: Eclipses occur in the ecliptic because the sun is, be definition, always in it, not because the moon's orbit is near the ecliptic. Ellipse: I don't know why you say "(approx.)". Surely any deviation is so small as to be completely negligible. Equinoxes: Should say "...the zero of celestial longitude and right ascension". Jaipur: The sundial with a 90 foot gnomon is equinoctial, not horizontal, isn't it? (I could well be wrong.) Leap-year: I don't like "The introduction of leap years causes the EoT on a particular day of the year to exhibit a small periodic variation." I propose "Despite the introduction of leap years the EoT on a particular day of the year exhibits a small periodic variation, because a year is not a whole number of days." I would add an entry for "Self-orienting" or, if you prefer, "Self-orientating": a portable sundial which, when adjusted for latitude and/or date, can be used to find the direction of South. I think the term "self-southing" is also used. Solar compass: Surely, these are versions of an azimuth dial, not an altitude dial, aren't they? Please note that some of my comments are to be interpreted as questions, not definite claims that the glossary is wrong. Regards Chris Lusby Taylor Newbury, England 51.5N, 0.5W Content-Type: text/x-vcard; charset=us-ascii; name="clusby.vcf" Content-Description: Card for Chris Lusby Taylor Content-Disposition: attachment; filename="clusby.vcf" Content-Transfer-Encoding: 7bit Attachment converted: Macintosh HD:clusby.vcf (TEXT/ttxt) (0000A080)
